Magnetic head and magnetic recording device

Abstract

To provide a magnetic head and a magnetic recording device capable of improving characteristics.SOLUTION: A magnetic head 110 includes a first magnetic pole 31, a second magnetic pole 32, and a magnetic element 20. The magnetic element 20 is provided between the first magnetic pole 31 and the second magnetic pole 32 in a first direction D1 from the first magnetic pole 31 to the second magnetic pole 32. The magnetic element 20 includes a first magnetic layer 21 provided between the first magnetic pole 31 and the second magnetic pole 32, a second magnetic layer 22 provided between the first magnetic layer 21 and the second magnetic pole 32, a third magnetic layer 23 provided between the second magnetic layer 22 and the second magnetic pole 32, and a fourth magnetic layer 24 provided between the third magnetic layer 23 and the second magnetic pole 32. The first magnetic layer 21 includes a first surface F1 facing the first magnetic pole 32. The fourth magnetic layer 24 includes a second surface F2 facing the second magnetic pole 32. A first area of the first surface F1 is greater than a second area of the second surface F2.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Information is recorded on a magnetic recording medium such as an HDD (Hard Disk Drive) using a magnetic head. In the magnetic head, improvement in characteristics 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 head and a magnetic recording device capable of improving characteristics.

Means for Solving the Problems

[0005] According to an embodiment, the magnetic head includes a first magnetic pole, a second magnetic pole, and a magnetic element. The magnetic element is provided between the first magnetic pole and the second magnetic pole in a first direction from the first magnetic pole to the second magnetic pole. The magnetic element includes a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, and a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole. The first magnetic layer includes a first surface facing the first magnetic pole. The fourth magnetic layer includes a second surface facing the second magnetic pole. A first area of the first surface is larger than a second area of the second surface.

Brief Description of the Drawings

[0006]

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DETAILED DESCRIPTION OF THE INVENTION

[0007] (First Embodiment) FIG. 1 is a schematic plan view illustrating the magnetic head according to the first embodiment. FIG. 2 is a schematic cross-sectional view illustrating the magnetic recording apparatus including the magnetic head according to the first embodiment.

[0008] As shown in FIG. 2, the magnetic recording apparatus 210 according to the embodiment includes a magnetic head 110 and a magnetic recording medium 80. The magnetic recording apparatus 210 may further include a control unit 75. In the magnetic recording apparatus 210, at least a recording operation is performed. In the recording operation, information is recorded on the magnetic recording medium 80 using the magnetic head 110.

[0009] The magnetic head 110 includes a recording unit 60. As will be described later, the magnetic head 110 may include a reproducing unit. The recording unit 60 includes a first magnetic pole 31, a second magnetic pole 32, and a magnetic element 20. The recording unit 60 may further include a coil 30c. The magnetic element 20 is provided between the first magnetic pole 31 and the second magnetic pole 32.

[0010] 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. The first magnetic pole 31 may be a trailing shield and the second magnetic pole 32 may be a main magnetic pole.

[0011] 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 both 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. At a desired position on the magnetic recording medium 80, a recording magnetic field generated from the magnetic head 110 is applied. 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.

[0012] 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, more than 0 degrees and 10 degrees or less.

[0013] 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).

[0014] As shown in FIG. 2, a recording current Iw is supplied from the recording circuit 30D to the 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 the first magnetic pole 31, a recording magnetic field corresponding to the recording current Iw is applied to the magnetic recording medium 80.

[0015] As shown in FIG. 2, 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.

[0016] As shown in FIG. 2, the element circuit 20D is electrically connected to the magnetic element 20. In this example, the magnetic element 20 is electrically connected to the first magnetic pole 31 and the second magnetic pole 32. The magnetic head 110 is provided with a first terminal T1 and a second terminal T2. The first terminal T1 is electrically connected to one end of the magnetic element 20 via the 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 via the second wiring W2 and the second magnetic pole 32. For example, an element current ic is supplied from the element circuit 20D to the magnetic element 20.

[0017] As shown in FIG. 2, in one operating state, the element current ic has a direction from the first magnetic pole 31 to the second magnetic pole 32. In this case, the electron flow je associated with the element current ic has a direction from the second magnetic pole 32 to the first magnetic pole 31. The element current ic is, for example, a direct current. As will be described later, in another operating state, the element current ic has a direction from the second magnetic pole 32 to the first magnetic pole 31. In this case, the electron flow je has a direction from the first magnetic pole 31 to the second magnetic pole 32.

[0018] For example, when an element current ic equal to or greater than a threshold value flows through the magnetic element 20, oscillation occurs in the magnetic layer included in the magnetic element 20. The magnetic element 20 functions as, for example, an 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.

[0019] The control unit 75 controls the recording circuit 30D and the element circuit 20D.

[0020] As shown in FIG. 1, 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 a first magnetic pole 31 and a 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.

[0021] The magnetic element 20 may include 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.

[0022] As shown in FIG. 1, the first magnetic layer 21 includes a first surface F1 facing the first magnetic pole 31. The fourth magnetic layer 24 includes a second surface F2 facing the second magnetic pole 32. In an embodiment, the first area of the first surface F1 is larger than the second area of the second surface F2.

[0023] For example, the side surface of the magnetic element 20 is inclined with respect to the first direction D1. As shown in FIG. 2, the first magnetic pole 31 includes a medium-facing surface 30F. As shown in FIG. 1, a first length L1 along a second direction D2 of the first surface F1 is longer than a second length L2 along the second direction D2 of the second surface F2. The second direction D2 is along the medium-facing surface 30F and is orthogonal to the first direction D1. The second direction D2 is, for example, the Y-axis direction. Such a difference in length may cause the above-described difference in area.

[0024] As will be described below, due to such a difference in area (or a difference in length), in the magnetic element 20, a high-speed magnetization reversal can be obtained. A high-speed writing operation can be performed. According to the embodiment, a magnetic head with improved characteristics can be provided. For example, a high recording density can be obtained.

[0025] As shown in FIG. 1, the first surface F1 includes a first end 21a and a first other end 21b. The direction from the first other end 21b to the first end 21a is along the second direction D2. The second surface F2 includes a second end 24a and a second other end 24b. The direction from the second other end 24b to the second end 24a is along the second direction D2. The distance between the first end 21a and the second end 24a is shorter than the distance between the first end 21a and the second other end 24b. The first end 21a and the second end 24a are ends on the same side in the second direction D2. The first other end 21b and the second other end 24b are ends on the same side in the second direction D2.

[0026] Let the straight line passing through the first end 21a and the second end 24a be the first straight line Ln1. The first straight line Ln1 is inclined with respect to the direction perpendicular to the first surface F1 (the first direction D1). Let the angle between the first straight line Ln1 and the direction perpendicular to the first surface F1 (the first direction D1) be the first angle θ1. The first angle θ1 is greater than 0.

[0027] Let the straight line passing through the first other end 21b and the second other end 24b be the second straight line Ln2. The second straight line Ln2 is inclined with respect to the direction perpendicular to the first surface F1 (the first direction D1). Let the angle between the second straight line Ln2 and the direction perpendicular to the second surface F2 (the first direction D1) be the second angle θ2. The second angle θ2 is greater than 0.

[0028] Due to such first angle θ1 and second angle θ2, the above-described difference in area and the above-described difference in length may occur. The second angle θ2 may be substantially the same as the first angle θ1. In the embodiment, the first angle θ1 may be, for example, 5 degrees or more and 15 degrees or less. The second angle θ2 may be, for example, 5 degrees or more and 15 degrees or less.

[0029] Hereinafter, an example of the operation in the magnetic head 110 will be described. Figs. 3(a) to 3(d) are schematic plan views illustrating the operating states of the magnetic head according to the first embodiment. In the magnetic head 110, a first operation OP1 and a second operation OP2 are performed. In the first operation OP1, the element current ic flows from the first magnetic pole 31 to the second magnetic pole 32. In the second operation OP2, the element current ic flows from the second magnetic pole 32 to the first magnetic pole 31. In both the first operation OP1 and the second operation OP2, the magnetization of the magnetic element 20 oscillates.

[0030] On the other hand, a gap magnetic field Hg is generated between the first magnetic pole 31 and the second magnetic pole 32 by a recording magnetic field based on the recording current Iw supplied to the coil 30c. The direction of the recording current Iw changes according to the information to be recorded. Thereby, the direction of the gap magnetic field Hg changes.

[0031] In the first configuration CF1 shown in Fig. 3(a), in the first operation OP1, the gap magnetic field Hg has a direction from the second magnetic pole 32 to the first magnetic pole 31. In the second configuration CF2 shown in Fig. 3(b), in the first operation OP1, the gap magnetic field Hg has a direction from the first magnetic pole 31 to the second magnetic pole 32. In the third configuration CF3 shown in Fig. 3(c), in the second operation OP2, the gap magnetic field Hg has a direction from the second magnetic pole 32 to the first magnetic pole 31. In the fourth configuration CF4 shown in Fig. 3(d), in the second operation OP2, the gap magnetic field Hg has a direction from the first magnetic pole 31 to the second magnetic pole 32.

[0032] In the first operation OP1, a transition occurs between the first configuration CF1 and the second configuration CF2. In the second operation OP2, a transition occurs between the third configuration CF3 and the fourth configuration CF4. It is desirable that these transitions be performed in a short time.

[0033] Fig. 4 is a graph illustrating the characteristics of the magnetic head of the reference example. Figure 4 illustrates the simulation results of the characteristics of the magnetic head 119 of the reference example. In the magnetic head 119, the first angle θ1 and the second angle θ2 are 0, and the first area of the first surface F1 is the same as the second area of the second surface F2. The horizontal axis in Figure 4 is the time tm. The vertical axis is the oscillation intensity SR1 (relative value) of the magnetic layer.

[0034] In the first operation OP1, when the time tm is 0, the switching from the first configuration CF1 to the second configuration CF2 or the switching from the second configuration CF2 to the first configuration CF1 is performed. In the second operation OP2, when the time tm is 0, the switching from the third configuration CF3 to the fourth configuration CF4 or the switching from the fourth configuration CF4 to the third configuration CF3 is performed.

[0035] As shown in Figure 4, in the first operation OP1 and the second operation OP2, when the time tm is about 0.2 ns, the oscillation intensity SR1 is low. When the time tm is 0.6 ns or more, a high oscillation intensity SR1 can be obtained. In this example, for example, the switching time is about 0.6 ns.

[0036] In the time range where the time tm is 0 ns or more and 0.5 ns or less, in the first operation OP1, the oscillation intensity SR1 is low. On the other hand, in this time range, in the second operation OP2, a higher oscillation intensity SR1 than that in the first operation OP1 can be obtained. In the time range where the time tm is 0.6 ns or more, the oscillation intensity SR1 in the first operation OP1 is higher than the oscillation intensity SR1 in the second operation OP2.

[0037] Thus, in the second operation OP2, although a relatively high oscillation intensity SR1 can be obtained at the initial stage of switching, the oscillation intensity SR1 is relatively low after a long time from switching. On the contrary, in the first operation OP1, although the oscillation intensity SR1 is relatively low at the initial stage of switching, a high oscillation intensity SR1 can be obtained after a long time from switching.

[0038] Hereinafter, an example of the simulation results for the oscillation intensity SR1 when the first angle θ1 is changed will be described. In the following example, the second angle θ2 is the same as the first angle θ1.

[0039] Figures 5 and 6 are graphs illustrating the characteristics of the magnetic head. The horizontal axis of these figures is the first angle θ1. When the first angle θ1 is positive, the first area of the first surface F1 is larger than the second area of the second surface F2. When the first angle θ1 is negative, the side surface of the magnetic element 20 shows an opposite inclination, and the first area of the first surface F1 is smaller than the second area of the second surface F2. In Figure 5, the time tm is 0.375 ns. In Figure 6, the time tm is 0.875 ns.

[0040] As shown in Figure 5, as the first angle θ1 becomes larger than 0 degrees, the oscillation intensity SR1 in the second operation OP2 increases. On the other hand, the oscillation intensity SR1 in the first operation OP1 does not change significantly with the change of the first angle θ1. When the first angle θ1 is larger than 5 degrees, a high oscillation intensity SR1 can be effectively obtained in the second operation OP2. The first angle θ1 is preferably, for example, 5 degrees or more.

[0041] As shown in Figure 6, in this example, as the first angle θ1 becomes larger than 0 degrees, the oscillation intensity SR1 in the second operation OP2 increases. On the other hand, the oscillation intensity SR1 in the first operation OP1 decreases when the first angle θ1 exceeds 15 degrees. In an embodiment, the first angle θ1 is preferably 15 degrees or less.

[0042] When the first angle θ1 is 5 degrees or more and 15 degrees or less, a high oscillation intensity SR1 can be obtained in both the first operation OP1 and the second operation OP2.

[0043] When the first angle θ1 is larger than 0, it is considered that the increase in the oscillation intensity SR1 in the second operation OP2 at the time tm of 0.375 ns is due to the appropriate control of the current density in the plurality of magnetic layers included in the magnetic element 20.

[0044] For example, when the first angle θ1 is greater than 0, the current density in the third magnetic layer 23 becomes higher than the current density in the first magnetic layer 21. As a result, for example, oscillation of the magnetization of the third magnetic layer 23 is likely to occur promptly after switching. For example, since the current density in the first magnetic layer 21 is low, it becomes difficult for the magnetization of the first magnetic layer 21 to move, and inhibition of the oscillation of the third magnetic layer 23 is suppressed. For example, the oscillation intensity SR1 in the second operation OP2 is greatly contributed by the oscillation of the magnetization of the third magnetic layer 23.

[0045] Hereinafter, some examples regarding the configuration of the magnetic element 20 will be described. FIGS. 7 to 10 are schematic plan views illustrating a magnetic head according to the first embodiment. As shown in FIG. 7, in the magnetic head 110 according to the embodiment, the magnetic element 20 includes a first nonmagnetic layer 41, a second nonmagnetic layer 42, a third nonmagnetic layer 43, a fourth nonmagnetic layer 44, and a fifth nonmagnetic layer 45.

[0046] In the magnetic head 110, the first nonmagnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second nonmagnetic layer 42 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The third nonmagnetic layer 43 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fourth nonmagnetic layer 44 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth nonmagnetic layer 45 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0047] As shown in FIG. 1, let the thickness along the first direction D1 of the first magnetic layer 21 be the first thickness t21. Let the thickness along the first direction D1 of the second magnetic layer 22 be the second thickness t22. Let the thickness along the first direction D1 of the third magnetic layer 23 be the third thickness t23. Let the thickness along the first direction D1 of the fourth magnetic layer 24 be the fourth thickness t24.

[0048] In the magnetic head 110, the first thickness t21 is thicker than the second thickness t22. The third thickness t23 is thicker than the fourth thickness t24. The first thickness t21 is, for example, 3 nm or more and 15 nm or less. The first thickness t21 may be, for example, 5 nm or more and 15 nm or less. The second thickness t22 is, for example, 1 nm or more and 8 nm or less. The second thickness t22 may be, for example, 1 nm or more and 4 nm or less. The third thickness t23 is, for example, 3 nm or more and 15 nm or less. The third thickness t23 may be, for example, 5 nm or more and 15 nm or less. The fourth thickness t24 is, for example, 1 nm or more and 8 nm or less. The fourth thickness t24 may be, for example, 1 nm or more and 4 nm or less.

[0049] In the magnetic head 111 illustrated in FIG. 8 according to the embodiment, the first nonmagnetic layer 41 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second nonmagnetic layer 42 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third nonmagnetic layer 43 contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth nonmagnetic layer 44 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth nonmagnetic layer 45 contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0050] In the magnetic head 111, the first thickness t21 is thicker than the second thickness t22. The third thickness t23 is thicker than the fourth thickness t24. The first thickness t21 is, for example, 3 nm or more and 15 nm or less. The first thickness t21 may be, for example, 5 nm or more and 15 nm or less. The second thickness t22 is, for example, 1 nm or more and 8 nm or less. The second thickness t22 may be, for example, 1 nm or more and 4 nm or less. The third thickness t23 is, for example, 3 nm or more and 15 nm or less. The third thickness t23 may be, for example, 5 nm or more and 15 nm or less. The fourth thickness t24 is, for example, 1 nm or more and 8 nm or less. The fourth thickness t24 may be, for example, 1 nm or more and 4 nm or less.

[0051] In the magnetic head 112 according to the embodiment illustrated in FIG. 9, the first nonmagnetic layer 41 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second nonmagnetic layer 42 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third nonmagnetic layer 43 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth nonmagnetic layer 44 includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth nonmagnetic layer 45 includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0052] In the magnetic head 112, the first thickness t21 is thicker than the second thickness t22. The third thickness t23 is thinner than the fourth thickness t24. The first thickness t21 is, for example, 3 nm or more and 15 nm or less. The first thickness t21 may be, for example, 5 nm or more and 15 nm or less. The second thickness t22 is, for example, 1 nm or more and 8 nm or less. The second thickness t22 may be, for example, 1 nm or more and 4 nm or less. The third thickness t23 is, for example, 1 nm or more and 8 nm or less. The third thickness t23 may be, for example, 1 nm or more and 4 nm or less. The fourth thickness t24 is, for example, 3 nm or more and 15 nm or less. The fourth thickness t24 may be, for example, 5 nm or more and 15 nm or less.

[0053] In the magnetic heads 110, 111, and 112, the first nonmagnetic layer 41 is in contact with the first magnetic pole 31 and the first magnetic layer 21. The second nonmagnetic layer 42 is in contact with the first magnetic layer 21 and the second magnetic layer 22. The third nonmagnetic layer 43 is in contact with the second magnetic layer 22 and the third magnetic layer 23. The fourth nonmagnetic layer 44 is in contact with the third magnetic layer 23 and the fourth magnetic layer 24. The fifth nonmagnetic layer 45 is in contact with the fourth magnetic layer 24 and the second magnetic pole 32.

[0054] In the magnetic head 113 according to the embodiment illustrated in FIG. 10, the magnetic element 20 further includes a fifth magnetic layer 25 and a sixth nonmagnetic layer 46. The configuration of the magnetic head 113 excluding this may be the same as that of the magnetic head 110, for example.

[0055] In the magnetic head 113, the fifth magnetic layer 25 is provided between the third non-magnetic layer 43 and the third magnetic layer 23. The sixth non-magnetic layer 46 is provided between the fifth magnetic layer 25 and the third magnetic layer 23.

[0056] In the magnetic head 113, the first non-magnetic layer 41 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The second non-magnetic layer 42 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The third non-magnetic layer 43 contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The fourth non-magnetic layer 44 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag. The fifth non-magnetic layer 45 contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W. The sixth non-magnetic layer 46 contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag.

[0057] As shown in FIG. 10, in the magnetic head 113, the thickness along the first direction D1 of the fifth magnetic layer 25 is defined as the fifth thickness t25. As shown in FIG. 1, the first thickness t21, the second thickness t22, the third thickness t23, and the fourth thickness t24 are defined. In the magnetic head 113, the first thickness t21 is thicker than the second thickness t22. The third thickness t23 is thicker than the fourth thickness t24. The fifth thickness t25 is thinner than the third thickness t23. The first thickness t21 is, for example, 3 nm or more and 15 nm or less. The first thickness t21 may be, for example, 5 nm or more and 15 nm or less. The second thickness t22 is, for example, 1 nm or more and 8 nm or less. The second thickness t22 may be, for example, 1 nm or more and 4 nm or less. The third thickness t23 is, for example, 3 nm or more and 15 nm or less. The third thickness t23 may be, for example, 5 nm or more and 15 nm or less. The fourth thickness t24 is, for example, 1 nm or more and 8 nm or less. The fourth thickness t24 may be, for example, 1 nm or more and 4 nm or less. The fifth thickness t25 is, for example, 1 nm or more and 8 nm or less. The fifth thickness t25 may be, for example, 1 nm or more and 4 nm or less.

[0058] In the magnetic heads 111, 112, and 113, the configuration described with respect to the magnetic head 110 may be applied. For example, the first area of the first surface F1 is larger than the second area of the second surface F2. For example, the first length L1 is longer than the second length L2. The first angle θ1 is 5 degrees or more and 15 degrees or less. The second angle θ2 is 5 degrees or more and 15 degrees or less.

[0059] In the magnetic heads 110 to 113, the thickness t41 (see FIG. 1) of the first nonmagnetic layer 41 is, for example, 0.5 nm or more and 6 nm or less. The thickness t42 (see FIG. 1) of the second nonmagnetic layer 42 is, for example, 0.5 nm or more and 10 nm or less. The thickness t43 (see FIG. 1) of the third nonmagnetic layer 43 is, for example, 0.5 nm or more and 10 nm or less. The thickness t44 (see FIG. 1) of the fourth nonmagnetic layer 44 is, for example, 0.5 nm or more and 6 nm or less. The thickness t45 (see FIG. 1) of the fifth nonmagnetic layer 45 is, for example, 1 nm or more and 10 nm or less. The thickness t46 (see FIG. 10) of the sixth nonmagnetic layer 46 is, for example, 0.5 nm or more and 6 nm or less.

[0060] In an embodiment, the first operation OP1 and the second operation OP2 may be performed. These operations may be switched and performed. In the first operation OP1, the element current ic supplied between the first magnetic pole 31 and the second magnetic pole 32 flows from the first magnetic pole 31 to the second magnetic pole 32. In the second operation OP2, the element current ic flows from the second magnetic pole 32 to the first magnetic pole 31.

[0061] Hereinafter, the differential electrical resistance of the magnetic element 20 when the voltage Va1 applied to the magnetic element 20 is changed is exemplified.

[0062] FIGS. 11 to 14 are graphs illustrating the characteristics of the magnetic head according to the first embodiment. The horizontal axis of these figures is the voltage Va1 applied to the magnetic element 20. The vertical axis is the differential electrical resistance Rd1 of the magnetic element 20. The voltage Va1 may be the voltage between the first terminal T1 and the second terminal T2. For example, the voltage corresponding to the voltage Va1 is applied to the magnetic element 20.

[0063] When the voltage Va1 is positive, the potential of the first magnetic pole 31 is higher than the potential of the second magnetic pole 32. When the voltage Va1 is negative, the potential of the first magnetic pole 31 is lower than the potential of the second magnetic pole 32. When the voltage Va1 is positive, the first operation OP1 is performed. When the voltage Va1 is negative, the second operation OP2 is performed.

[0064] As shown in FIG. 11, in the magnetic head 110, the differential electrical resistance Rd1 when the voltage Va1 is changed includes a plurality of peaks. These peaks are considered to correspond to discontinuous changes in electrical resistance accompanying the reversal of magnetization of a plurality of magnetic layers included in the magnetic element 20.

[0065] In the magnetic head 110, the plurality of peaks include a first negative peak n1 and a first positive peak p1. The voltage Va1 corresponding to the first negative peak n1 is the first negative peak voltage Vn1. The voltage Va1 corresponding to the first positive peak p1 is the first positive peak voltage Vp1. In the first operation OP1, the voltage Va1 is in the first voltage range Ve1. The first voltage range Ve1 is, for example, higher than the first positive peak voltage Vp1. In the second operation OP2, the voltage Va1 is in the second voltage range Ve2. The second voltage range Ve2 is, for example, lower than the first negative peak voltage Vn1.

[0066] FIG. 12 corresponds to the magnetic head 111. In the magnetic head 111, the plurality of peaks include a first positive peak p1 and a second positive peak p2. The voltage Va1 corresponding to the second positive peak p2 is the second positive peak voltage Vp2. The second positive peak voltage Vp2 is higher than the first positive peak voltage Vp1. In the first operation OP1, the voltage Va1 is in the first voltage range Ve1. The first voltage range Ve1 is, for example, higher than the second positive peak voltage Vp2.

[0067] Figure 13 corresponds to the magnetic head 112. In the magnetic head 112, the plurality of peaks include a first negative peak n1 and a first positive peak p1. In the first operation OP1, the voltage Va1 is within the first voltage range Ve1. The first voltage range Ve1 is higher than the first positive peak voltage Vp1. In the second operation OP2, the voltage Va1 is within the second voltage range Ve2. The second voltage range Ve2 is lower than, for example, the first negative peak voltage Vn1.

[0068] Figure 14 corresponds to the magnetic head 113. In the magnetic head 113, the plurality of peaks include a first negative peak n1, a first positive peak p1, and a second positive peak p2. In the first operation OP1, the voltage Va1 is within the first voltage range Ve1. The first voltage range Ve1 is higher than, for example, the second positive peak voltage Vp2. In the second operation OP2, the voltage Va1 is within the second voltage range Ve2. The second voltage range Ve2 is lower than, for example, the first negative peak voltage Vn1.

[0069] (Second Embodiment) The second embodiment relates to a magnetic recording device 210. The magnetic recording device 210 includes a magnetic head, a magnetic recording medium 80, an element circuit 20D, and a control unit 75. The magnetic head is configured to record information on the magnetic recording medium 80.

[0070] In the second embodiment, the magnetic head may have, for example, the configuration illustrated in any of FIGS. 7 to 10. The magnetic head includes a first magnetic pole 31, a second magnetic pole 32, and a magnetic element 20 provided between the first magnetic pole 31 and the second magnetic pole 32. The magnetic element 20 includes a first magnetic layer 21 provided between the first magnetic pole 31 and the second magnetic pole 32, a second magnetic layer 22 provided between the first magnetic layer 21 and the second magnetic pole 32, a third magnetic layer 23 provided between the second magnetic layer 22 and the second magnetic pole 32, and a fourth magnetic layer 24 provided between the third magnetic layer 23 and the second magnetic pole 32. The magnetic element 20 may include 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 magnetic element 20 may further include a fifth magnetic layer 25 and a sixth non-magnetic layer 46 (see FIG. 10).

[0071] The element circuit 20D is configured to supply an element current ic between the first magnetic pole 31 and the second magnetic pole 32. The element circuit 20D is configured to perform a first operation OP1 and a second operation OP2. In the first operation OP1, the element current ic flows from the first magnetic pole 31 to the second magnetic pole 32. In the second operation OP2, the element current ic flows from the second magnetic pole 32 to the first magnetic pole 31.

[0072] In the first operation OP1 and the second operation OP2, the characteristics described with respect to FIG. 4 are obtained. In the first operation OP1, although the oscillation intensity SR1 is relatively low at the initial stage of switching, a high oscillation intensity SR1 is obtained after a long time from switching. In the second operation OP2, although a relatively high oscillation intensity SR1 is obtained at the initial stage of switching, the oscillation intensity SR1 is relatively low after a long time from switching. Based on the recording conditions that match such characteristics, the first operation OP1 or the second operation OP2 is switched and performed.

[0073] In the second embodiment, in the magnetic element 20, the first area of the first surface F1 may be the same as the second area of the second surface F2. The first area may be larger than the second area. The first area may be smaller than the second area. In the second embodiment, the operation of the control unit 75 is changed according to the recording conditions.

[0074] FIG. 15 is a flowchart illustrating the operation of the magnetic recording apparatus according to the second embodiment. As shown in FIG. 15, in the magnetic recording apparatus 211 according to the embodiment, the control unit 75 determines whether the recording position on the magnetic recording medium 80 is inside the determined position (step S11). When the recording position on the magnetic recording medium 80 is inside the determined position, the control unit 75 causes the element circuit 20D to perform the first operation OP1 (step S21). When the recording position on the magnetic recording medium 80 is not inside the determined position, the control unit 75 causes the element circuit 20D to perform the second operation OP2 (step S22).

[0075] The magnetic recording medium 80 is disk-shaped. When the recording position is inside, the first operation OP1 is performed. When the recording position is outside, the second operation OP2 is performed. Thereby, recording with a high recording density can be performed at high speed.

[0076] FIG. 16 is a flowchart illustrating the operation of the magnetic recording apparatus according to the second embodiment. As shown in FIG. 16, in the magnetic recording apparatus 212 according to the embodiment, the control unit 75 determines whether the circumferential recording density is lower than a determined density Vd1 (step S12). When the circumferential recording density is lower than the determined density Vd1, the control unit 75 causes the element circuit 20D to perform the first operation OP1 (step S21). When the circumferential recording density is not lower than the determined density Vd1, the control unit 75 causes the element circuit 20D to perform the second operation OP2 (step S22).

[0077] For example, in the case of low BPI (Bits per Inch), the first operation OP1 is performed. For example, when the BPI is high, the second operation OP2 is performed. Thereby, recording with a high recording density can be performed at high speed.

[0078] FIG. 17 is a flowchart illustrating the operation of the magnetic recording apparatus according to the second embodiment. As shown in FIG. 17, in the magnetic recording apparatus 213 according to the embodiment, the control unit 75 determines whether shingled magnetic recording (SMR) is performed (step S13). When the control unit 75 performs shingled magnetic recording, the control unit 75 causes the element circuit 20D to perform the first operation OP1 (step S21). When the control unit 75 performs recording that is not shingled magnetic recording, the control unit 75 causes the element circuit 20D to perform the second operation OP2 (step S22).

[0079] For example, when shingled magnetic recording is performed, the first operation OP1 is performed. For example, when conventional magnetic recording (CMR) is performed, the second operation OP2 is performed. Thereby, recording with a high recording density can be performed at high speed.

[0080] Hereinafter, examples of other configurations of the magnetic recording device according to the embodiment will be described.

[0081] FIG. 18 is a schematic perspective view illustrating a magnetic recording device according to an embodiment. As shown in FIG. 18, a magnetic head (for example, magnetic head 110) according to the embodiment is used together with a magnetic recording medium 80. In this example, the magnetic head 110 includes a recording unit 60 and a reproducing unit 70. Information is recorded on the magnetic recording medium 80 by the recording unit 60 of the magnetic head 110. The information recorded on the magnetic recording medium 80 is reproduced by the reproducing unit 70.

[0082] The magnetic recording medium 80 includes, for example, a medium substrate 82 and a magnetic recording layer 81 provided on the medium substrate 82. The magnetization 83 of the magnetic recording layer 81 is controlled by the recording unit 60.

[0083] The reproducing unit 70 includes, for example, a first reproducing magnetic shield 72a, a second reproducing magnetic shield 72b, and a magnetic reproducing element 71. The magnetic reproducing element 71 is provided between the first reproducing magnetic shield 72a and the second reproducing magnetic shield 72b. The magnetic reproducing element 71 can output a signal corresponding to the magnetization 83 of the magnetic recording layer 81.

[0084] As shown in FIG. 18, the magnetic recording medium 80 moves relative to the magnetic head 110 in the direction of the medium movement direction 85. By the magnetic head 110, information corresponding to the magnetization 83 of the magnetic recording layer 81 is controlled at an arbitrary position. By the magnetic head 110, information corresponding to the magnetization 83 of the magnetic recording layer 81 is reproduced at an arbitrary position.

[0085] FIG. 19 is a schematic perspective view illustrating a part of a magnetic recording device according to an embodiment. FIG. 19 illustrates a head slider. The magnetic head 110 is provided on the head slider 159. The head slider 159 includes, for example, Al2O3 / TiC or the like. The head slider 159 moves relative to the magnetic recording medium while floating or contacting on the magnetic recording medium.

[0086] The head slider 159 has, for example, an air inlet side 159A and an air outlet side 159B. The magnetic head 110 is disposed on the side surface of the air outlet side 159B of the head slider 159. Thus, the magnetic head 110 moves relative to the magnetic recording medium while floating or contacting on the magnetic recording medium.

[0087] FIG. 20 is a schematic perspective view illustrating a magnetic recording apparatus according to an embodiment. FIGS. 21(a) and 21(b) are schematic perspective views illustrating a part of a magnetic recording apparatus according to an embodiment. As shown in FIG. 20, in the magnetic recording apparatus 150 according to the embodiment, a rotary actuator is used. The recording medium disk 180 is mounted on the 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 device control unit. The magnetic recording apparatus 150 according to the present embodiment may include a plurality of recording medium disks 180. The magnetic recording apparatus 150 may 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 a flash memory is used for the recording medium 181. For example, the magnetic recording apparatus 150 may be a hybrid HDD (Hard Disk Drive).

[0088] The head slider 159 records and reproduces information to be recorded on the recording medium disk 180. The head slider 159 is provided at the tip of the thin-film suspension 154. A magnetic head according to the embodiment is provided near the tip of the head slider 159.

[0089] When the recording medium disk 180 rotates, the pressing pressure by the suspension 154 and the pressure generated on the medium facing surface (ABS) of the head slider 159 are balanced. The distance between the medium facing surface of the head slider 159 and the surface of the recording medium disk 180 becomes a predetermined flying height. In an embodiment, the head slider 159 may be in contact with the recording medium disk 180. For example, a contact running type may be applied.

[0090] The suspension 154 is connected to one end of the arm 155 (for example, an actuator arm). The arm 155 has, for example, a bobbin portion or the like. The bobbin portion 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 kind 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 portion 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. The magnetic head is provided at one end of the suspension 154. The arm 155 is connected to the other end of the suspension 154.

[0091] The arm 155 is held by ball bearings. The ball bearings are provided at two locations above and below the bearing portion 157. The arm 155 can be rotated and slid by the voice coil motor 156. The magnetic head can be moved to any position on the recording medium disk 180.

[0092] FIG. 21(a) illustrates a partial configuration of the magnetic recording apparatus and is an enlarged perspective view of the head stack assembly 160. FIG. 21(b) is a perspective view illustrating a magnetic head assembly (head gimbal assembly: HGA) 158 that is part of the head stack assembly 160.

[0093] As shown in FIG. 21(a), the head stack assembly 160 includes a bearing portion 157, a head gimbal assembly 158, and a support frame 161. The head gimbal assembly 158 extends from the bearing portion 157. The support frame 161 extends from the bearing portion 157. The extending direction of the support frame 161 is opposite to the extending direction of the head gimbal assembly 158. The support frame 161 supports the coil 162 of the voice coil motor 156.

[0094] As shown in FIG. 21(b), the head gimbal assembly 158 has an arm 155 extending from the bearing portion 157 and a suspension 154 extending from the arm 155.

[0095] 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.

[0096] The magnetic head assembly (head gimbal assembly) 158 according to the embodiment includes the magnetic head according to the embodiment, the head slider 159 provided with the magnetic head, the suspension 154, and the 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.

[0097] The suspension 154 has, for example, a lead wire (not shown) for signal recording and reproduction. The suspension 154 may have, for example, a lead wire (not shown) for a heater for floating height adjustment. The suspension 154 may have a lead wire (not shown) for an oscillation element or the like. These lead wires and a plurality of electrodes provided on the magnetic head are electrically connected.

[0098] In the magnetic recording device 150, a signal processing unit 190 is provided. The signal processing unit 190 records and reproduces signals on and from a magnetic recording medium using a magnetic head. The input / output lines of the signal processing unit 190 are connected to, for example, the electrode pads of the head gimbal assembly 158 and are electrically connected to the magnetic head.

[0099] The magnetic recording device 150 according to the embodiment includes a magnetic recording medium, a magnetic head according to the embodiment, a movable part, a position control part, and a signal processing part. The movable part enables relative movement between the magnetic recording medium and the magnetic head in a state where they are separated or in contact with each other. The position control part aligns the magnetic head with a predetermined recording position on the magnetic recording medium. The signal processing part records and reproduces signals on and from the magnetic recording medium using the magnetic head.

[0100] For example, as the magnetic recording medium described above, a recording medium disk 180 is used. The movable part described above includes, for example, a head slider 159. The position control part described above includes, for example, a head gimbal assembly 158.

[0101] The embodiment may include the following configuration technical solutions. (Technical solution 1) A first magnetic pole, A second magnetic pole, A magnetic element provided between the first magnetic pole and the second magnetic pole in a first direction from the first magnetic pole to the second magnetic pole, and the magnetic element includes a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, and the first magnetic layer includes a first surface facing the first magnetic pole, the fourth magnetic layer includes a second surface facing the second magnetic pole, A magnetic head in which a first area of the first surface is larger than a second area of the second surface.

[0102] (Technical Solution 2) The first magnetic pole includes a medium facing surface, A first length along a second direction of the first surface is longer than a second length along the second direction of the second surface, The second direction is along the medium facing surface and orthogonal to the first direction, and the magnetic head according to Technical Solution 1.

[0103] (Technical Solution 3) The first surface includes a first end and a first other end, The direction from the first other end to the first end is along the second direction, The second surface includes a second end and a second other end, The direction from the second other end to the second end is along the second direction, The distance between the first end and the second end is shorter than the distance between the first end and the second other end, A first angle between a first straight line passing through the first end and the second end and a direction perpendicular to the first surface is 5 degrees or more and 15 degrees or less, and the magnetic head according to Technical Solution 2.

[0104] (Technical Solution 4) A second angle between a second straight line passing through the first other end and the second other end and the direction perpendicular to the first surface is 5 degrees or more and 15 degrees or less, and the magnetic head according to Technical Solution 3.

[0105] (Technical Solution 5) The magnetic element is A first non-magnetic layer provided between the first magnetic pole and the first magnetic layer, A second non-magnetic layer provided between the first magnetic layer and the second magnetic layer, A third non-magnetic layer provided between the second magnetic layer and the third magnetic layer, A fourth non-magnetic layer provided between the third magnetic layer and the fourth magnetic layer, A fifth non-magnetic layer provided between the fourth magnetic layer and the second magnetic pole, The magnetic head according to any one of Technical Solutions 1 to 4, further comprising

[0106] (Technical Solution 6) The first non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The second non-magnetic layer contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, The third non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The fourth non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The fifth non-magnetic layer contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, the magnetic head according to Technical Solution 5.

[0107] (Technical Solution 7) The first thickness of the first magnetic layer along the first direction is greater than the second thickness of the second magnetic layer along the first direction, The third thickness of the third magnetic layer along the first direction is greater than the fourth thickness of the fourth magnetic layer along the first direction, the magnetic head according to Technical Solution 6.

[0108] (Technical Solution 8) The first non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The second non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The third non-magnetic layer contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, The fourth non-magnetic layer contains at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The fifth non-magnetic layer contains at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, the magnetic head according to Technical Solution 5.

[0109] (Technical solution 9) The first thickness of the first magnetic layer along the first direction is greater than the second thickness of the second magnetic layer along the first direction, The magnetic head according to Technical solution 8, wherein the third thickness of the third magnetic layer along the first direction is greater than the fourth thickness of the fourth magnetic layer along the first direction.

[0110] (Technical solution 10) The first non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The second non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The third non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, The fourth non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The magnetic head according to Technical solution 5, wherein the fifth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W.

[0111] (Technical solution 11) The first thickness of the first magnetic layer along the first direction is greater than the second thickness of the second magnetic layer along the first direction, The magnetic head according to Technical solution 10, wherein the third thickness of the third magnetic layer along the first direction is less than the fourth thickness of the fourth magnetic layer along the first direction.

[0112] (Technical solution 12) The first non-magnetic layer is in contact with the first magnetic pole and the first magnetic layer, The second non-magnetic layer is in contact with the first magnetic layer and the second magnetic layer, The third non-magnetic layer is in contact with the second magnetic layer and the third magnetic layer, The fourth non-magnetic layer is in contact with the third magnetic layer and the fourth magnetic layer, The fifth non-magnetic layer is in contact with the fourth magnetic layer and the second magnetic pole, and is the magnetic head according to any one of Technical Solutions 5 to 11.

[0113] (Technical Solution 13) The magnetic element a fifth magnetic layer provided between the third non-magnetic layer and the third magnetic layer, a sixth non-magnetic layer provided between the fifth magnetic layer and the third magnetic layer, and further includes the magnetic head according to Technical Solution 5.

[0114] (Technical Solution 14) The first non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The second non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The third non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, The fourth non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, The fifth non-magnetic layer includes at least one selected from the group consisting of Ru, Ir, Ta, Rh, Pd, Pt, and W, The sixth non-magnetic layer includes at least one selected from the group consisting of Cu, Au, Cr, V, Al, and Ag, and is the magnetic head according to Technical Solution 13.

[0115] (Technical Solution 15) The first thickness of the first magnetic layer along the first direction is greater than the second thickness of the second magnetic layer along the first direction, The third thickness of the third magnetic layer along the first direction is greater than the fourth thickness of the fourth magnetic layer along the first direction, The fifth thickness of the fifth magnetic layer along the first direction is less than the third thickness, and is the magnetic head according to Technical Solution 14.

[0116] (Technical Solution 16) The first operation and the second operation are performed, In the first operation, the element current supplied between the first magnetic pole and the second magnetic pole flows from the first magnetic pole to the second magnetic pole. In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. The magnetic head according to any one of Technical Solutions 1 to 15.

[0117] (Technical Solution 17) A magnetic head according to any one of Technical Solutions 1 to 15, An element circuit configured to supply an element current between the first magnetic pole and the second magnetic pole, comprising The element circuit is configured to perform a first operation and a second operation. In the first operation, the element current flows from the first magnetic pole to the second magnetic pole. In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. A magnetic recording device.

[0118] (Technical Solution 18) A magnetic head, a magnetic recording medium, an element circuit, a control unit, comprising The magnetic head is configured to record information on the magnetic recording medium. The magnetic head a first magnetic pole, a second magnetic pole, a magnetic element provided between the first magnetic pole and the second magnetic pole, including The magnetic element a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, including The element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole. The element circuit is configured to perform a first operation and a second operation. In the first operation, the element current flows from the first magnetic pole to the second magnetic pole. In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. When the recording position on the magnetic recording medium is inside the determined position, the control unit is configured to cause the element circuit to perform the first operation. A magnetic recording apparatus, wherein when the recording position on the magnetic recording medium is not inside the determined position, the control unit is configured to cause the element circuit to perform the second operation.

[0119] (Technical Proposal 19) A magnetic head, A magnetic recording medium, An element circuit, A control unit, and includes: The magnetic head is configured to record information on the magnetic recording medium. The magnetic head includes a first magnetic pole, a second magnetic pole, and a magnetic element provided between the first magnetic pole and the second magnetic pole. and includes: The magnetic element includes a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, and a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole. and includes: The element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole. The element circuit is configured to perform a first operation and a second operation. In the first operation, the element current flows from the first magnetic pole to the second magnetic pole. In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. The control unit is configured to cause the element circuit to perform the first operation when the circumferential recording density is lower than a determined density. The control unit is configured to cause the element circuit to perform the second operation when the circumferential recording density is not lower than the determined density, a magnetic recording device.

[0120] (Technical Proposal 20) A magnetic head, A magnetic recording medium, An element circuit, A control unit, Comprising, The magnetic head is configured to record information on the magnetic recording medium. The magnetic head, A first magnetic pole, A second magnetic pole, A magnetic element provided between the first magnetic pole and the second magnetic pole, Including, The magnetic element, A first magnetic layer provided between the first magnetic pole and the second magnetic pole, A second magnetic layer provided between the first magnetic layer and the second magnetic pole, A third magnetic layer provided between the second magnetic layer and the second magnetic pole, A fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, Including, The element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole. The element circuit is configured to perform a first operation and a second operation. In the first operation, the element current flows from the first magnetic pole to the second magnetic pole. In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. When the control unit performs the overwriting recording, it is configured to cause the element circuit to perform the first operation. The magnetic recording device, wherein the control unit is configured to cause the element circuit to perform the second operation when performing a recording other than the overwriting recording.

[0121] According to the embodiment, a magnetic recording device capable of improving the recording density can be provided.

[0122] In the present specification, "vertical" and "parallel" include not only strict vertical and strict parallel, but also, for example, variations in the manufacturing process, etc., and may be substantially vertical and substantially parallel.

[0123] As described above, the embodiments of the present invention have been described with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific configurations of each element such as magnetic poles, magnetic elements, magnetic layers, non-magnetic layers, and control units included in the magnetic head and the magnetic recording device, those skilled in the art can appropriately select from the known range to implement the present invention in the same manner, and as long as the same effects can be obtained, it is included in the scope of the present invention.

[0124] Combinations of any two or more elements of each specific example within a technically possible range are also included in the scope of the present invention as long as they include the gist of the present invention.

[0125] In addition, based on the magnetic recording device described above as an embodiment of the present invention, all magnetic recording devices that can be appropriately designed and modified by those skilled in the art also belong to the scope of the present invention as long as they include the gist of the present invention.

[0126] In addition, within the scope of the idea of the present invention, those skilled in the art can conceive various modification examples and correction examples, and it is understood that those modification examples and correction examples also belong to the scope of the present invention.

[0127] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Signs

[0128] 20: Magnetic element, 20D: Element circuit, 21 - 25: First - fifth magnetic layers, 21a, 24a: First, second ends, 21b, 24b: First, second other ends, 30D: Recording circuit, 30F: Medium - facing surface, 30c: Coil, 30i: Insulating part, 31, 32: First, second magnetic poles, 33: Shield, 41 - 46: First - sixth non - magnetic layers, 60: Recording part, 70: Reproducing part, 71: Magnetic reproducing element, 72a, 72b: First, second reproducing magnetic shields, 75: Control part, 80: Magnetic recording medium, 81: Magnetic recording layer, 82: Medium substrate, 83: Magnetization, 85: Medium moving direction, 110 - 113: Magnetic heads, 150: Magnetic recording apparatus, 154: Suspension, 155: Arm, 156: Voice coil motor, 157: Bearing part, 158: Head gimbal assembly, 159: Head slider, 159A: Air - inflow side, 159B: Air - outflow side, 160: Head stack assembly, 161: Support frame, 162: Coil, 180: Recording medium disk, 180M: Spindle motor, 181: Recording medium, 190: Signal processing part, 210 - 213: Magnetic recording apparatuses, AR: Arrow, CF1 - CF4: First - fourth configurations, D1, D2: First, second directions, F1, F2: First, second surfaces, Hg: Gap magnetic field, Iw: Recording current, Ln1, Ln2: First, second straight lines, OP1, OP2: First, second operations, Rd1: Differential electric resistance, SR1: Oscillation intensity, T1, T2: First, second terminals, Tc1, Tc2: First, second coil terminals, Va1: Voltage, Ve1, Ve2: First, second voltage ranges, Vn1: First negative peak voltage, Vp1, Vp2: First, second positive peak voltages, W1, W2: First, second wirings, ic: Element current, je: Electron flow, n1: First negative peak, p1, p2: First, second positive peaks, t21 - t25: First - fifth thicknesses, t41 - t46: Thicknesses, tm: Time, θ1, θ2: First, second angles

Claims

1. a first magnetic pole, a second magnetic pole, a magnetic element provided between the first magnetic pole and the second magnetic pole in a first direction from the first magnetic pole to the second magnetic pole, comprising, wherein the magnetic element comprises a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, including, wherein the first magnetic layer includes a first surface facing the first magnetic pole, the fourth magnetic layer includes a second surface facing the second magnetic pole, and a magnetic head in which a first area of the first surface is larger than a second area of the second surface.

2. wherein the first magnetic pole includes a medium-facing surface, a first length along a second direction of the first surface is longer than a second length along the second direction of the second surface, and the second direction is along the medium-facing surface and perpendicular to the first direction, the magnetic head according to claim 1.

3. wherein the first surface includes a first end and a first other end, a direction from the first other end to the first end is along the second direction, the second surface includes a second end and a second other end, a direction from the second other end to the second end is along the second direction, a distance between the first end and the second end is shorter than a distance between the first end and the second other end, and a first angle between a first straight line passing through the first end and the second end and a direction perpendicular to the first surface is 5 degrees or more and 15 degrees or less, the magnetic head according to claim 2.

4. wherein the magnetic element further includes a first non-magnetic layer provided between the first magnetic pole and the first magnetic layer, a second non-magnetic layer provided between the first magnetic layer and the second magnetic layer, a third non-magnetic layer provided between the second magnetic layer and the third magnetic layer, a fourth non-magnetic layer provided between the third magnetic layer and the fourth magnetic layer, and a fifth non-magnetic layer provided between the fourth magnetic layer and the second magnetic pole, the magnetic head according to claim 1.

5. wherein the magnetic element further includes a fifth magnetic layer provided between the third non-magnetic layer and the third magnetic layer, and a sixth non-magnetic layer provided between the fifth magnetic layer and the third magnetic layer, the magnetic head according to claim 4.

6. a first operation and a second operation are performed, in the first operation, an element current supplied between the first magnetic pole and the second magnetic pole flows from the first magnetic pole to the second magnetic pole, In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. The magnetic head according to any one of claims 1 to 5.

7. The magnetic head according to claim 1, and an element circuit configured to supply an element current between the first magnetic pole and the second magnetic pole, comprising: The element circuit is configured to perform a first operation and a second operation, In the first operation, the element current flows from the first magnetic pole to the second magnetic pole, In the second operation, the element current flows from the second magnetic pole to the first magnetic pole. A magnetic recording device.

8. A magnetic head, a magnetic recording medium, an element circuit, a control unit, comprising: The magnetic head is configured to record information on the magnetic recording medium, The magnetic head has a first magnetic pole, a second magnetic pole, and a magnetic element provided between the first magnetic pole and the second magnetic pole, including: The magnetic element has a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, and a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, including: The element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole, The element circuit is configured to perform a first operation and a second operation, In the first operation, the element current flows from the first magnetic pole to the second magnetic pole, In the second operation, the element current flows from the second magnetic pole to the first magnetic pole, The control unit is configured to cause the element circuit to perform the first operation when the recording position on the magnetic recording medium is inside the determined position, The control unit is configured to cause the element circuit to perform the second operation when the recording position on the magnetic recording medium is not inside the determined position. A magnetic recording device.

9. A magnetic head, a magnetic recording medium, an element circuit, a control unit, comprising: The magnetic head is configured to record information on the magnetic recording medium, The magnetic head has a first magnetic pole, a second magnetic pole, and a magnetic element provided between the first magnetic pole and the second magnetic pole, including: The magnetic element has a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, A third magnetic layer provided between the second magnetic layer and the second magnetic pole, a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, comprising, the element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole, the element circuit is configured to perform a first operation and a second operation, in the first operation, the element current flows from the first magnetic pole to the second magnetic pole, in the second operation, the element current flows from the second magnetic pole to the first magnetic pole, the control unit is configured to cause the element circuit to perform the first operation when the circumferential recording density is lower than a determined density, the control unit is configured to cause the element circuit to perform the second operation when the circumferential recording density is not lower than the determined density, a magnetic recording device.

10. A magnetic head, a magnetic recording medium, an element circuit, a control unit, comprising, the magnetic head is configured to record information on the magnetic recording medium, the magnetic head, a first magnetic pole, a second magnetic pole, a magnetic element provided between the first magnetic pole and the second magnetic pole, comprising, the magnetic element, a first magnetic layer provided between the first magnetic pole and the second magnetic pole, a second magnetic layer provided between the first magnetic layer and the second magnetic pole, a third magnetic layer provided between the second magnetic layer and the second magnetic pole, a fourth magnetic layer provided between the third magnetic layer and the second magnetic pole, comprising, the element circuit is configured to supply an element current between the first magnetic pole and the second magnetic pole, the element circuit is configured to perform a first operation and a second operation, in the first operation, the element current flows from the first magnetic pole to the second magnetic pole, in the second operation, the element current flows from the second magnetic pole to the first magnetic pole, the control unit is configured to cause the element circuit to perform the first operation when performing overwriting recording, the control unit is configured to cause the element circuit to perform the second operation when performing recording other than overwriting recording, a magnetic recording device.

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