Magnetic recording device

Abstract

To provide a magnetic recorder capable of improving the recording density.SOLUTION: According to an embodiment, a magnetic recorder includes a magnetic head and a control unit. The magnetic head includes: a first magnetic pole; a second magnetic pole; a magnetic element which is provided between the first magnetic pole and the second magnetic pole; and a coil. The control unit is electrically connected to the magnetic element and the coil. The control unit enables recording operation. The control unit supplies a recording current to the coil while applying an element voltage to the magnetic element in the recording operation. An alternating magnetic field is generated from the magnetic element to which the element voltage has been applied. Differential resistance of electric resistance of the magnetic element when the voltage applied to the magnetic element while the recording current is supplied to the coil is changed turns into a first differential resistance peak when the applied voltage is a first voltage. The differential resistance turns into a second differential resistance peak when the applied voltage is a second voltage. The second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Embodiments of the present invention relate to a magnetic recording device.

Background Art

[0002] Information is recorded on a magnetic recording medium such as a HDD (Hard Disk Drive) using a magnetic head. In a magnetic recording device, an improvement in recording density is desired.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Embodiments of the present invention provide a magnetic recording device capable of improving recording density.

Means for Solving the Problems

[0005] According to an embodiment, a magnetic recording device includes a magnetic head and a control unit. The magnetic head includes a first magnetic pole, a second magnetic pole, a magnetic element provided between the first magnetic pole and the second magnetic pole, a first terminal electrically connected to one end of the magnetic element, a second terminal electrically connected to the other end of the magnetic element, and a coil. The control unit is electrically connected to the magnetic element and the coil. The control unit is capable of a recording operation. In the recording operation, the control unit supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. . beforeWhen the recording current is supplied to the recording coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage. The differential resistance reaches a second differential resistance peak when the applied voltage is a second voltage. The second voltage is higher than the first voltage. The element voltage is higher than the first voltage and lower than the second voltage. [Brief explanation of the drawing]

[0006] [Figure 1] Figure 1 is a schematic cross-sectional view illustrating a magnetic recording device according to the first embodiment. [Figure 2] Figure 2 is a schematic diagram illustrating the characteristics of a magnetic recording device according to the first embodiment. [Figure 3] Figures 3(a) and 3(b) are schematic diagrams illustrating the characteristics of a magnetic recording device according to the first embodiment. [Figure 4] Figure 4 is a schematic cross-sectional view illustrating a part of a magnetic recording device according to the first embodiment. [Figure 5] Figure 5 is a schematic plan view illustrating a part of the magnetic recording device according to the first embodiment. [Figure 6] Figures 6(a) to 6(d) are schematic diagrams illustrating the operation of the magnetic recording device according to the first embodiment. [Figure 7] Figures 7(a) and 7(b) are schematic diagrams illustrating the simulation results for a magnetic recording device according to the first embodiment. [Figure 8] Figures 8(a) to 8(c) are schematic diagrams illustrating the simulation results for a magnetic recording device according to the first embodiment. [Figure 9] Figures 9(a) and 9(b) are schematic diagrams illustrating the simulation results for a magnetic recording device according to the first embodiment. [Figure 10] Figures 10(a) and 10(b) are schematic diagrams illustrating the simulation results for a magnetic recording device. [Figure 11]Figure 11 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. [Figure 12] Figure 12 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. [Figure 13] Figure 13 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. [Figure 14] Figure 14 is a schematic perspective view illustrating a magnetic recording device according to the second embodiment. [Figure 15] Figure 15 is a schematic perspective view illustrating a part of a magnetic recording apparatus according to an embodiment. [Figure 16] Figure 16 is a schematic perspective view illustrating a magnetic recording device according to an embodiment. [Figure 17] Figures 17(a) and 17(b) are schematic perspective views illustrating a part of a magnetic recording apparatus according to an embodiment. [Modes for carrying out the invention]

[0007] (First Embodiment) Figure 1 is a schematic cross-sectional view illustrating a magnetic recording device according to the first embodiment. As shown in Figure 1, the magnetic recording device 210 according to this embodiment includes a magnetic head 110 and a control unit 75. The magnetic recording device 210 may also include a magnetic recording medium 80. At least a recording operation is performed in the magnetic recording device 210. In the recording operation, information is recorded on the magnetic recording medium 80 using the magnetic head 110.

[0008] The magnetic head 110 includes a recording unit 60. As will be described later, the magnetic head 110 may also include a playback unit. The recording unit 60 includes a first magnetic pole 31, a second magnetic pole 32, a magnetic element 20, and a coil 30c. The magnetic element 20 is provided between the first magnetic pole 31 and the second magnetic pole 32.

[0009] For example, the first magnetic pole 31 and the second magnetic pole 32 form a magnetic circuit. The first magnetic pole 31 is, for example, a main magnetic pole. The second magnetic pole 32 is, for example, a trailing shield. It is also possible that the first magnetic pole 31 is a trailing shield and the second magnetic pole 32 is a main magnetic pole.

[0010] The direction from the magnetic recording medium 80 to the magnetic head 110 is defined as the Z-axis direction. One direction perpendicular to the Z-axis direction is defined as the X-axis direction. The direction perpendicular to the Z-axis direction and the X-axis direction is defined as the Y-axis direction. The Z-axis direction corresponds to, for example, the height direction. The X-axis direction corresponds to, for example, the down-track direction. The Y-axis direction corresponds to, for example, the cross-track direction. Along the down-track direction, the magnetic recording medium 80 and the magnetic head 110 move relative to each other. A recording magnetic field generated from the magnetic head 110 is applied to a desired position on the magnetic recording medium 80. The magnetization at the desired position on the magnetic recording medium 80 is controlled in a direction corresponding to the recording magnetic field. Thereby, information is recorded on the magnetic recording medium 80.

[0011] The direction from the first magnetic pole 31 to the second magnetic pole 32 is defined as the first direction D1. The first direction D1 substantially follows the X-axis direction. In an embodiment, the first direction D1 may be inclined with respect to the X-axis direction. The angle of inclination is, for example, greater than 0 degrees and less than or equal to 10 degrees.

[0012] In this example, a part of the coil 30c is between the first magnetic pole 31 and the second magnetic pole 32. In this example, a shield 33 is provided. In the X-axis direction, the first magnetic pole 31 is between the shield 33 and the second magnetic pole 32. Another part of the coil 30c is between the shield 33 and the first magnetic pole 31. An insulating portion 30i is provided between these plurality of elements. The shield 33 is, for example, a leading shield. The magnetic head 110 may include a side shield (not shown).

[0013] As shown in FIG. 1, a recording current Iw is supplied from a recording circuit 30D to a coil 30c. For example, a first coil terminal Tc1 and a second coil terminal Tc2 are provided on the coil 30c. Through these coil terminals, the recording current Iw is supplied to the coil 30c. From a first magnetic pole 31, a recording magnetic field corresponding to the recording current Iw is applied to a magnetic recording medium 80.

[0014] As shown in FIG. 1, the first magnetic pole 31 includes a medium facing surface 30F. The medium facing surface 30F is, for example, an ABS (Air Bearing Surface). The medium facing surface 30F faces, for example, the magnetic recording medium 80. The medium facing surface 30F is along, for example, the X-Y plane.

[0015] As shown in FIG. 1, an element circuit 20D is electrically connected to a magnetic element 20. In this example, the magnetic element 20 is electrically connected to a first magnetic pole 31 and a second magnetic pole 32. A first terminal T1 and a second terminal T2 are provided on a magnetic head 110. The first terminal T1 is electrically connected to one end of the magnetic element 20 through a first wiring W1 and the first magnetic pole 31. The second terminal T2 is electrically connected to the other end of the magnetic element 20 through a second wiring W2 and the second magnetic pole 32. From the element circuit 20D, for example, an element current ic is supplied to the magnetic element 20.

[0016] As shown in FIG. 1, the element current ic has a direction from the first magnetic pole 31 to the second magnetic pole 32. As shown in FIG. 1, an electron flow je accompanying the element current ic has a direction from the second magnetic pole 32 to the first magnetic pole 31.

[0017] For example, when an element current ic equal to or greater than a threshold value flows through the magnetic element 20, oscillation occurs in a magnetic layer included in the magnetic element 20. The magnetic element 20 functions as, for example, a STO (Spin-Torque Oscillator). Along with the oscillation, an alternating magnetic field (for example, a high-frequency magnetic field) is generated from the magnetic element 20. The alternating magnetic field generated by the magnetic element 20 is applied to the magnetic recording medium 80, assisting the recording on the magnetic recording medium 80. For example, MAMR (Microwave Assisted Magnetic Recording) can be implemented.

[0018] The recording circuit 30D and the element circuit 20D are included in the control unit 75. The control unit 75 is electrically connected to the magnetic element 20 and the coil 30c. The control unit 75 can supply a recording current Iw to the coil 30c and an element current ic to the magnetic element 20.

[0019] For example, the control unit 75 (element circuit 20D) applies an element voltage V20 corresponding to the element current ic between the first terminal T1 and the second terminal T2. In practice, the element current ic may be controlled by controlling the element voltage V20. The element voltage V20 corresponds, for example, to the potential of the first terminal T1 with respect to the potential of the second terminal T2. The wiring resistance between these terminals and the magnetic element 20 is substantially constant. The voltage difference between the element voltage V20 and the voltage drop in the wiring is applied to the magnetic element 20. A change in the voltage applied to the magnetic element 20 corresponds to a change in the element voltage V20. For example, when considering the characteristics of the magnetic element 20 based on the applied voltage, the voltage applied between the first terminal T1 and the second terminal T2 (element voltage V20) may be considered to be substantially applied to the magnetic element 20. For example, the rate of change in the element voltage V20 is substantially the same as the rate of change in the voltage applied to the magnetic element 20.

[0020] As described above, during the recording operation, the control unit 75 applies an element voltage V20 between the first terminal T1 and the second terminal T2 while supplying a recording current Iw to the coil 30c. As described above, an alternating magnetic field is generated from the magnetic element 20 to which a voltage corresponding to the element voltage V20 is applied. An alternating magnetic field is generated from the magnetic element 20 during the recording operation. An example of the element voltage V20 (and element current ic) in the embodiment will be described later.

[0021] The following describes examples of the characteristics of the magnetic head 110 according to the embodiment. Figure 2 is a schematic diagram illustrating the characteristics of a magnetic recording device according to the first embodiment. The horizontal axis in Figure 2 represents the applied voltage Va1 applied by the control unit 75 (element circuit 20D) between the first terminal T1 and the second terminal T2. The applied voltage Va1 corresponds to the voltage applied to the magnetic element 20. The horizontal axis in Figure 2 corresponds to the supply current ia1 supplied to the magnetic element 20. The supply current ia1 corresponds to the current flowing between the first terminal T1 and the second terminal T2. The vertical axis in Figure 2 represents the electrical resistance Re1 of the magnetic element 20. The product of the electrical resistance Re1 and the supply current ia1 corresponds to the applied voltage Va1. As will be described later, the magnetic element 20 oscillates at a specific applied voltage Va1 (and a specific supply current ia1). An alternating magnetic field is generated from the magnetic element 20. The electrical resistance of the magnetic element 20 changes (oscillates) in response to this oscillation. In Figure 2, the change in electrical resistance Re1 associated with the oscillation is shown as an average. The electrical resistance Re1 in Figure 2 is the time-averaged electrical resistance of the magnetic element 20. In Figure 2, the electrical resistance Re1 is the time-averaged measurement result. The electrical resistance Re1 in Figure 2 is the DC resistance.

[0022] Figure 2 illustrates the change in the electrical resistance Re1 of the magnetic element 20 when the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is changed while a recording current Iw is supplied to the coil 30c. When the applied voltage Va1 is positive, the change in the applied voltage Va1 can be, for example, an increase from 0 volts.

[0023] As shown in Figure 2, the electrical resistance Re1 increases in proportion to the increase in the absolute value of the applied voltage Va1. Below, we will describe the region where the applied voltage Va1 is positive. In the region where the applied voltage Va1 is positive, the direction of the element current ic flowing through the magnetic element 20 is from the first magnetic pole 31 to the second magnetic pole 32. When the applied voltage Va1 is positive, for example, the potential of the first magnetic pole 31 is higher than the potential of the second magnetic pole 32.

[0024] For example, in the region where the absolute value of the applied voltage Va1 is small, the electrical resistance Re1 decreases or increases sharply. This phenomenon is thought to be related to the voltage generated by the thermoelectric effect in the magnetic element 20, for example. This sharp decrease or increase can be eliminated by correcting the applied voltage Va1 when deriving the electrical resistance Re1. A voltage is obtained from the applied voltage Va1 with the voltage generated by the thermoelectric effect removed. The ratio of this voltage (with the voltage generated by the thermoelectric effect removed) to the supply current ia1 is obtained. From the obtained ratio, the electrical resistance Re1 with the sharp decrease or increase removed is obtained. The value of the voltage generated by the thermoelectric effect is estimated so as to appropriately eliminate the sharp decrease or increase in the electrical resistance Re1. In the measurement of differential resistance described later, this sharp decrease or increase does not occur substantially.

[0025] For example, as the positive applied voltage Va1 increases, the electrical resistance Re1 increases in effect as a function of the square of the applied voltage Va1. This is thought to be related to the temperature rise caused by Joule heating due to the current flowing through the magnetic element 20.

[0026] Furthermore, as shown in Figure 2, when the applied voltage Va1 is the first voltage V1, the electrical resistance Re1 changes discontinuously in a step-like manner. In this example, when the applied voltage Va1 is the second voltage V2, the electrical resistance Re1 changes discontinuously in a step-like manner. The second voltage V2 is higher than the first voltage V1.

[0027] When a recording current Iw is supplied to the coil 30c, for example, a DC applied voltage Va1 (and a DC supply current ia1) is supplied to the magnetic element 20. At this time, a high-frequency signal (e.g., an alternating signal) generated from the magnetic element 20 can be extracted. The alternating frequency signal can be extracted from the first terminal T1 or the second terminal T2. The high-frequency signal can be extracted, for example, as the product of an alternating current and an alternating voltage. The high-frequency signal is, for example, an alternating power. For example, by extracting the high-frequency signal near the first terminal T1 or the second terminal T2, a high-frequency signal can be obtained with low attenuation. The extracted high-frequency signal is thought to be associated with the oscillation of the electrical resistance Re1 of the magnetic element 20.

[0028] When a high-frequency signal is generated, an alternating magnetic field is also generated. The frequency of the high-frequency signal corresponds to the frequency of the alternating magnetic field generated from the magnetic layer in the magnetic element 20. The intensity of the high-frequency signal corresponds to the intensity of the alternating magnetic field generated from the magnetic layer in the magnetic element 20. If the magnetic layer is not oscillating, a high-frequency signal cannot be substantially obtained.

[0029] The region where the applied voltage Va1 is 0 volts or more and less than the first voltage V1 corresponds to the first state ST1. In the first state ST1, substantially no high-frequency signal is obtained from the magnetic element 20. For example, in the first state ST1, the electrical resistance Re1 does not change in an oscillating manner.

[0030] The region where the applied voltage Va1 is higher than the first voltage V1 and less than the second voltage V2 corresponds to the second state ST2. In the second state ST2, a high-frequency signal is obtained from the magnetic element 20. For example, in the second state ST2, the electrical resistance Re1 changes in an oscillating manner. In the second state ST2, an alternating magnetic field (high-frequency magnetic field) is generated from the magnetic element 20.

[0031] The region where the applied voltage Va1 is higher than the second voltage V2 corresponds to the third state ST3. In the third state ST3, a high-frequency signal is obtained from the magnetic element 20. For example, in the third state ST3, the electrical resistance Re1 changes in an oscillating manner. As will be described later, the oscillation state in the third state ST3 is different from the oscillation state in the second state ST2. In the third state ST3, an alternating magnetic field (high-frequency magnetic field) of a different state is generated from the magnetic element 20.

[0032] At the first voltage V1, a transition occurs between the first state ST1 and the second state ST2. At the second voltage V2, a transition occurs between the second state ST2 and the third state ST3.

[0033] The region where the supply current ia1 is greater than or equal to 0 and less than the first current i1 corresponds to the first state ST1. In the first state ST1, virtually no high-frequency signal is obtained from the magnetic element 20. For example, in the first state ST1, the electrical resistance Re1 does not change in an oscillating manner.

[0034] The region where the supply current ia1 is higher than the first current i1 and less than the second current i2 corresponds to the second state ST2. In the second state ST2, a high-frequency signal is obtained from the magnetic element 20. For example, in the second state ST2, the electrical resistance Re1 changes in an oscillating manner. In the second state ST2, an alternating magnetic field (high-frequency magnetic field) is generated from the magnetic element 20.

[0035] The region where the supply current ia1 is higher than the second current i2 corresponds to the third state ST3. In the third state ST3, a high-frequency signal is obtained from the magnetic element 20. In the third state ST3, the electrical resistance Re1 changes in an oscillating manner. In the third state ST3, an alternating magnetic field (high-frequency magnetic field) of a different state is generated from the magnetic element 20.

[0036] In the first current i1, a transition occurs between the first state ST1 and the second state ST2. In the second current i2, a transition occurs between the second state ST2 and the third state ST3.

[0037] Figures 3(a) and 3(b) are schematic diagrams illustrating the characteristics of a magnetic recording device according to the first embodiment. The horizontal axis in Figure 3(a) represents the applied voltage Va1. The horizontal axis in Figure 3(b) represents the supplied current ia1. The vertical axis in both Figures 3(a) and 3(b) represents the differential resistance Rd1 of the magnetic element 20. The differential resistance Rd1 is the ratio of a small change d(Va1) in the applied voltage Va1 to a small change d(ia1) in the supplied current ia1. For example, the differential resistance Rd1 is d(Va1) / d(ia1). The characteristics in these figures are those when a recording current Iw is supplied to the coil 30c. For example, the differential resistance Rd1 corresponds to the differential resistance of the magnetic element 20 when the applied voltage Va1 is changed while a recording current Iw is supplied to the coil 30c. The recording current Iw is the current that flows through the coil 30c during the recording operation. The direction (polarity) of the recording current Iw changes depending on the information to be recorded. In the following example, the direction (polarity) of the recording current Iw is such that a magnetic field is generated that includes a component in the direction from the second magnetic pole 32 to the first magnetic pole 31.

[0038] As shown in Figure 3(a), the differential resistance Rd1 of the magnetic element 20 reaches its first differential resistance peak p1 when the applied voltage Va1 is the first voltage V1. The differential resistance Rd1 reaches its second differential resistance peak p2 when the applied voltage Va1 is the second voltage V2. The second voltage V2 is higher than the first voltage V1. In this embodiment, the element voltage V20 applied during the recording operation is higher than the first voltage V1 and lower than the second voltage V2.

[0039] Such an element voltage V20 provides an appropriate alternating magnetic field, enabling proper MAMR (Magnetic Magnetic Recording). According to this embodiment, a magnetic recording device capable of improving recording density can be provided.

[0040] As shown in Figure 3(b), the differential resistance Rd1 of the magnetic element 20 reaches a first differential resistance peak p1 when the supply current ia1 supplied to the magnetic element 20 is the first current i1. The differential resistance Rd1 reaches a second differential resistance peak p2 when the supply current ia1 is the second current i2. The second current i2 is greater than the first current i1. In this embodiment, during recording operation, the element current ic is greater than the first current i1 and less than the second current i2.

[0041] Such an element current IC can provide an appropriate alternating magnetic field. MAMR can be properly implemented. According to this embodiment, a magnetic recording device capable of improving recording density can be provided.

[0042] As already explained, the second state ST2 corresponds to the case where the applied voltage Va1 is higher than the first voltage V1 and lower than the second voltage V2. In the second state ST2, an alternating magnetic field is generated from the magnetic element 20. The first state ST1 corresponds to the case where the applied voltage Va1 is lower than the first voltage V1. In the first state ST1, the alternating magnetic field described above is not generated from the magnetic element 20. The first voltage V1 corresponds to the threshold value for oscillation.

[0043] In the embodiment, the frequency of the alternating magnetic field is, for example, 10 GHz or more and 40 GHz or less. In the embodiment, during the recording operation, the potential of the first magnetic pole 31 is higher than the potential of the second magnetic pole 32. During the recording operation, an element current ic flows through the magnetic element 20 in the direction from the first magnetic pole 31 to the second magnetic pole 32. When the recording current Iw is supplied to the coil 30c and a current flows through the magnetic element 20 in the direction from the second magnetic pole 32 to the first magnetic pole 31 (in Figure 2, when the supplied current ia1 is negative), no alternating magnetic field is generated during the recording operation.

[0044] The above high-frequency signals can be made easier to observe, for example, by changing the current supplied to coil 30c. For example, information about the alternating magnetic field during recording can be easily obtained from the change in the high-frequency signal in response to a change in the current supplied to coil 30c. For example, the high-frequency signals can be made easier to observe by applying an external DC magnetic field. Information about the alternating magnetic field during recording can be easily obtained from the change in the high-frequency signal in response to a change in the DC magnetic field.

[0045] When an alternating electromagnetic force is applied to the magnetic element 20 while supplying a DC applied voltage Va1 (and a DC supply current ia1), the electrical resistance Re1 changes according to the state of the magnetic element 20. The alternating electromagnetic force is, for example, an alternating magnetic field applied from an external source. The alternating electromagnetic force is, for example, a high-frequency signal applied to the magnetic element 20 from the first terminal T1 or the second terminal T2.

[0046] Figure 4 is a schematic cross-sectional view illustrating a part of a magnetic recording device according to the first embodiment. Figure 5 is a schematic plan view illustrating a part of the magnetic recording device according to the first embodiment. As shown in Figure 4, the magnetic element 20 includes a first magnetic layer 21, a second magnetic layer 22, a third magnetic layer 23, and a fourth magnetic layer 24. The first magnetic layer 21 is provided between the first magnetic pole 31 and the second magnetic pole 32. The second magnetic layer 22 is provided between the first magnetic layer 21 and the second magnetic pole 32. The third magnetic layer 23 is provided between the second magnetic layer 22 and the second magnetic pole 32. The fourth magnetic layer 24 is provided between the third magnetic layer 23 and the second magnetic pole 32.

[0047] The magnetic element 20 includes a first non-magnetic layer 41, a second non-magnetic layer 42, a third non-magnetic layer 43, a fourth non-magnetic layer 44, and a fifth non-magnetic layer 45. The first non-magnetic layer 41 is provided between the first magnetic pole 31 and the first magnetic layer 21. The second non-magnetic layer 42 is provided between the first magnetic layer 21 and the second magnetic layer 22. The third non-magnetic layer 43 is provided between the second magnetic layer 22 and the third magnetic layer 23. The fourth non-magnetic layer 44 is provided between the third magnetic layer 23 and the fourth magnetic layer 24. The fifth non-magnetic layer 45 is provided between the fourth magnetic layer 24 and the second magnetic pole 32.

[0048] As shown in Figure 5, in the magnetic head 110, the first magnetic layer 21 and the third magnetic layer 23 are thicker than the second magnetic layer 22 and the fourth magnetic layer 24.

[0049] The direction from the first magnetic pole 31 to the second magnetic pole 32 is defined as the first direction D1. The thickness of the first magnetic layer 21 along the first direction D1 is defined as the first thickness t21. The thickness of the second magnetic layer 22 along the first direction D1 is defined as the second thickness t22. The thickness of the third magnetic layer 23 along the first direction D1 is defined as the third thickness t23. The thickness of the fourth magnetic layer 24 along the first direction D1 is defined as the fourth thickness t24.

[0050] In the magnetic head 110, the first thickness t21 is thicker than the second thickness t22. The first thickness t21 is thicker than the fourth thickness t24. The third thickness t23 is thicker than the second thickness t22. The third thickness t23 is thicker than the fourth thickness t24.

[0051] The first magnetic layer 21 and the third magnetic layer 23 are, for example, oscillation layers. The second magnetic layer 22 and the fourth magnetic layer 24 are, for example, spin injection layers.

[0052] In the magnetic head 110, for example, the first non-magnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer 42 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third non-magnetic layer 43 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fourth non-magnetic layer 44 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth non-magnetic layer 45 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0053] In a first material comprising at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, spins are poorly permeable. In a second material comprising at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, spins are easily permeable.

[0054] In the magnetic head 110, the multiple states described with respect to Figures 2, 3(a), and 3(b) correspond to changes in the magnetization state of the magnetic layer. Examples of magnetization states are described below.

[0055] Figures 6(a) to 6(d) are schematic diagrams illustrating the operation of the magnetic recording device according to the first embodiment. As shown in Figure 6(a), in one example, in the first state ST1, the magnetization 31M of the first magnetic pole 31 and the magnetization 32M of the second magnetic pole 32 are "upward". "Upward" corresponds to the direction from the second magnetic pole 32 to the first magnetic pole 31. In the first state ST1, the magnetization 21M of the first magnetic layer 21, the magnetization 22M of the second magnetic layer 22, the magnetization 23M of the third magnetic layer 23, and the magnetization 24M of the fourth magnetic layer 24 are "upward". "Upward" corresponds to the direction from the second magnetic pole 32 to the first magnetic pole 31. In the examples in Figures 6(a) to 6(d), the direction (polarity) of the recording current Iw corresponds to the "upward" direction.

[0056] As shown in Figure 6(b), when the applied voltage Va1 is the first voltage V1, the magnetization 24M of the fourth magnetic layer 24 is reversed.

[0057] As shown in Figure 6(c), in the second state ST2, the magnetization 21M of the first magnetic layer 21 and the magnetization 23M of the third magnetic layer 23 oscillate. This generates an alternating magnetic field from the magnetic element 20. The magnetizations 21M and 23M oscillate in opposite phases. For example, the phase difference between the Y-axis component of magnetization 21M and the Y-axis component of magnetization 23M is between 160 degrees and 200 degrees. In the second state ST2, a stable oscillation frequency can be obtained due to the opposite-phase oscillation. Appropriate MAMR can be performed.

[0058] As shown in Figure 6(d), in the third state ST3, the magnetization 21M of the first magnetic layer 21 and the magnetization 23M of the third magnetic layer 23 oscillate. In the third state ST3, the oscillations in these magnetic layers are not in opposite phase. For example, the oscillation frequency of magnetization 21M is different from the oscillation frequency of magnetization 23M. In the third state ST3, proper MAMR is difficult due to the oscillations that are not in opposite phase.

[0059] The following describes an example of simulation results for the magnetic head 110. Figures 7(a) and 7(b) are schematic diagrams illustrating the simulation results for a magnetic recording device. The horizontal axis in these figures represents the applied voltage Va1. The vertical axis in Figure 7(a) represents the electrical resistance Re2 of the magnetic element 20. The vertical axis in Figure 7(b) represents the differential resistance Rd2 of the magnetic element 20. In the simulation, the effects of Joule heating are ignored for both the electrical resistance Re2 and the differential resistance Rd2. In the simulation, the effects of thermoelectric effects are ignored.

[0060] As shown in Figure 7(a), the electrical resistance Re2 changes discontinuously in a step-like manner at the first voltage V1 and the second voltage V2.

[0061] As shown in Figure 7(b), at the first voltage V1, the differential resistance Rd2 reaches its first differential resistance peak p1. At the second voltage V2, the differential resistance Rd2 reaches its second differential resistance peak p2.

[0062] Figures 8(a) to 8(c) are schematic diagrams illustrating the simulation results for a magnetic recording device. These figures illustrate the simulation results of the frequency components of the high-frequency signal generated from the magnetic element 20. The horizontal axis represents frequency fr0. Frequency fr0 corresponds to the frequency of the high-frequency signal obtained from the magnetic element 20. Frequency fr0 corresponds to the frequency of the alternating magnetic field obtained from the magnetic element 20. The vertical axis represents the oscillation intensity Int1 (e.g., amplitude) of the electrical resistance of the magnetic element 20. The vertical axis is normalized by the maximum value in each of Figures 8(a) to 8(c). The vertical axis represents the intensity of the high-frequency signal obtained from the magnetic element 20. The vertical axis represents the intensity of the alternating magnetic field.

[0063] Figure 8(a) corresponds to one of the second states ST2. In Figure 8(a), the applied voltage Va1 is the third voltage V3 (see Figures 7(a) and 7(b)). The third voltage V3 is higher than the first voltage V1 and lower than the second voltage V2. When the third voltage V3 is applied, one peak (first frequency peak pf1) is observed. In this example, the first frequency f1 corresponding to the first frequency peak pf1 is approximately 25 GHz.

[0064] In Figure 8(b), the applied voltage Va1 is the fourth voltage V4 (see Figures 7(a) and 7(b)). The fourth voltage V4 is higher than the third voltage V3 and lower than the second voltage V2. As shown in Figure 8(b), when the fourth voltage V4 is applied, a first frequency peak pf1 and a second frequency peak pf2 are observed. In this example, the second frequency f2, which corresponds to the second frequency peak pf2, is approximately 41 GHz.

[0065] Figure 8(c) corresponds to one of the third states ST3. As shown in Figure 8(c), the applied voltage Va1 is the fifth voltage V5 (see Figures 7(a) and 7(b)). The fifth voltage V5 is higher than the second voltage V2. As shown in Figure 8(c), the height of the second frequency peak pf2 is higher than the height of the second frequency peak pf2 in the example of Figure 8(b).

[0066] An alternating magnetic field with a first frequency f1 is used in MAMR. An alternating magnetic field with a second frequency f2 is not needed in MAMR. If the applied voltage Va1 becomes higher than the second voltage V2 (for example, a fifth voltage V5), the second frequency peak pf2 becomes excessively high.

[0067] Figures 9(a) and 9(b) are schematic diagrams illustrating the simulation results for a magnetic recording device. The horizontal axis in Figures 9(a) and 9(b) represents the normalized voltage VR1. The normalized voltage VR1 is the ratio (Va1 / V1) of the applied voltage Va1 to the first voltage V1. The vertical axis in Figure 9(a) represents the oscillation frequency fr21 of the first magnetic layer 21. The oscillation frequency fr21 is the frequency corresponding to the oscillation with maximum intensity in the first magnetic layer 21. The vertical axis in Figure 9(b) represents the oscillation frequency fr23 of the third magnetic layer 23. The oscillation frequency fr23 is the frequency corresponding to the oscillation with maximum intensity in the third magnetic layer 23.

[0068] As shown in Figure 9(a), when the normalized voltage VR1 is 1 or less, oscillation is virtually nonexistent. When the normalized voltage VR1 exceeds 1 (when the applied voltage Va1 exceeds the first voltage V1), the oscillation frequency fr21 in the first magnetic layer 21 increases in a step-like manner. Furthermore, when the applied voltage Va1 exceeds the second voltage V2, the oscillation frequency fr21 in the first magnetic layer 21 increases further in a step-like manner.

[0069] As shown in Figure 9(b), when the normalized voltage VR1 is 1 or less, oscillation is virtually nonexistent. When the normalized voltage VR1 exceeds 1 (when the applied voltage Va1 exceeds the first voltage V1), the oscillation frequency fr23 in the third magnetic layer 23 increases in a step-like manner. Even when the applied voltage Va1 exceeds the second voltage V2, the oscillation frequency fr23 in the third magnetic layer 23 does not increase in a step-like manner.

[0070] When the applied voltage Va1 is higher than the first voltage V1, the second voltage V2 less thanIn this state, the oscillation frequency fr21 in the first magnetic layer 21 is substantially the same as the oscillation frequency fr23 in the third magnetic layer 23. In this state (second state ST2), the magnetization 21M of the first magnetic layer 21 is thought to oscillate in opposite phase to the magnetization 23M of the third magnetic layer 23, in synchronization with it.

[0071] In this second state ST2, the synchronized oscillation of the first magnetic layer 21 and the third magnetic layer 23 allows for, for example, the acquisition of a high-intensity alternating magnetic field at a stable frequency.

[0072] The oscillation frequency fr23 in the region exceeding the first voltage V1, as illustrated in Figure 9(b), corresponds to the first frequency f1, as illustrated in Figure 8(a), etc. The oscillation frequency fr21 in the region exceeding the second voltage V2, as illustrated in Figure 9(a), is thought to correspond to the second frequency f2, as illustrated in Figure 8(c), etc.

[0073] In the region exceeding the second voltage V2 (third state ST3), it is thought that multiple oscillation layers contained in the magnetic element 20 oscillate at different frequencies. This state specifically occurs when multiple oscillation layers are provided. In the second state ST2, the multiple oscillation layers oscillate synchronously, and a single high-intensity oscillation frequency is obtained.

[0074] In the fourth voltage V4 and fifth voltage V5 illustrated in Figures 9(a) and 9(b), it is considered that a second frequency peak pf2 of the second frequency f2 illustrated in Figures 8(a) and 8(c) occurs.

[0075] Figures 10(a) and 10(b) are schematic diagrams illustrating the simulation results for a magnetic recording device. The horizontal axis in these figures represents the normalized voltage VR1. The vertical axis in these figures represents the peak ratio RP1. The peak ratio RP1 is the ratio of the height (intensity) of the second frequency peak to the height (intensity) of the first frequency peak. The vertical axis in Figure 9(b) is an enlarged version of the vertical axis in Figure 9(a).

[0076] As shown in Figures 10(a) and 10(b), when the normalized voltage VR1 exceeds 5.4, the peak ratio RP1 increases sharply. The region in which the peak ratio RP1 increases sharply corresponds to the third state ST3.

[0077] In the embodiment, it is practically preferable that the peak ratio RP1 is 0.1 or less. This suppresses the influence of the second frequency peak pf2, which is not used in MAMR. This allows MAMR using the first frequency peak pf1 to be implemented effectively. Excessively high voltages (excessively large currents) are suppressed, resulting in more stable magnetic head characteristics. For example, a practical magnetic recording device with a long lifespan can be obtained. For example, an excessively large writing area is suppressed. A high recording density can be obtained.

[0078] In this embodiment, the normalized voltage VR1 is preferably less than 5.4. This suppresses the second frequency peak pf2 that is not used by MAMR. In this embodiment, the normalized voltage VR1 is even more preferably 5 or less. This stably suppresses the second frequency peak pf2. In this example, the normalized voltage VR1 is 5.4 at the second voltage V2.

[0079] Thus, when a recording current Iw is supplied to the coil 30c and the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is higher than the second voltage V2, the frequency components of the signal obtained from the magnetic element 20 include a first frequency peak pf1 of the first frequency f1 and a second frequency peak pf2 of the second frequency f2. The second frequency f2 is higher than the first frequency f1.

[0080] In this embodiment, when a recording current Iw is supplied to the coil 30c and the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is the element voltage V20, the frequency components of the signal obtained from the magnetic element 20 include a first frequency peak pf1 but do not include a second frequency peak pf2. Alternatively, the ratio of the height of the second frequency peak pf2 to the height of the first frequency peak pf1 is 0.1 or less.

[0081] In the embodiment, it is preferable that the element voltage V20 is higher than the first voltage V1 and less than 5.4 times the first voltage V1. In the embodiment, it is even more preferable that the element voltage V20 is 5 times or less the first voltage V1.

[0082] When the element voltage V20 described above is applied to the magnetic element 20, a strong alternating magnetic field with a stable frequency is obtained.

[0083] In the embodiment, the second voltage V2, which causes the electrical resistance Re1 to change in a step-like manner, may not be clearly observed. In the embodiment, the second voltage V2 (the voltage at which the second differential resistance peak p2 occurs) may not be clearly observed in the differential resistance Rd1. In this case, the element voltage V20 in the recording operation may be set to less than 5.4 times the first voltage V1.

[0084] As shown in Figure 5, the first non-magnetic layer 41 has a thickness t41. The second non-magnetic layer 42 has a thickness t42. The third non-magnetic layer 43 has a thickness t43. The fourth non-magnetic layer 44 has a thickness t44. The fifth non-magnetic layer 45 has a thickness t45. These thicknesses are the lengths along the first direction D1. At least one of these thicknesses is, for example, between 5 nm and 15 nm.

[0085] Below, several examples of magnetic heads in the magnetic recording device 210 according to the embodiment will be described.

[0086] Figure 11 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. As shown in Figure 11, in the magnetic head 111 according to the embodiment, the magnetic element 20 also includes a first magnetic layer 21, a second magnetic layer 22, a third magnetic layer 23, and a fourth magnetic layer 24. In the magnetic head 111, the first thickness t21 is thicker than the second thickness t22. The first thickness t21 is thicker than the fourth thickness t24. The third thickness t23 is thicker than the second thickness t22. The third thickness t23 is thicker than the fourth thickness t24. The first magnetic layer 21 and the third magnetic layer 23 are, for example, oscillation layers. The second magnetic layer 22 and the fourth magnetic layer 24 are, for example, spin injection layers.

[0087] In the magnetic head 111, the magnetic element 20 includes a first non-magnetic layer 41, a second non-magnetic layer 42, a third non-magnetic layer 43, a fourth non-magnetic layer 44, and a fifth non-magnetic layer 45. In the magnetic head 111, the materials of these non-magnetic layers are different from those of the magnetic head 110.

[0088] In the magnetic head 111, the first non-magnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer 42 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third non-magnetic layer 43 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth non-magnetic layer 44 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth non-magnetic layer 45 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0089] Even in such a magnetic head 111, the element voltage V20 during recording is higher than the first voltage V1 and less than the second voltage V2. For example, the differential resistance Rd1 of the magnetic element 20 reaches its first differential resistance peak p1 when the applied voltage Va1 is the first voltage V1. The differential resistance Rd1 reaches its second differential resistance peak p2 when the applied voltage Va1 is the second voltage V2. The second voltage V2 is higher than twice the first voltage V1.

[0090] In the magnetic head 111 as well, the element voltage V20 during recording operation may be set to less than 5.4 times the first voltage V1.

[0091] In the magnetic head 111 as well, when the recording current Iw is supplied to the coil 30c and the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is the element voltage V20, the frequency components of the signal obtained from the magnetic element 20 include the first frequency peak pf1 but do not include the second frequency peak pf2. Alternatively, the ratio of the height of the second frequency peak pf2 to the height of the first frequency peak pf1 is 0.1 or less.

[0092] Figure 12 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. As shown in Figure 12, in the magnetic head 112 according to the embodiment, the magnetic element 20 also includes a first magnetic layer 21, a second magnetic layer 22, a third magnetic layer 23, and a fourth magnetic layer 24. In the magnetic head 112, the first thickness t21 is thicker than the second thickness t22. The first thickness t21 is thicker than the third thickness t23. The fourth thickness t24 is thicker than the second thickness t22. The fourth thickness t24 is thicker than the third thickness t23. In the magnetic head 112, the first magnetic layer 21 and the fourth magnetic layer 24 are, for example, oscillation layers. The second magnetic layer 22 and the third magnetic layer 23 are, for example, spin injection layers.

[0093] In the magnetic head 112, the magnetic element 20 includes a first non-magnetic layer 41, a second non-magnetic layer 42, a third non-magnetic layer 43, a fourth non-magnetic layer 44, and a fifth non-magnetic layer 45. In the magnetic head 112, the first non-magnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer 42 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third non-magnetic layer 43 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth non-magnetic layer 44 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth non-magnetic layer 45 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0094] Even in such a magnetic head 112, the element voltage V20 during recording is higher than the first voltage V1 and lower than the second voltage V2. For example, the differential resistance Rd1 of the magnetic element 20 reaches its first differential resistance peak p1 when the applied voltage Va1 is the first voltage V1. The differential resistance Rd1 reaches its second differential resistance peak p2 when the applied voltage Va1 is the second voltage V2. The second voltage V2 is higher than the first voltage V1.

[0095] In the magnetic head 112 as well, the element voltage V20 during recording operation may be set to less than 5.4 times the first voltage V1.

[0096] In the magnetic head 112 as well, when the recording current Iw is supplied to the coil 30c and the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is the element voltage V20, the frequency components of the signal obtained from the magnetic element 20 include the first frequency peak pf1 but do not include the second frequency peak pf2. Alternatively, the ratio of the height of the second frequency peak pf2 to the height of the first frequency peak pf1 is 0.1 or less.

[0097] Figure 13 is a schematic plan view illustrating a part of a magnetic recording device according to the first embodiment. As shown in Figure 13, in the magnetic head 113 according to the embodiment, the magnetic element 20 includes a first magnetic layer 21, a second magnetic layer 22, and a third magnetic layer 23. The first magnetic layer 21 is provided between the first magnetic pole 31 and the second magnetic pole 32. The second magnetic layer 22 is provided between the first magnetic layer 21 and the second magnetic pole 32. The third magnetic layer 23 is provided between the second magnetic layer 22 and the second magnetic pole 32. The direction from the first magnetic pole 31 to the second magnetic pole 32 is defined as the first direction D1. The first thickness t21 of the first magnetic layer 21 along the first direction D1 is greater than the third thickness t23 of the third magnetic layer 23 along the first direction D1. The second thickness t22 of the second magnetic layer 22 along the first direction D1 is greater than the third thickness t23. In the magnetic head 113, the first magnetic layer 21 and the second magnetic layer 22 are, for example, oscillation layers. The third magnetic layer 23 is, for example, a spin injection layer.

[0098] In the magnetic head 113, the magnetic element 20 includes a first non-magnetic layer 41, a second non-magnetic layer 42, a third non-magnetic layer 43, and a fourth non-magnetic layer 44. The first non-magnetic layer 41 is provided between the first magnetic pole 31 and the first magnetic layer 21. The second non-magnetic layer 42 is provided between the first magnetic layer 21 and the second magnetic layer 22. The third non-magnetic layer 43 is provided between the second magnetic layer 22 and the third magnetic layer 23. The fourth non-magnetic layer 44 is provided between the third magnetic layer 23 and the second magnetic pole 32.

[0099] In the magnetic head 113, the first non-magnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer 42 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third non-magnetic layer 43 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fourth non-magnetic layer 44 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0100] Even in such a magnetic head 113, the element voltage V20 during recording is higher than the first voltage V1 and lower than the second voltage V2. For example, the differential resistance Rd1 of the magnetic element 20 reaches its first differential resistance peak p1 when the applied voltage Va1 is the first voltage V1. The differential resistance Rd1 reaches its second differential resistance peak p2 when the applied voltage Va1 is the second voltage V2. The second voltage V2 is higher than the first voltage V1.

[0101] In the magnetic head 113 as well, the element voltage V20 during recording operation may be set to less than 5.4 times the first voltage V1.

[0102] In the magnetic head 113, when a recording current Iw is supplied to the coil 30c and the applied voltage Va1 applied between the first terminal T1 and the second terminal T2 is the element voltage V20, the frequency components of the signal obtained from the magnetic element 20 include the first frequency peak pf1 but do not include the second frequency peak pf2. Alternatively, the ratio of the height of the second frequency peak pf2 to the height of the first frequency peak pf1 is 0.1 or less.

[0103] When evaluating the characteristics of the magnetic element 20, a first evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the first evaluation alternating electromagnetic force is higher than the frequency of the alternating magnetic field generated from the magnetic element 20 during recording. The frequency of the first evaluation alternating electromagnetic force is higher than the frequency of the alternating magnetic field generated from the magnetic element 20 in the second state ST2. When such a first evaluation alternating electromagnetic force is applied in the second state ST2, for example, the electrical resistance Re1 changes (increases or decreases). For example, there exists a frequency of the first evaluation alternating electromagnetic force at which the change in electrical resistance Re1 is maximized. The change in electrical resistance Re1 with respect to the frequency of the first evaluation alternating electromagnetic force has, for example, an extremum.

[0104] When evaluating the characteristics of the magnetic element 20, a second evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the second evaluation alternating electromagnetic force is higher than the frequency of the alternating magnetic field generated from the magnetic element 20 in the third state ST3. When such a second evaluation alternating electromagnetic force is applied in the third state ST3, for example, the electrical resistance Re1 changes (increases or decreases). For example, there is a frequency of the second evaluation alternating electromagnetic force at which the change in electrical resistance Re1 is maximized. The change in electrical resistance Re1 with respect to the frequency of the second evaluation alternating electromagnetic force has, for example, an extremum. On the other hand, in the first state ST1, even if a first evaluation alternating electromagnetic force or a second evaluation alternating electromagnetic force is applied, the electrical resistance Re1 does not change substantially. For example, the electrical resistance Re1 does not change with respect to the frequency of the alternating electromagnetic force.

[0105] When evaluating the characteristics of the magnetic element 20, a third evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the third evaluation alternating electromagnetic force is lower than the frequency of the alternating magnetic field generated from the magnetic element 20 during recording. The frequency of the third evaluation alternating electromagnetic force is lower than the frequency of the alternating magnetic field generated from the magnetic element 20 in the second state ST2. When such a third evaluation alternating electromagnetic force is applied in the second state ST2, for example, the electrical resistance Re1 changes (increases or decreases). The direction of the change in electrical resistance Re1 when the third evaluation alternating electromagnetic force is applied is, for example, opposite to the direction of the change in electrical resistance Re1 when the first evaluation alternating electromagnetic force is applied. For example, there exists a frequency of the third evaluation alternating electromagnetic force at which the change in electrical resistance Re1 is maximized. The change in electrical resistance Re1 with respect to the frequency of the third evaluation alternating electromagnetic force has, for example, an extremum.

[0106] When evaluating the characteristics of the magnetic element 20, a fourth evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the fourth evaluation alternating electromagnetic force is lower than the frequency of the alternating magnetic field generated from the magnetic element 20 in the third state ST3. When such a fourth evaluation alternating electromagnetic force is applied in the third state ST3, for example, the electrical resistance Re1 changes (increases or decreases). The direction of the change in electrical resistance Re1 when the fourth evaluation alternating electromagnetic force is applied is, for example, opposite to the direction of the change in electrical resistance Re1 when the second evaluation alternating electromagnetic force is applied. For example, there exists a frequency of the fourth evaluation alternating electromagnetic force at which the change in electrical resistance Re2 is maximized. The change in electrical resistance Re1 with respect to the frequency of the fourth evaluation alternating electromagnetic force has, for example, an extremum. On the other hand, in the first state ST1, even if the third evaluation alternating electromagnetic force or the fourth evaluation alternating electromagnetic force is applied, the electrical resistance Re1 does not change substantially. For example, the electrical resistance Re1 does not change with respect to the frequency of the alternating electromagnetic force.

[0107] When evaluating the characteristics of the magnetic element 20, a fifth evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the fifth evaluation alternating electromagnetic force is substantially the same as the frequency of the alternating magnetic field generated from the magnetic element 20 during the recording operation. The frequency of the fifth evaluation alternating electromagnetic force is substantially the same as the frequency of the alternating magnetic field generated from the magnetic element 20 in the second state ST2. When the fifth evaluation alternating electromagnetic force is applied in the first state ST1 and the second state ST2, for example, the electrical resistance Re1 does not change.

[0108] When evaluating the characteristics of the magnetic element 20, a sixth evaluation alternating electromagnetic force may be applied to the magnetic element 20. The frequency of the sixth evaluation alternating electromagnetic force is substantially the same as the frequency of the alternating magnetic field generated from the magnetic element 20 in the third state ST3. When such a sixth evaluation alternating electromagnetic force is applied in the first state ST1 and the third state ST3, for example, the electrical resistance Re1 does not change.

[0109] From the characteristics of the change in electrical resistance Re1 in response to the first to sixth evaluation alternating electromagnetic forces described above, information regarding the alternating magnetic field generated from the magnetic element 20 during recording can be obtained. At the frequency of the alternating magnetic field in which the above characteristics are obtained, it can be assumed that a high-frequency signal (or alternating magnetic field) is generated from the magnetic element 20.

[0110] (Second Embodiment) In the following embodiments, the magnetic head (such as magnetic head 1110) and its variations described in relation to the first embodiment are applied. An example of when magnetic head 110 is used will be described below.

[0111] Figure 14 is a schematic perspective view illustrating a magnetic recording device according to the second embodiment. As shown in Figure 14, the magnetic head according to the embodiment (for example, magnetic head 110) is used together with a magnetic recording medium 80. In this example, the magnetic head 110 includes a recording unit 60 and a playback unit 70. The recording unit 60 of the magnetic head 110 records information on the magnetic recording medium 80. The playback unit 70 reproduces the information recorded on the magnetic recording medium 80.

[0112] The magnetic recording medium 80 includes, for example, a media substrate 82 and a magnetic recording layer 81 provided on the media substrate 82. The magnetization 83 of the magnetic recording layer 81 is controlled by the recording unit 60.

[0113] The regeneration unit 70 includes, for example, a first regeneration magnetic shield 72a, a second regeneration magnetic shield 72b, and a magnetic regeneration element 71. The magnetic regeneration element 71 is provided between the first regeneration magnetic shield 72a and the second regeneration magnetic shield 72b. The magnetic regeneration element 71 is capable of outputting a signal corresponding to the magnetization 83 of the magnetic recording layer 81.

[0114] As shown in Figure 14, the magnetic recording medium 80 moves relative to the magnetic head 110 in the direction of the medium movement direction 85. The magnetic head 110 controls the information corresponding to the magnetization 83 of the magnetic recording layer 81 at any position. The magnetic head 110 reproduces the information corresponding to the magnetization 83 of the magnetic recording layer 81 at any position.

[0115] Figure 15 is a schematic perspective view illustrating a part of a magnetic recording apparatus according to an embodiment. Figure 15 illustrates a head slider. The magnetic head 110 is mounted on a head slider 159. The head slider 159 includes, for example, Al2O3 / TiC. The head slider 159 moves relative to the magnetic recording medium, either floating above or in contact with it.

[0116] The head slider 159 has, for example, an air inlet side 159A and an air outlet side 159B. The magnetic head 110 is positioned on the side of the air outlet side 159B of the head slider 159. As a result, the magnetic head 110 moves relative to the magnetic recording medium while floating above or in contact with it.

[0117] Figure 16 is a schematic perspective view illustrating a magnetic recording device according to an embodiment. Figures 17(a) and 17(b) are schematic perspective views illustrating a part of a magnetic recording apparatus according to an embodiment. As shown in Figure 16, a rotary actuator is used in the magnetic recording device 150 according to this embodiment. The recording medium disk 180 is mounted on a spindle motor 180M. The recording medium disk 180 rotates in the direction of arrow AR by the spindle motor 180M. The spindle motor 180M responds to a control signal from the drive unit control. The magnetic recording device 150 according to this embodiment may include a plurality of recording medium disks 180. The magnetic recording device 150 may also include a recording medium 181. The recording medium 181 is, for example, an SSD (Solid State Drive). For example, a non-volatile memory such as flash memory is used for the recording medium 181. For example, the magnetic recording device 150 may also be a hybrid HDD (Hard Disk Drive).

[0118] The head slider 159 records and plays back information to be recorded on the recording medium disk 180. The head slider 159 is located at the tip of a thin-film suspension 154. A magnetic head according to this embodiment is located near the tip of the head slider 159.

[0119] As the recording medium disk 180 rotates, the pressing pressure from the suspension 154 and the pressure generated on the media-facing surface (ABS) of the head slider 159 are balanced. The distance between the media-facing surface of the head slider 159 and the surface of the recording medium disk 180 becomes a predetermined amount of levitation. In this embodiment, the head slider 159 may be in contact with the recording medium disk 180. For example, a contact-running type may be applied.

[0120] The suspension 154 is connected to one end of an arm 155 (for example, an actuator arm). The arm 155 has, for example, a bobbin section. The bobbin section holds a drive coil. A voice coil motor 156 is provided at the other end of the arm 155. The voice coil motor 156 is a type of linear motor. The voice coil motor 156 includes, for example, a drive coil and a magnetic circuit. The drive coil is wound around the bobbin section of the arm 155. The magnetic circuit includes a permanent magnet and an opposing yoke. The drive coil is provided between the permanent magnet and the opposing yoke. The suspension 154 has one end and the other end. A magnetic head is provided at one end of the suspension 154. The arm 155 is connected to the other end of the suspension 154.

[0121] The arm 155 is held by ball bearings. Ball bearings are provided at two locations, above and below the bearing portion 157. The arm 155 can rotate and slide by a voice coil motor 156. The magnetic head can move to any position on the recording medium disk 180.

[0122] Figure 17(a) illustrates a part of the configuration of a magnetic recording device and is an enlarged perspective view of the head stack assembly 160. Figure 17(b) is a perspective view illustrating a magnetic head assembly (head gimbal assembly: HGA) 158, which is part of the head stack assembly 160.

[0123] As shown in Figure 17(a), the head stack assembly 160 includes a bearing section 157, a head gimbal assembly 158, and a support frame 161. The head gimbal assembly 158 extends from the bearing section 157. The support frame 161 extends from the bearing section 157. The direction in which the support frame 161 extends is opposite to the direction in which the head gimbal assembly 158 extends. The support frame 161 supports the coil 162 of the voice coil motor 156.

[0124] As shown in Figure 17(b), the head gimbal assembly 158 includes an arm 155 extending from a bearing portion 157 and a suspension 154 extending from the arm 155.

[0125] A head slider 159 is provided at the tip of the suspension 154. A magnetic head according to the embodiment is provided on the head slider 159.

[0126] The magnetic head assembly (head gimbal assembly) 158 according to the embodiment includes a magnetic head according to the embodiment, a head slider 159 on which the magnetic head is provided, a suspension 154, and an arm 155. The head slider 159 is provided at one end of the suspension 154. The arm 155 is connected to the other end of the suspension 154.

[0127] The suspension 154 may have, for example, lead wires (not shown) for recording and reproducing signals. The suspension 154 may also have, for example, lead wires (not shown) for heaters for adjusting the amount of levitation. The suspension 154 may also have, for example, lead wires (not shown) for an oscillator or the like. These lead wires are electrically connected to a plurality of electrodes provided on the magnetic head.

[0128] In the magnetic recording device 150, a signal processing unit 190 is provided. The signal processing unit 190 records and reproduces signals on a magnetic recording medium using a magnetic head. The input and output lines of the signal processing unit 190 are connected, for example, to the electrode pads of the head gimbal assembly 158 and are electrically connected to the magnetic head.

[0129] The magnetic recording apparatus 150 according to the embodiment includes a magnetic recording medium, a magnetic head according to the embodiment, a movable part, a position control unit, and a signal processing unit. The movable part allows the magnetic recording medium and the magnetic head to move relative to each other while separated or in contact. The position control unit aligns the magnetic head to a predetermined recording position on the magnetic recording medium. The signal processing unit records and reproduces signals on the magnetic recording medium using the magnetic head.

[0130] For example, a recording medium disk 180 is used as the magnetic recording medium. The movable part includes, for example, a head slider 159. The position control unit includes, for example, a head gimbal assembly 158.

[0131] The embodiment may include the following configuration (e.g., proposed technical details). (Composition 1) The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. During the recording operation, an alternating magnetic field is generated from the magnetic element. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. A magnetic recording device in which the element voltage is higher than the first voltage and less than the second voltage.

[0132] (Configuration 2) When the applied voltage is higher than the first voltage and lower than the second voltage, the alternating magnetic field is generated from the magnetic element. The magnetic recording apparatus according to configuration 1, wherein the alternating magnetic field is not generated from the magnetic element when the applied voltage is lower than the first voltage.

[0133] (Composition 3) The magnetic recording device according to configuration 1 or 2, wherein the frequency of the alternating magnetic field is 10 GHz or more and 40 GHz or less.

[0134] (Composition 4) A magnetic recording device according to any one of configurations 1 to 3, wherein in the recording operation, the potential of the first magnetic pole is higher than the potential of the second magnetic pole.

[0135] (Composition 5) In the recording operation, an element current flows through the magnetic element in the direction from the first magnetic pole to the second magnetic pole. A magnetic recording apparatus according to any one of configurations 1 to 4, wherein when the recording current is supplied to the coil and a current flows from the second magnetic pole to the first magnetic pole through the magnetic element, the alternating magnetic field is not generated from the magnetic element.

[0136] (Composition 6) When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is higher than the second voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak at the first frequency and a second frequency peak at the second frequency which is higher than the first frequency. A magnetic recording apparatus according to any one of configurations 1 to 5, wherein when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency component includes a first frequency peak and does not include a second frequency peak, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

[0137] (Composition 7) The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. During the recording operation, an alternating magnetic field is generated from the magnetic element. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is higher than the first applied voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak at the first frequency and a second frequency peak at the second frequency which is higher than the first frequency. A magnetic recording device in which, when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency components include a first frequency peak and do not include a second frequency peak, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

[0138] (Composition 8) The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. During the recording operation, an alternating magnetic field is generated from the magnetic element. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is the first voltage. A magnetic recording device in which the element voltage is higher than the first voltage and less than 5.4 times the first voltage.

[0139] (Composition 9) The magnetic recording apparatus according to configuration 8, wherein the element voltage is 5 times or less the first voltage.

[0140] (Composition 10) When the applied voltage is higher than the first voltage, the alternating magnetic field is generated from the magnetic element. The magnetic recording apparatus according to configuration 8 or 9, wherein the alternating magnetic field is not generated from the magnetic element when the applied voltage is lower than the first voltage.

[0141] (Composition 11) The magnetic recording device according to any one of configurations 8 to 10, wherein the frequency of the alternating magnetic field is 10 GHz or more and 40 GHz or less.

[0142] (Composition 12) The magnetic recording apparatus according to any one of configurations 8 to 11, wherein in the recording operation, the potential of the first magnetic pole is higher than the potential of the second magnetic pole.

[0143] (Composition 13) In the recording operation, an element current flows through the magnetic element in the direction from the first magnetic pole to the second magnetic pole. A magnetic recording apparatus according to any one of configurations 8 to 12, wherein when the recording current is supplied to the coil and a current flows from the second magnetic pole to the first magnetic pole through the magnetic element, the alternating magnetic field is not generated from the magnetic element.

[0144] (Composition 14) The aforementioned magnetic circuit is A first magnetic layer provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, A fourth magnetic layer is provided between the third magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the second thickness of the second magnetic layer along the first direction, and greater than the fourth thickness of the fourth magnetic layer along the first direction. A magnetic recording apparatus according to any one of configurations 1 to 13, wherein the third thickness of the third magnetic layer along the first direction is greater than the second thickness and greater than the fourth thickness.

[0145] (Composition 15) The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer is provided between the fourth magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second nonmagnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fourth nonmagnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to configuration 14, wherein the fifth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0146] (Composition 16) The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer is provided between the fourth magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third nonmagnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth nonmagnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to configuration 14, wherein the fifth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0147] (Composition 17) The aforementioned magnetic circuit is A first magnetic layer provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, A fourth magnetic layer is provided between the third magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the second thickness of the second magnetic layer along the first direction, and greater than the third thickness of the third magnetic layer along the first direction. A magnetic recording apparatus according to any one of configurations 1 to 13, wherein the fourth thickness of the fourth magnetic layer along the first direction is thicker than the second thickness and thicker than the third thickness.

[0148] (Composition 18) The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer is provided between the fourth magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third nonmagnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth nonmagnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to configuration 17, wherein the fifth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0149] (Composition 19) The aforementioned magnetic circuit is A first magnetic layer provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the third thickness of the third magnetic layer along the first direction. A magnetic recording apparatus according to any one of configurations 1 to 13, wherein the second thickness of the second magnetic layer along the first direction is greater than the third thickness.

[0150] (Composition 20) The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second nonmagnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to configuration 19, wherein the fourth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0151] (Composition 21) The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. During the recording operation, an alternating magnetic field is generated from the magnetic element. A magnetic recording device in which, when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak of a first frequency, and the frequency components do not include a second frequency peak of a second frequency higher than the first frequency, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

[0152] (Composition 22) The magnetic recording apparatus according to configuration 21, wherein when the applied voltage is higher than the element voltage, the frequency component includes the second frequency peak.

[0153] According to this embodiment, a magnetic recording device capable of improving recording density can be provided.

[0154] In this specification, "perpendicular" and "parallel" do not mean strictly perpendicular and strictly parallel, but also include variations in the manufacturing process, for example, and it is sufficient if they are substantially perpendicular and substantially parallel.

[0155] Embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, the specific configuration of each element included in the magnetic head and magnetic recording device, such as magnetic poles, magnetic elements, magnetic layers, non-magnetic layers, and control units, is included within the scope of the present invention as long as those skilled in the art can appropriately select from the known range to implement the present invention and obtain similar effects.

[0156] Combinations of two or more elements from any of the specific examples, to the extent technically feasible, are also included within the scope of the present invention, insofar as they encompass the gist of the invention.

[0157] Furthermore, all magnetic recording devices that can be implemented by those skilled in the art by appropriately modifying the design based on the magnetic recording device described above as an embodiment of the present invention also fall within the scope of the present invention, insofar as they encompass the gist of the present invention.

[0158] Furthermore, within the scope of the concept of the present invention, a person skilled in the art could conceive of various modifications and alterations, and it is understood that such modifications and alterations also fall within the scope of the present invention.

[0159] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0160] 20...Magnetic element, 20D...Element circuit, 21~24...1st to 4th magnetic layers, 21M~24M...Magnetization, 30D...Recording circuit, 30F...Media-facing surface, 30c...Coil, 30i...Insulation part, 31, 32...1st and 2nd magnetic poles, 31M, 32M...Magnetization, 33...Shield, 41~45...1st to 5th non-magnetic layers, 60...Recording section, 70...Reproduction section, 71...Magnetic reproduction element, 72a, 72b...1st and 2nd reproduction magnetic shields, 75...Control unit, 80...Magnetic recording medium, 81...Magnetic recording layer, 82...Media substrate, 83...Magnetization, 85...Media movement direction, 110~113...Magnetic head, 150...Magnetic recording device, 154...Suspension, 155...Arm 156…Voice coil motor, 157…Bearing section, 158…Head gimbal assembly, 159…Head slider, 159A…Air inlet side, 159B…Air outlet side, 160…Head stack assembly, 161…Support frame, 162…Coil, 180…Recording medium disk, 180M…Spindle motor, 181…Recording medium, 190…Signal processing unit, 210…Magnetic recording device, AR…Arrow, D1…First direction, Int1…Intensity, Iw…Recording current, Rd1, Rd2…Differential resistance, Re1, Re2…Electrical resistance, ST1~ST3…First to third states, T1, T2…First and second terminals, Tc1, Tc2…First and second coil terminals, V1~V5…First to fifth voltages, V20…Element voltage, Va1…Applied voltage, W1, W2…1st and 2nd wiring, f1, f2…1st and 2nd frequencies, fr0…frequency, fr21, fr23…oscillation frequency, i1, i2…1st and 2nd currents, ia1…supply current, ic…element current, je…electron current, p1, p2…1st and 2nd differential resistance peaks, pf1, pf2…1st and 2nd frequency peaks, t21~t24…1st to 4th thicknesses, t41~t45…thickness

Claims

1. The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. During the recording operation, an alternating magnetic field is generated from the magnetic element. When the applied voltage is higher than the first voltage and lower than the second voltage, the alternating magnetic field is generated from the magnetic element. A magnetic recording device in which, when the applied voltage is lower than the first voltage, the alternating magnetic field is not generated from the magnetic element.

2. The first magnetic pole and The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. During the recording operation, an alternating magnetic field is generated from the magnetic element. In the recording operation, an element current flows through the magnetic element in the direction from the first magnetic pole to the second magnetic pole. A magnetic recording device in which, when the recording current is supplied to the coil and a current flows through the magnetic element in the direction from the second magnetic pole to the first magnetic pole, the alternating magnetic field is not generated from the magnetic element.

3. The first magnetic pole and The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is higher than the second voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak of the first frequency and a second frequency peak of the second frequency which is higher than the first frequency. A magnetic recording device in which, when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency components include a first frequency peak and do not include a second frequency peak, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

4. The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is higher than the first applied voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak at the first frequency and a second frequency peak at the second frequency which is higher than the first frequency. A magnetic recording device in which, when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency components include a first frequency peak and do not include a second frequency peak, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

5. The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is the first voltage. A magnetic recording device in which the element voltage is higher than the first voltage and less than 5.4 times the first voltage.

6. The first magnetic pole and The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. The aforementioned magnetic circuit is A first magnetic layer is provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, A fourth magnetic layer is provided between the third magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the second thickness of the second magnetic layer along the first direction, and greater than the fourth thickness of the fourth magnetic layer along the first direction. A magnetic recording device in which the third thickness of the third magnetic layer along the first direction is greater than the second thickness and greater than the fourth thickness.

7. The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer is provided between the fourth magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fourth non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to claim 6, wherein the fifth non-magnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

8. The aforementioned magnetic circuit is A first non-magnetic layer is provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer is provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer is provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer is provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer is provided between the fourth magnetic layer and the second magnetic pole, Includes, The first non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third non-magnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth non-magnetic layer comprises at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The magnetic recording apparatus according to claim 6, wherein the fifth non-magnetic layer comprises at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

9. The first magnetic pole and The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. The aforementioned magnetic circuit is A first magnetic layer is provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, A fourth magnetic layer is provided between the third magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the second thickness of the second magnetic layer along the first direction, and greater than the third thickness of the third magnetic layer along the first direction. A magnetic recording device in which the fourth thickness of the fourth magnetic layer along the first direction is greater than the second thickness and greater than the third thickness.

10. A first magnetic pole and The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. When the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is changed, the differential resistance of the magnetic element reaches a first differential resistance peak when the applied voltage is a first voltage, and reaches a second differential resistance peak when the applied voltage is a second voltage, and the second voltage is higher than the first voltage. The element voltage is higher than the first voltage and less than the second voltage. The aforementioned magnetic circuit is A first magnetic layer is provided between the first magnetic pole and the second magnetic pole, A second magnetic layer is provided between the first magnetic layer and the second magnetic pole, A third magnetic layer is provided between the second magnetic layer and the second magnetic pole, Includes, The first thickness of the first magnetic layer along the first direction from the first magnetic pole to the second magnetic pole is greater than the third thickness of the third magnetic layer along the first direction. A magnetic recording device in which the second thickness of the second magnetic layer along the first direction is greater than the third thickness.

11. The first magnetic pole and, The second magnetic pole and, A magnetic element provided between the first magnetic pole and the second magnetic pole, A first terminal electrically connected to one end of the magnetic element, A second terminal electrically connected to the other end of the magnetic element, Coil and, A magnetic head including, A control unit electrically connected to the magnetic element and the coil, Equipped with, The control unit is capable of recording operations, The control unit, in the recording operation, supplies a recording current to the coil while applying an element voltage between the first terminal and the second terminal. A magnetic recording device in which, when the recording current is supplied to the coil and the applied voltage applied between the first terminal and the second terminal is the element voltage, the frequency components of the signal obtained from the magnetic element include a first frequency peak of a first frequency, and the frequency components do not include a second frequency peak of a second frequency higher than the first frequency, or the ratio of the height of the second frequency peak to the height of the first frequency peak is 0.1 or less.

12. The magnetic recording apparatus according to claim 11, wherein when the applied voltage is higher than the element voltage, the frequency component includes the second frequency peak.

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