Magnetic disk device

Abstract

A magnetic disk device suppresses fluctuation of auxiliary effect caused by fluctuation of size of a main pole of each head. An embodiment relates to a magnetic disk device including: a head including a main pole, an auxiliary pole, a side shield, a high-frequency oscillation element, and a magnetic flux control element, the auxiliary pole being disposed apart from the main pole by a write gap, and constituting a magnetic circuit together with the main pole, the side shield being disposed apart from the main pole by a side gap in both sides in a track width direction of the main pole, the high-frequency oscillation element being disposed between the main pole and the auxiliary pole, the magnetic flux control element being disposed between the main pole and the side shield, and controlling an oscillation frequency of the high-frequency oscillation element; an oscillation element control section controlling a bias current supplied to the high-frequency oscillation element; and a magnetic flux control element control section controlling a bias current supplied to the magnetic flux control element.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2022-151048 (filed on September 22, 2022). This application incorporates the entire contents of the basic application by reference to that basic application. Technical Field

[0002] Embodiments of the present invention relate to disk drives. Background Technology

[0003] To increase the recording density of hard disk drives (HDDs), disk devices using auxiliary recording methods have been proposed. Examples of auxiliary recording methods include high-frequency assisted magnetic recording, which uses a high-frequency oscillation element as an auxiliary component.

[0004] The following problem exists in disk devices with multiple heads: due to the size fluctuation of the main magnetic pole of each head, the magnetic field strength applied to the writing gap of the high-frequency oscillation element will fluctuate. As a result, the oscillation frequency of the high-frequency oscillation element will change, resulting in a mismatch between the oscillation frequency and the resonant frequency of the medium, and the auxiliary effect will be weakened or disappear. Summary of the Invention

[0005] The embodiments of the present invention suppress fluctuations in the auxiliary effect caused by dimensional fluctuations of the main magnetic poles of each head in a disk device with an auxiliary recording method.

[0006] According to an embodiment, a disk drive is provided, comprising: a read / write head having a main magnetic pole, an auxiliary magnetic pole, a side shield, a high-frequency oscillation element, and a flux control element; the auxiliary magnetic pole being disposed with an open write gap from the main magnetic pole, forming a magnetic circuit together with the main magnetic pole; the side shield being disposed with an open side gap on both sides of the main magnetic pole in the track width direction; the high-frequency oscillation element being disposed between the main magnetic pole and the auxiliary magnetic pole in the write gap; and the flux control element being disposed between the main magnetic pole and the side shield in the side gap, controlling the oscillation frequency of the high-frequency oscillation element; an oscillation element control unit controlling the bias current supplied to the high-frequency oscillation element; and a flux control element control unit controlling the bias current supplied to the flux control element. Attached Figure Description

[0007] Figure 1 This is a block diagram that schematically illustrates the disk device involved in the implementation.

[0008] Figure 2 This is a side view showing the read / write head and disk in a floating state.

[0009] Figure 3 It is a cross-sectional view that is enlarged and roughly represented by the head of the read / write head and a part of the disk.

[0010] Figure 4 This is a diagram obtained by viewing the recording head in the magnetic head used in the embodiment from the air support side.

[0011] Figure 5 It means Figure 4 A diagram showing the configuration of the magnetic head and the magnetic recording medium.

[0012] Figure 6 This is a diagram showing the flow of magnetic flux in the head when no drive current is supplied to the FCL.

[0013] Figure 7 This is a diagram showing the flow of magnetic flux in the head when a drive current is applied to the FCL.

[0014] Figure 8 This is observed from a cross-section along the center of the track. Figure 6 The diagram is obtained by observing the flow of magnetic flux through the magnetic head.

[0015] Figure 9 This is observed from a cross-section along the center of the track. Figure 7 The diagram is obtained by observing the flow of magnetic flux through the magnetic head.

[0016] Figure 10 This is a schematic diagram showing the cross-sectional configuration of the read / write head used in the disk device according to Embodiment 1.

[0017] Figure 11 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in Example 1.

[0018] Figure 12 This is a graph showing the relationship between the width PWA of the head main magnetic pole and the STO oscillation frequency when If is not applied.

[0019] Figure 13 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in an example of the disk device of Embodiment 2.

[0020] Figure 14 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in another example of the disk device of Embodiment 2.

[0021] Figure 15 This is a graph showing the optimal relationship between If and PWA when the oscillation frequency is adjusted to 24GHz.

[0022] Explanation of reference numerals in the attached figures

[0023] 10 Disk drive; 13 Air support surface; 16 Magnetic head; 52, 52a Insulating layer; 60 Main magnetic pole; 62 Auxiliary magnetic pole; 65 High-frequency oscillation element; 65a Third non-magnetic conductive layer; 65b Spin injection layer; 65c Fourth non-magnetic conductive layer; 65d Oscillation layer; 65e Fifth non-magnetic conductive layer; 82 Oscillation element control unit; 85 Flux control element control unit; 111 Flux control element; 111a First non-magnetic conductive layer; 111b Magnetization reversal layer; 111c Second non-magnetic conductive layer; 112 Side shielding. Detailed Implementation

[0024] The disk device involved in the implementation includes: a magnetic head having a main magnetic pole, an auxiliary magnetic pole, a side shield, a high-frequency oscillation element, and a flux control element; the auxiliary magnetic pole is disposed with an open write gap to the main magnetic pole and together with the main magnetic pole forms a magnetic circuit; the side shield is disposed with an open side gap on both sides in the track width direction of the main magnetic pole; the high-frequency oscillation element is disposed in the write gap; the flux control element is disposed in the side gap and controls the oscillation frequency of the high-frequency oscillation element; an oscillation element control unit controls the bias current supplied to the high-frequency oscillation element; and a flux control element control unit controls the bias current supplied to the flux control element.

[0025] According to an embodiment, in a high-frequency assisted magnetic recording head that has a high-frequency oscillation element in the write gap between the main magnetic pole and the auxiliary magnetic pole, a flux control element is also provided between the main magnetic pole and the side shield. In a disk drive equipped with this head, an oscillation element control unit and a flux control element control unit are provided. When using such a disk drive, by adjusting the magnetization state of the flux control element using the flux control element control unit, the magnetic field strength of the external magnetic field applied within the write gap of the high-frequency oscillation element can be adjusted, thereby adjusting the oscillation frequency of the high-frequency oscillation element. Therefore, even when a deviation occurs between the media resonant frequency and the oscillation frequency of the high-frequency oscillation element of each head due to fluctuations in the size of the head's main magnetic pole, the flux control element can be driven to independently adjust the oscillation frequency of each head to match the media resonant frequency. According to the embodiment, by using the flux control element to adjust the oscillation frequency of the high-frequency element, fluctuations in the auxiliary effect caused by fluctuations in the size of the head's main magnetic pole can be suppressed.

[0026] The flux control element may, for example, have a first non-magnetic conductive layer, a magnetization reversal layer, and a second non-magnetic conductive layer stacked sequentially from the main magnetic pole side.

[0027] Materials used as the first non-magnetic conductive layer include, for example, Ta, Ir, Ru, NiCr, and W.

[0028] Materials used as magnetization reversal layers include, for example, alloys such as NiFe, FeCo, FeCr, and FeV.

[0029] Materials used as the second non-magnetic conductive layer include, for example, Cu and Ru.

[0030] Alternatively, the order in which the first non-magnetic conductive layer, the magnetization reversal layer, and the second non-magnetic conductive layer are stacked on the main magnetic pole can be reversed.

[0031] A flux control element can be installed between the main magnetic pole and the side shields located on both sides of the main magnetic pole. The two flux control elements can have the same configuration.

[0032] In addition, the high-frequency oscillation element may have a third non-magnetic conductive layer, a spin injection layer, a fourth non-magnetic conductive layer, an oscillation layer, and a fifth non-magnetic conductive layer stacked sequentially from the main magnetic pole side.

[0033] Materials used as the third non-magnetic conductive layer include, for example, Ta, Ir, Ru, NiCr, and W.

[0034] Materials used as the spin-injection layer can include alloys such as NiFe, FeCo, FeCr, and FeV.

[0035] Materials used as the fourth non-magnetic conductive layer include, for example, Cu, Ru, etc.

[0036] Materials used as the oscillation layer can include alloys such as NiFe, FeCo, FeCr, and FeV.

[0037] Materials used as the fifth non-magnetic conductive layer include, for example, Ta, Ir, Ru, NiCr, and W.

[0038] The order in which the third non-magnetic conductive layer, the spin-injection layer, the fourth non-magnetic conductive layer, the oscillation layer, and the fifth non-magnetic conductive layer are stacked on the main magnetic pole can be reversed.

[0039] The disk drive may have two or more heads, including: a first head having a first main magnetic pole with a first width in the track width direction and subjected to a first bias current; and a second head having a second main magnetic pole with a second width in the track width direction that is larger than the first width and subjected to a second bias current that is lower than the first bias current. Therefore, the larger the physical width of the air support surface at the tail end of the main magnetic pole, the lower the current flowing through the main magnetic pole, and the better the fluctuation of auxiliary effects caused by head size variations can be suppressed.

[0040] The oscillation element control unit and the flux control element control unit can be set up independently of each other.

[0041] The embodiments will now be described with reference to the accompanying drawings.

[0042] Furthermore, the disclosure is merely an example, and technical solutions that can be readily conceived by those skilled in the art with appropriate modifications to the inventive spirit are naturally included within the scope of this invention. Additionally, sometimes, to make the explanation clearer, the drawings schematically represent the width, thickness, shape, etc., of various parts compared to the actual technical solution; however, this is merely an example and does not limit the interpretation of the invention. Furthermore, in this specification and the drawings, sometimes the same reference numerals are used for elements that have been described with respect to the preceding drawings, and detailed descriptions are appropriately omitted.

[0043] Figure 1 This is a block diagram that schematically represents a hard disk drive (HDD) as an embodiment of the disk device. Figure 2 This is a side view showing the read / write head and disk in the floating state. Figure 3 It is a cross-sectional view that is enlarged and roughly represented by the head of the read / write head and a part of the disk.

[0044] like Figure 1 As shown, the HDD 10 includes a rectangular housing 11, a disk 12 serving as a recording medium disposed within the housing 11, a spindle motor 14 supporting and rotating the disk 12, and multiple read / write heads 16 for writing and reading data from the disk 12. Furthermore, the HDD 10 includes a head actuator 18 that moves and positions the read / write heads 16 onto any track on the disk 12. The head actuator 18 includes a suspension assembly 20 that movably supports the read / write heads 16, and a voice coil motor (VCM) 22 that rotates the suspension assembly 20.

[0045] HDD10 includes a head amplifier IC30, a main controller IC40, and a driver IC48. The head amplifier IC30 is disposed, for example, in the suspension assembly 20 and electrically connected to the read / write head 16. The main controller IC40 and driver IC48 are configured, for example, as a control circuit board (not shown) disposed on the rear side of the housing 11. The main controller 40 includes an R / W channel (RDC) 42, a hard disk controller (HDC) 44, and a microprocessor (MPU) 46. The main controller 40 is electrically connected to the head amplifier IC30 and, via the driver IC48, is electrically connected to the VCM 22 and the spindle motor 14. HDD10 can be connected to a host computer (not shown).

[0046] like Figure 1 and Figure 2As shown, the disk 12 is a vertical magnetic recording medium having a recording layer that is anisotropic in a direction perpendicular to the disk surface. Specifically, the disk 12 has, for example, a substrate 101, which is formed into a circular plate with a diameter of approximately 2.5 inches (6.35 cm) and is made of a non-magnetic material. A soft magnetic layer 102 as a base layer, a magnetic recording layer 103 on top of the substrate 101, and a protective film 104 are sequentially stacked on each surface of the substrate 101. The disk 12 is coaxially fitted into the hub of the spindle motor 14. The disk 12 is rotated at a predetermined speed in the direction of arrow B by the spindle motor 14.

[0047] The suspension assembly 20 has a bearing portion 24 that is rotatably fixed to the housing 11, and a plurality of suspension elements 26 extending from the bearing portion 24. For example... Figure 2 As shown, the magnetic head 16 is supported on the extended ends of each suspension 26. The magnetic head 16 is electrically connected to the head amplifier IC 30 via a wiring component 28 provided on the suspension assembly 20.

[0048] Next, the structure of the magnetic head 16 will be described in detail.

[0049] like Figure 2 and Figure 3 As shown, the magnetic head 16 is configured as a floating head, having a slider 15 formed in a generally rectangular parallelepiped shape and a head 17 formed at the end of the slider 15 on the outflow end (tail) side. The slider 15 is formed, for example, from a sintered body of aluminum and titanium carbide (AlTiC), and the head 17 is made of a multilayer thin film.

[0050] The slider 15 has a rectangular ABS (air support surface) 13 opposite to the surface of the disk 12. The slider 15 is maintained at a predetermined position above the surface of the disk 12 by the airflow C generated between the disk surface and the ABS 13 due to the rotation of the disk 12. The direction of the airflow C is consistent with the rotation direction B of the disk 12. The slider 15 has a leading end 15a on the inflow side of the airflow C and a trailing end 15b on the outflow side of the airflow C.

[0051] like Figure 3As shown, the head 17 is a separate magnetic head, consisting of a playback head 54 and a recording head 58, formed on the trailing end 15b of the slider 15 using a thin-film process. To control the recording and playback float of the head 17, a recording heater 19a is disposed inside the recording head 58, and a playback heater 19b is disposed inside the playback head 54. The playback head 54 consists of a playback element 55, an upper shield 56, and a lower shield 57. The playback element 55 is a magnetic film exhibiting a magnetoresistive effect. The upper shield 56 and lower shield 57 are configured to sandwich the playback element 55, which is implemented using a magnetic film, between the trailing side and the leading side of the playback element 55. The lower ends of these playback elements 55, the upper shield 56, and the lower shield 57 are exposed at the ABS 13 of the slider 15. The playback head 54 is connected to the head amplifier IC 30 via electrodes (not shown), wiring, and wiring components 28, and outputs the read data to the head amplifier IC 30.

[0052] The recording head 58 is positioned relative to the playback head 54 on the trailing end 15b side of the slider 15. The recording head 58 has a main magnetic pole 60 formed of a highly permeable material that generates a recording magnetic field perpendicular to the surface of the disk 12; a return magnetic pole 62 that serves as a return magnetic pole (write shield, first shield); and a leader core 64 that serves as a leader shield (second shield). The main magnetic pole 60 and the return magnetic pole 62 constitute a first magnetic core forming a magnetic circuit, and the main magnetic pole 60 and the leader core 64 constitute a second magnetic core forming a magnetic circuit. The recording head 58 has a first coil (recording coil) 70 wound around the first magnetic core and a second coil (recording coil) 72 wound around the second magnetic core.

[0053] like Figure 3 As shown, the main magnetic pole 60 extends approximately perpendicularly to the surface of the disk 12. The top end 60a of the main magnetic pole 60 on the disk 12 side tapers towards the disk surface, for example, with a trapezoidal cross-section. The top end face of the main magnetic pole 60 is exposed at the ABS13 of the slider 15. The width of the trailing end face 60b of the top end 60a approximately corresponds to the width of the track in the disk 12.

[0054] A return magnetic pole 62, formed of a soft magnetic material, is disposed on the trailing side of the main magnetic pole 60, and is provided to efficiently close the magnetic circuit across the soft magnetic layer 102 of the disk 12 directly below the main magnetic pole 60. The return magnetic pole 62 is formed in a generally L-shape and has a first connection portion 50 connected to the main magnetic pole 60. The first connection portion 50 is connected via a non-conductive material 52 to the upper part of the main magnetic pole 60, that is, the part of the main magnetic pole 60 that has separated from the ABS13.

[0055] The top portion 62a of the return magnetic pole 62 is formed into an elongated rectangular shape, with its top surface exposed in the ABS13 of the slider 15. The leading side end face 62b of the top portion 62a extends along the width direction of the track of the disk 12, and extends approximately perpendicularly to the ABS13. This leading side end face 62b is positioned approximately parallel to the trailing side end face 60b of the main magnetic pole 60, opening the write gap WG.

[0056] The first coil 70 is configured to be wound in a magnetic circuit (first magnetic core) including the main magnetic pole 60 and the return magnetic pole 62. The first coil 70 is wound, for example, around the first connection portion 50. When a signal is written to the disk 12, the first coil 70 excites the main magnetic pole 60 by causing a recording current to flow in the first coil 70, thereby causing magnetic flux to flow in the main magnetic pole 60.

[0057] A spin torque control element (STO) 65 is disposed within the write gap WG between the top end 60a of the main magnetic pole 60 and the return magnetic pole 62, with a portion of it exposed in the ABS13. The lower end face of the STO 65 is not limited to being located in a position coplanar with the ABS13, but may also be located away from the ABS13 in the height direction. Furthermore, the STO is an example of an auxiliary element, for example, it can be configured to provide an auxiliary effect accompanying flux control, or it can be configured to provide a high-frequency auxiliary effect (high-frequency auxiliary element). The flux control is achieved by using spin torque to reverse the magnetization to the opposite direction of the flux in the write gap, and the high-frequency auxiliary effect is achieved by using spin torque to cause high-frequency oscillation of the magnetization to induce resonance of the medium magnetization.

[0058] like Figure 3 As shown, connection terminals 91 and 92 are connected to the main magnetic pole 60 and the return magnetic pole 62, respectively. These connection terminals 91 and 92 are connected to the head amplifier IC30 via wiring. Thus, the current circuit is configured to allow current to flow from the head amplifier IC30 through the main magnetic pole 60, STO65, and return magnetic pole 62 in series. Additionally, connection terminals 97 and 98 are connected to the recording heater 19a and the playback heater 19b, respectively. These connection terminals 97 and 98 are connected to the head amplifier IC30 via wiring.

[0059] like Figure 3 As shown, a leader core 64, formed of a soft magnetic material, is disposed opposite to the main magnetic pole 60 on the leader side of the main magnetic pole 60. The leader core 64 is formed in a generally L-shape, and the top end portion 64a on the disk 12 side is formed in an elongated rectangular shape. The top surface (lower end surface) of this top end portion 64a is exposed in the ABS13 of the slider 15. The trailing end face 64b of the top end portion 64a extends along the width direction of the track of the disk 12. This trailing end face 64b is openly opposed to the leader end face of the main magnetic pole 60. This gap is covered by a protective insulating film 76, which is a non-magnetic material.

[0060] The leader core 64 has a second connection portion 68 that engages with the rear gap between itself and the main magnetic pole 60 at a position where it exits the disk 12. This second connection portion 68 is formed, for example, of a soft magnetic material, and together with the main magnetic pole 60 and the leader core 64, forms a magnetic circuit. The second coil 72 of the recording head 58 is configured to be wound around the magnetic circuit (second core) including the main magnetic pole 60 and the leader core 64, applying a magnetic field to the magnetic circuit. The second coil 72 is wound, for example, around the second connection portion 68. Furthermore, a non-conductive material 52a can be inserted into a portion of the second connection portion 68. The second connection portion 68 is connected to the upper part of the main magnetic pole 60, i.e., the portion of the main magnetic pole 60 that exits the ABS13, via the non-conductive material 52a. Alternatively, a non-magnetic material can be inserted instead of the non-conductive material 52a.

[0061] The second coil 72 is wound in the opposite direction to the first coil 70. The first coil 70 and the second coil 72 are connected to terminals 95 and 96, respectively, which are connected to the head amplifier IC 30 via wiring. The second coil 72 can also be connected in series with the first coil 70. Furthermore, the current supply to the first coil 70 and the second coil 72 can be controlled independently. The current supplied to the first coil 70 and the second coil 72 is controlled by the head amplifier IC 30 and the main controller 40.

[0062] Figure 4 This is a diagram obtained by viewing the recording head in the magnetic head used in the embodiment from the air support side.

[0063] As shown in the figure, the recording head 58 has a main magnetic pole 60 and an auxiliary magnetic pole 62. The auxiliary magnetic pole 62 is disposed with an open write gap WG between the main magnetic pole 60 and the main magnetic pole 60, forming a magnetic circuit together. An STO (Spin-Torque Oscillator) serving as a high-frequency oscillation element 65 is disposed between the end face 60-1 on the write gap WG side of the main magnetic pole 60 and the auxiliary magnetic pole 62. Side shields 112 are disposed with an open side gap SG on both sides 60-2 and 60-3 of the main magnetic pole 60 in the track width direction. At least one flux control layer (FCL) 111 can be disposed on the side gap SG side of the main magnetic pole 60. Here, a pair of FCLs 111 for controlling the oscillation frequency of the high-frequency oscillation element 65 are respectively disposed on both sides 60-2 and 60-3 of the main magnetic pole 60.

[0064] Figure 5 Showing the Figure 4 A diagram illustrating the configuration of the magnetic head and the magnetic recording medium.

[0065] Figure 5 The 16-head designation indicates Figure 4The X-X' section of the magnetic head 16. The magnetic recording medium 12 is configured opposite to the ABS 13 of the magnetic head 16.

[0066] Based on ABS13, FCL111 can be positioned further back than STO65. This reduces leakage magnetic fields, such as those caused by interference with adjacent orbitals.

[0067] like Figure 1 As shown, the head amplifier IC 30 that drives the magnetic head 16 and the recording head 58 includes: a recording current supply circuit 81 that supplies recording current to the first coil 70 and the second coil 72 via connection terminals 95 and 96; an oscillation element current supply circuit 82, which is a high-frequency oscillation element control unit, that supplies bias current to the STO 65 via wiring (not shown) and connection terminals 91 and 92; a heater voltage supply circuit 83 that supplies heater voltage to the recording heater 19a and the playback heater 19b via wiring (not shown) and connection terminals 97 and 98; a read voltage supply circuit 84 that reads the playback signal recorded on the disk 12 based on the voltage applied to the playback element of the magnetic head; and a flux control element current supply circuit 85, which is a flux control element control unit, that supplies bias current to the FCL 111 via wiring 91, wiring 93 and the side shield 112 of the lead core 64. Furthermore, although not shown, it includes a timing calculation unit and a recording current waveform generator (not shown). The timing calculation unit controls the timing of the current flowing in the recording current supply circuit 81 and the timing of the current flowing in the oscillation element current supply circuit 82. The recording current waveform generator generates a recording current waveform based on the recording pattern signal generated in the R / W channel 42.

[0068] like Figures 1-5 As shown, the disk drive 10 according to the embodiment uses microwave-assisted magnetic recording. Within the head amplifier IC 30, there is an oscillator current supply circuit 82 for driving the STO 65 and a flux control element current supply circuit 85 for driving the FCL 111. The return pole 62 and the side shield 112 can be separated, thereby ensuring that the flux control element current supply circuit 85, as shown by arrow 161b, flows back from the main pole 60 to the side shield via the FCL 111. A bias current If can be supplied to the FCL 111 in the direction indicated by arrow 161b. Furthermore, as shown by arrow 161a, a bias current Is can be supplied to the STO 65 by supplying current to the oscillator current supply circuit 82 in the direction in which electrons flow from the main pole to the return pole 62. The oscillator current supply circuit 82 is ensured by providing a first connection portion 50 at the position of the head 16 away from the ABS 13, where the main pole 60 and the return pole 62 are joined via an insulating layer 52.

[0069] According to the implementation, the circuit can be divided into an oscillation element current supply circuit 82 that supplies current to the STO and a flux control element current supply circuit 85 that supplies current to the FCL, and these circuits can be set up independently. Therefore, each component of the STO65 and FCL111 can be controlled independently. By controlling the bias current If supplied to the FCL111 and the bias current Is supplied to the STO65, the magnetic field strength applied to the write gap of the STO65 can be adjusted according to the magnetization state of the FCL111.

[0070] To resonate and assist the magnetization reversal of the magnetic recording layer 103 using a high-frequency magnetic field from STO65, the frequency of the high-frequency magnetic field, i.e., the oscillation frequency of the magnetization of STO65, can be matched with the resonant frequency of the magnetic recording layer 103. Since both are magnetization oscillations based on ferromagnetic resonance, the oscillation frequency of STO65 depends on the effective magnetic field applied to STO65, i.e., the magnetic field strength within the write gap WG, while the resonant frequency of the magnetic recording layer 103 depends on the anisotropic magnetic field (Hk) of the magnetic recording layer 103. To assist recording of the magnetic recording layer 103, STO65 can be oscillated at the optimal frequency for the medium. The oscillation frequency of STO65 varies according to the magnetic field strength within the write gap WG, which varies according to the width PWA of the main magnetic pole 60. Therefore, sometimes, due to variations in the head size, it can be difficult to achieve magnetization reversal resonance in the medium. Therefore, independently controlling the magnetic field within the gap is effective. According to the implementation, even if there is a deviation between the resonant frequency of the medium and the oscillation frequency of the STO65 of each magnetic head 16, the oscillation frequency can be adjusted independently for each magnetic head by driving the FCL111 to match the resonant frequency of the medium. Therefore, the fluctuation of the auxiliary effect of each magnetic head and the resulting attenuation of the auxiliary effect can be suppressed.

[0071] Figure 6 This is a diagram showing the flow of magnetic flux in the head when no drive current is supplied to the FCL.

[0072] Figure 7 This is a diagram showing the flow of magnetic flux in the head when a drive current is applied to the FCL.

[0073] Figure 8 This is observed along the cross-section of the track from the direction of arrow 162. Figure 6 The diagram is obtained by observing the flow of magnetic flux through the magnetic head.

[0074] Figure 9 This is observed along the cross-section of the track from the direction of arrow 162. Figure 7 The diagram is obtained by observing the flow of magnetic flux through the magnetic head.

[0075] like Figure 6As shown, without a drive current being supplied to FCL111, as indicated by arrow 124, the magnetization direction of FCL111 becomes a shape that coordinates with the magnetization direction of the main magnetic pole 60 indicated by arrow 121 and the magnetization direction within the side shield 112 indicated by arrow 123. The magnetic field from the main magnetic pole 60 becomes a closed shape within the main magnetic pole 60 and the side shield 112, as indicated by arrow 122. Therefore, as... Figure 8 As shown, the magnetic field strength guided into the write gap WG decreases as indicated by arrow 132. On the other hand, as... Figure 7 As shown, by driving a current within FCL111, as indicated by arrow 124a, the magnetization direction of FCL111 is reversed to the opposite direction to the magnetization within the main magnetic pole 60 and the side shield 112. This effectively makes the permeability within the side gap SG negative, and the closed magnetic field within the side gap SG, as indicated by arrow 122a, is guided into the write gap WG. Consequently, the magnetic field strength within the write gap WG increases, as indicated by arrow 132a. Thus, by controlling the magnetization of FCL111, the oscillation frequency of STO65, which depends on the magnetic field strength within the write gap WG, can be independently controlled.

[0076] The following examples illustrate the disk drive involved in the implementation.

[0077] (Example 1)

[0078] Figure 10 This is a schematic diagram showing the cross-sectional configuration of the read / write head used in the disk device according to Embodiment 1.

[0079] The disk device involved in Example 1 has the following features: Figure 10 The magnetic head shown is constructed as shown.

[0080] In Embodiment 1, the magnetic head 16', besides having an STO65' instead of STO65 and an FCL111' instead of FCL111, has the same... Figure 4 Same composition.

[0081] STO65' has a third non-magnetic conductive layer 65a, a spin injection layer 65b, a fourth non-magnetic conductive layer 65c, an oscillation layer 65d, and a fifth non-magnetic conductive layer 65e sequentially disposed on the trailing end 60-1 of the main magnetic pole 60. Here, the third non-magnetic conductive layer 65a can be omitted as needed. Alternatively, at the top end 60a of the main magnetic pole 60, the order of film formation of the third non-magnetic conductive layer 65a, the spin injection layer 65b, the fourth non-magnetic conductive layer 65c, the oscillation layer 65d, and the fifth non-magnetic conductive layer 65e can be reversed, and a bias current is applied to the polarity of the top end 62a of the return magnetic pole 62, which flows through the fifth non-magnetic conductive layer 65e, the oscillation layer 65d, the fourth non-magnetic conductive layer 65c, the spin injection layer 65b, and the third non-magnetic conductive layer 65a.

[0082] FCL111' has a first non-magnetic conductive layer 111a, a magnetization reversal layer 111b, and a second non-magnetic conductive layer 111c disposed on the side shielding end faces 60-2 and 60-3 of the main magnetic pole 60. Here, the first non-magnetic conductive layer 111a can be omitted as needed. Alternatively, the order of film formation of the first non-magnetic conductive layer 111a, the magnetization reversal layer 111b, and the second non-magnetic conductive layer 111c on the side shielding end faces 60-2 and 60-3 of the main magnetic pole 60 can be reversed, and a bias current can be applied to the polarity of the current flowing from the side shielding end faces 60-2 and 60-3 through the second non-magnetic conductive layer 111c, the magnetization reversal layer 111b, and the first non-magnetic conductive layer 111a to the side shielding member 112.

[0083] Here, as two FCL111' disposed in the side gap SW, films were formed in the following order, starting from the main magnetic pole 60 side: the first non-magnetic conductive layer 111a is 20 nm Ta, the magnetization reversal layer 111b is 5 nm NiFe, and the second non-magnetic conductive layer 111c is 2 nm Cu.

[0084] In addition, as STO65', starting from the main magnetic pole 60 side, the film was formed in the following order: the third non-magnetic conductive layer 65a is 6 nm Ta, the spin-injected layer 65b is 3 nm NiFe, the fourth non-magnetic conductive layer 65c is 2 nm Cu, the oscillating layer 65d is 8 nm FeCo, and the fifth non-magnetic conductive layer 65e is 6 nm Ta.

[0085] In addition, as the main magnetic pole 60, a header with a recording width PWA of 45nm was made in ABS13.

[0086] As shown by arrow 116b, by applying a bias current If to FCL111 in the direction of electron flow from the main magnetic pole 60 side to the side shield 112 side, the magnetization reversal layer 111b is reversed due to the spin torque reflected by the second non-magnetic conductive layer 111c. Furthermore, as shown by arrow 161a, by applying a bias current Is to STO65' in the direction of electron flow from the main magnetic pole 60 to the return magnetic pole 62 side, the magnetization of the oscillating layer 65d oscillates in-plane due to the spin torque between the spin injection layer 65b and the oscillating layer 65d. In this configuration, the oscillation frequency was observed by applying a bias current Is to STO65 while changing the bias current If applied to FCL111. The results are expressed as follows: Figure 11 .

[0087] Figure 11 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in the disk device of Embodiment 1.

[0088] Curve 151 represents the change in the oscillation frequency of STO65 relative to the bias current If supplied to FCL111.

[0089] As shown in the figure, it can be seen that as the bias current If increases, the magnetization of FCL111 reverses, thereby increasing the magnetic field applied to the write gap of STO65. Consequently, the oscillation frequency of STO65 also increases accordingly.

[0090] For example, when the resonant frequency of the magnetic recording layer 103 of the magnetic recording medium 12 is 24 GHz, the oscillation frequency is as low as ~20 GHz when FCL111 is not driven. Therefore, it is difficult to make the magnetic recording layer 103 resonate. However, by adjusting If to Figure 8 The A oscillation frequency is matched with the optimal range 141 (~24 GHz) of the resonant frequency of the recording layer containing the medium, thereby enabling the magnetization of the magnetic recording layer 103 to resonate and efficiently assisting the reversal of the magnetization of the medium.

[0091] Thus, in the disk device 10 according to the embodiment, in the high-frequency assisted magnetic recording method in which a bias current is passed through the STO65, which is provided between the main magnetic pole 60 and the auxiliary magnetic pole 62, and the STO65 is oscillated to perform assisted recording, an FCL111 is also provided between the main magnetic pole 60 and the side shield 112. By adjusting the magnetization state of the FCL111, the magnetic field strength of the external magnetic field applied to the STO65 can be adjusted, thereby adjusting the oscillation frequency of the STO65.

[0092] (Example 2)

[0093] The disk device according to Embodiment 2 has a read / write head that differs from that in Embodiment 1, except for the width PWA of the main magnetic pole 60. Figure 10 The structure shown is the same as the structure.

[0094] Five magnetic heads were fabricated by varying the width PWA of the air support surface of the main magnetic pole 60 within a range of approximately 38–55 nm. These heads were then assembled to create five disk drives. By introducing a current into FCL111' in the direction of electron flow from the main magnetic pole 60 side to the side shield 112 side, the magnetization reversal layer 111b reverses due to the spin torque reflected by the second non-magnetic conductive layer 111c. Furthermore, by introducing a current into STO65' in the direction of electron flow from the main magnetic pole 60 to the return magnetic pole 62 side, the magnetization of the oscillation layer 65d oscillates in-plane due to the spin torque between the spin injection layer 65b and the oscillation layer 65d.

[0095] Figure 12 A graph showing the relationship between the width PWA of the head main magnetic pole and the STO oscillation frequency in the case of no If input is shown.

[0096] 152 shows the results obtained by observing the oscillation frequency when the STO is driven in this configuration without the If input. For example... Figure 12 As shown, it can be confirmed that the larger the width PWA of the main magnetic pole 60, the greater the magnetic field strength from the main magnetic pole 60, that is, the greater the magnetic field strength applied within the write gap WG of STO65. Therefore, the oscillation frequency of STO65 tends to increase. Consequently, the divergence between the resonant frequency of the magnetic recording layer 103 and the oscillation frequency of STO65 also changes with PWA. Therefore, the adjustment of the magnetization reversal degree of FCL111, that is, the If introduced into FCL111, also varies according to PWA.

[0097] Figure 13 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in an example of the disk device of Embodiment 2.

[0098] Figure 14 This is a graph showing the relationship between the bias current If and the oscillation frequency of STO in another example of the disk device of Embodiment 2.

[0099] Figure 13 Curve 153 relates to disk devices using 38nm PWA heads. Figure 14 Curve 154 shows the results obtained by observing the STO oscillation frequency while changing the bias current If for a disk device using a 55nm PWA head.

[0100] like Figure 13As shown, with a PWA of 38 nm, the magnetic field strength within the writing gap is small, and the oscillation frequency is low when the If current is zero. Therefore, it is considered that to match the oscillation frequency with the optimal range of 141 (~24 GHz) of the resonant frequency of the containing dielectric recording layer, the If current needs to be increased to the value of B (approximately 4 mA). On the other hand, as... Figure 14 As shown, when the magnetic field strength within the writing gap is high and the original oscillation frequency is high (PWA = 55 nm), the frequency can be optimized by applying a value of C (approximately 0.7–0.8 mA) to If. Therefore, the optimal If for optimizing the oscillation frequency of the STO varies depending on the PWA.

[0101] Figure 15 A graph showing the optimal relationship between If and PWA when the oscillation frequency is adjusted to 24 GHz is displayed.

[0102] 155 represents the optimal If statement relative to PWA. For example... Figure 15 As shown, it can be seen that in order for the recording layer medium to resonate independently of head size fluctuations, the larger the PWA, the lower the If can be adjusted.

[0103] Several embodiments of the present invention have been described above, but these embodiments are merely illustrative and not intended to limit the scope of the invention. These novel embodiments can be implemented in a wide variety of other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A disk drive, characterized in that, include: The magnetic head includes a main magnetic pole, an auxiliary magnetic pole, a side shield, a high-frequency oscillation element, and a magnetic flux control element. The auxiliary magnetic pole is disposed with an open write gap to the main magnetic pole, forming a magnetic circuit together with the main magnetic pole. The side shield is disposed with an open side gap on both sides of the main magnetic pole in the track width direction. The high-frequency oscillation element is disposed in the write gap between the main magnetic pole and the auxiliary magnetic pole. The magnetic flux control element is disposed in the side gap between the main magnetic pole and the side shield to control the oscillation frequency of the high-frequency oscillation element. The oscillation element control unit controls the bias current supplied to the high-frequency oscillation element; as well as The flux control element control unit controls the bias current supplied to the flux control element.

2. The disk drive according to claim 1, characterized in that, At the position where the magnetic head has moved away from the air support surface, there is a joint where the main magnetic pole and the auxiliary magnetic pole are joined together via an insulating layer.

3. The disk drive according to claim 1, characterized in that, The auxiliary magnetic pole is separated from the side shield.

4. The disk drive according to claim 1, characterized in that, The flux control element includes a first non-magnetic conductive layer disposed on the main magnetic pole, a magnetization reversal layer disposed on the first non-magnetic conductive layer, and a second non-magnetic conductive layer disposed on the magnetization reversal layer.

5. The disk drive according to claim 1, characterized in that, The high-frequency oscillation element includes a third non-magnetic conductive layer disposed on the main magnetic pole, a spin injection layer disposed on the third non-magnetic conductive layer, a fourth non-magnetic conductive layer disposed on the spin injection layer, an oscillation layer disposed on the fourth non-magnetic conductive layer, and a fifth non-magnetic conductive layer disposed on the oscillation layer.

6. The disk drive according to claim 1, characterized in that, It is a disk drive device with two or more read / write heads. It includes: a first magnetic head having a first main magnetic pole having a first width in the track width direction and being subjected to a first bias current; and a second magnetic head having a second main magnetic pole having a second width in the track width direction that is larger than the first width and being subjected to a second bias current that is lower than the first bias current.

7. The disk drive according to claim 1, characterized in that, Viewed from the air support surface, the flux control element is recessed relative to the high-frequency oscillation element.

8. The disk drive according to claim 1, characterized in that, The oscillation element control unit and the magnetic flux control element control unit are set up independently of each other.

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