Patent Grant
8675308
This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2012-146891, filed Jun. 29, 2012, the entire contents of which are incorporated herein by reference.
Embodiments described herein relate generally to a magnetic recording head having a high-frequency oscillator, and a disk drive comprising the magnetic recording head.
As a disk drive, for example, a magnetic disk drive comprises a magnetic disk disposed in a case, spindle motor which supports and rotates the magnetic disk, a magnetic head which reads information from and writes information into the magnetic disk, and a carriage assembly which supports the magnetic head movably relative to the magnetic disk. The magnetic head has a slider attached to a suspension, and a head portion provided in the slider. The head portion comprises a recording head and a reproducing head.
Recently, a perpendicular magnetic recording magnetic head has been suggested for higher recording density, higher capacity, or a smaller size of a magnetic disk drive. In such a magnetic head, the recording head has a main magnetic pole which generates a perpendicular magnetic field, a trailing shield located on the trailing side of the main magnetic pole across a write gap to close a magnetic path between this trailing shield and the magnetic path, and a coil for passing a magnetic flux through the main magnetic pole. A high-frequency assist head has been suggested. In this high-frequency assist head, a high-frequency oscillator is provided between a medium-side end of a trailing shield and a main magnetic pole, and a current is passed to the high-frequency oscillator through the main magnetic pole and the trailing shield.
In the high-frequency assist recording head, the high-frequency oscillator is located between the main magnetic pole and the trailing shield which is located on the trailing side of the main magnetic pole, that is, the high-frequency oscillator is located on the trailing side of the main magnetic pole. A drive current is passed through this high-frequency oscillator, and the magnetization of an oscillating layer is oscillated. As a result, a great high-frequency magnetic field can be generated. Recording ability is improved in a region where the high-frequency magnetic field is superposed on a recording magnetic field coming from the main magnetic pole, and stable recording characteristics are obtained.
Increased intensity of high-frequency magnetic field is required for enhanced high-frequency recording. In this case, the high-frequency magnetic field generated on the trailing side of the main magnetic pole is also increased, and recorded bits may be reversed in the region where the high-frequency magnetic field is superposed on an effective magnetic field coming from the trailing-side end.
Various embodiments will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment, a magnetic recording head comprises: a disk-facing surface configured to face a recording layer of a recording medium; a main magnetic pole comprising a distal end located on the disk-facing surface and configured to apply a recording magnetic field to the recording layer of the recording medium; a leading shield on a leading side of the main magnetic pole, opposed to the distal end of the main magnetic pole across a gap; a high-frequency oscillator between the leading shield and the distal end of the main magnetic pole; and a recording coil configured to excite the main magnetic pole with a magnetic field.
(First Embodiment)
A magnetic disk 12 as a recording medium and a mechanical unit (drive unit) are provided on the base 10a. The mechanical unit comprises a spindle motor 13 which supports and rotates the magnetic disk 12, a plurality of, for example, two magnetic heads 33 which record information in the magnetic disk or reproduce information from the magnetic disk, a head actuator 14 which supports the magnetic heads 33 movably relative to the surface of the magnetic disk 12, and a voice coil motor (hereinafter referred to as a VCM) 16 which rotates and positions the head actuator. Moreover, a ramp load mechanism 18, a latch mechanism 20, and a substrate unit 17 are provided on the base 10a. The ramp load mechanism 18 holds the magnetic heads 33 at a distance from the magnetic disk 12 when the magnetic heads 33 have moved to the outer circumference of the magnetic disk 12. The latch mechanism 20 holds the head actuator 14 at a refuge position when, for example, an impact is caused to the HDD. Electronic components such as a preamplifier and a head IC are mounted on the substrate unit 17.
A control circuit substrate 25 is screwed to the outer surface of the base 10a, and is located to face the bottom wall of the base 10a. The control circuit substrate 25 controls the operations of the spindle motor 13, the VCM 16, and the magnetic heads 33 via the substrate unit 17.
As shown in
The head actuator 14 comprises a bearing 21 fixed to the bottom wall of the base 10a, and a plurality of arms 27 extending from the bearing 21. The arms 27 are located parallel to the surface of the magnetic disk 12 and located a predetermine distance apart from each other. The arms 27 extend from the bearing 21 in the same direction. The head actuator 14 comprises elastically deformable elongated plate-like suspensions 30. The suspension 30 comprises a leaf spring. The proximal end of the suspension 30 is fixed to the distal end of the arm 27 by spot welding or adhesive bonding, and extends from the arm. Each of the suspensions 30 may be formed integrally with the corresponding arm 27. The magnetic heads 33 are supported on the extending ends of the respective suspensions 30. The arm 27 and the suspension 30 constitute a head suspension. This head suspension and the magnetic heads 33 constitute a head suspension assembly.
As shown in
Each of the magnetic heads 33 is electrically connected to a later-described main FPC 38 via a relay flexible printed circuit board (hereinafter referred to as a relay FPC) 35 fixed to the suspension 30 and the arm 27.
As shown in
The VCM 16 has an unshown support frame extending from the bearing 21 in a direction opposite to the arm 27, and a voice coil supported by the support frame. When the head actuator 14 is incorporated in the base 10a, the voice coil is located between a pair of yokes 34 fixed to the base 10a, and constitute the VCM 16 together with the yokes and magnets fixed to the yokes.
Electricity is passed through the voice coil of the VCM 16 while the magnetic disk 12 is rotating. As a result, the head actuator 14 rotates, and the magnetic heads 33 are moved to and positioned on a desired track of the magnetic disk 12. In this case, the magnetic heads 33 are moved between the inner peripheral edge and outer peripheral edge of the magnetic disk along the diametrical direction of the magnetic disk 12.
Now, the configurations of the magnetic disk 12 and the magnetic head 33 are described in detail.
As shown in
As shown in
The slider 42 has a rectangular disk-facing surface (air bearing surface (ABS)) 43 that faces the surface of the magnetic disk 12. The slider 42 floats in response to airflow C produced between the disk surface and the disk-facing surface 43 by the rotation of the magnetic disk 12. The direction of the airflow C corresponds to a rotation direction B of the magnetic disk 12. The slider 42 is located relative to the surface of the magnetic disk 12 so that the longitudinal direction of the disk-facing surface 43 substantially corresponds to the direction of the airflow C.
The slider 42 has a leading end 42a located on the inflow side of the airflow C, and a trailing end 42b located on the outflow side of the airflow C. For example, an unshown leading step, a trailing step, a side step, and a negative pressure cavity are formed on the disk-facing surface 43 of the slider 42.
As shown in
The reproduction head 54 comprises a magnetic film 55 showing magnetoresistive effect, and shield films 56 and 57 located on the trailing side and leading side of the magnetic film 55 across the magnetic film 55. The lower ends of the magnetic film 55 and the shield films 56 and 57 are exposed in the disk-facing surface 43 of the slider 42.
The magnetic recording head 58 is provided on the trailing end 42b of the slider 42 as opposed to the reproduction head 54.
As shown in
The main magnetic pole 60 extends substantially perpendicularly to the surface of the magnetic disk 12. The main magnetic pole 60 has a distal end 60a located in the vicinity of the disk-facing surface 43, and a top (back gap) located inwardly (upwardly) apart from the disk-facing surface. The distal end 60a of the main magnetic pole 60 is tapered toward the disk surface. The distal end 60a of the main magnetic pole 60 is, for example, trapezoidal or rectangular in section. The distal face of the main magnetic pole 60 is exposed in the disk-facing surface 43 of the slider 42. The width of the distal face of the main magnetic pole 60 substantially corresponds to the width of the track in the magnetic disk 12.
As shown in
The leading shield 64 has a first connecting portion 68 joined to the back gap of the main magnetic pole 60 at a distance from the magnetic disk 12. The first connecting portion 68 is joined to the main magnetic pole 60 via a nonconducting layer 69, and is electrically insulated from the main magnetic pole 60 and the leading shield 64 in the back gap. The first connecting portion 68 is made of, for example, a soft magnetic body. Together with the main magnetic pole 60 and the leading shield 64, the first connecting portion 68 forms the magnetic core that constitutes a magnetic circuit. The recording head 58 has the first recording coil 70. The first recording coil 70 is located to be wound around the magnetic circuit (magnetic core) that includes the main magnetic pole 60 and the leading shield 64. The first recording coil 70 applies a magnetic field to this magnetic circuit. The first recording coil 70 is wound around the first connecting portion 68, for example, between the main magnetic pole 60 and the leading shield 64.
Furthermore, the second recording coil 72 is located on the trailing side of the main magnetic pole 60. A pair of coils comprising the second recording coil 72 and the first recording coil 70 is configured so that the main magnetic pole 60 intervenes in between. Terminals 95 and 96 are connected to the first and second coils 70 and 72, respectively. A power supply 98 is connected to the terminals 95 and 96. The first coil 70 is connected in series to the second coil 72. The control of current supply to the first coil 70 and the second coil 72 may be separated. The current supplied to the first coil 70 and the second coil 72 is controlled by a controller of the HDD.
Electricity is passed through the first and second recording coils 70 and 72. As a result, the main magnetic pole 60 is magnetized, and a recording magnetic field is applied to the magnetic disk 12. It is also possible to have a structure without one of a pair of recording coils. In this case, heat generated by the coil during recording operation is reduced, and the change of recording characteristics caused by the thermal expansion of the main magnetic pole can be inhibited.
The distance of the gap (back gap) between the back gap of the main magnetic pole 60 and the first connecting portion 68 of the leading shield 64 is smaller than the distance between the main magnetic pole 60 and the leading shield 64 in the vicinity of the coil 70. Therefore, an efficient magnetic path is formed between the main magnetic pole 60 and the leading shield 64, and a great recording magnetic field can be generated on the leading side of the main magnetic pole. The main magnetic pole 60 and the leading shield 64 are electrically insulated from each other in the vicinity of the back gap.
The spin torque oscillator 74 is located between the distal end 60a of the main magnetic pole 60 and the distal end of the leading shield 64 in the vicinity of the disk-facing surface 43. The spin torque oscillator 74 is configured by stacking, for example, a foundation layer, a spin injection layer, an intermediate layer, an oscillating layer, and a gap layer in order from the main magnetic pole 60 to the leading shield 64.
Terminals 90 and 91 are connected to the main magnetic pole 60 and the leading shield 64. The terminals 90 and 91 are connected to a power supply 94. A current circuit is configured so that a drive current can be passed in series through the main magnetic pole 60, the spin torque oscillator 74, and the leading shield 64 from the power supply 94. Electricity is passed through the spin torque oscillator 74, and a high-frequency magnetic field is thereby applied to the recording layer of the magnetic disk 12 from the spin torque oscillator.
As shown in
Consequently, in the vicinity of the disk-facing surface 43, the leading shield 64, the spin torque oscillator 74, the main magnetic pole 60, and the trailing shield 62 are arranged in the track center in order from the leading side. In the magnetic recording head 58 described above, an alloy containing at least one kind selected from the group consisting of Fe, Co, and Ni or a compound can be selected and used as the soft magnetic body that constitutes the main magnetic pole 60, the trailing shield 62, and the leading shield 64.
As shown in
In the embodiment, the gap (distance) between the main magnetic pole 60 and the leading shield 64 is formed at 40 nm. The spin torque oscillator 74 having a core width of 40 nm and an element height of 40 nm is inserted in the gap between the main magnetic pole 60 and the leading shield 64. The spin torque oscillator 74 comprises an oscillating layer, an intermediate layer, and a spin injection layer. The oscillating layer is 15 nm in thickness, and is made of FeCoNi which is nonmagnetic and which has a high saturation flux density of 2T. The intermediate layer is 3 nm in thickness, and is made of Cu having a great spin diffusion length. The spin injection layer is 12 nm in thickness, and is made of Co/Ni artificial lattice having high coercive force and high spin polarizability. The spin torque oscillator 74 is electrically conducted to the main magnetic pole 60 and the leading shield 64 via a metal layer such as Ta or Ru having high electric conductivity. Thus, the main magnetic pole 60 and the leading shield 64 can be used to pass the drive current to the spin torque oscillator 74. As a result, a high-frequency magnetic field is applied to the recording medium from the spin torque oscillator 74.
In order to efficiently generate a recording magnetic field from the disk-facing surface 43, the distal end 60a of the main magnetic pole 60 is tapered toward the disk-facing surface 43. That is, the shape of the trailing side of the main magnetic pole 60 is sloped so that a high recording magnetic field can be generated. The shape of the leading side may also be sloped. The size of the main magnetic pole 60 in the disk-facing surface 43 in a core width direction (track width direction) is 50 nm, and the size in a down track direction (track direction) is 30 nm.
As shown in
The trailing shield 62 is formed so that the ratio of the length TSW of a part of the trailing shield 62 facing the distal end of the main magnetic pole 60 in the track width direction to the length TST in the down track direction is 5≧TSW/TST≧30.
According to the HDD having the configuration described above, the head actuator 14 is rotated by the driving of the VCM 16, and the magnetic head 33 is moved to and positioned on a desired track of the magnetic disk 12. The magnetic head 33 floats in response to airflow C produced between the disk surface and the disk-facing surface 43 by the rotation of the magnetic disk 12. During the operation of the HDD, the disk-facing surface 43 of the slider 42 faces the disk surface to keep a clearance therebetween. As shown in
In the writing of information, as shown in
A position at 0.2 μm in the down track direction in
As the spin torque oscillator 74 is provided between the main magnetic pole 60 and the leading shield 64, the spin torque oscillator 74 is not subject to the write gap magnetic field. Thus, the write gap WG can be made smaller to increase the intensity of the write gap magnetic field, and recording density can be further improved.
In consequence, according to the present embodiment, it is possible to obtain a magnetic recording head and a disk drive comprising this magnetic recording head in which recording ability is improved, stable recording/reproduction characteristics can be obtained, and higher recording density can be obtained.
Now, HDDs according to other embodiments are described. In the other embodiments described below, the same components as those in the previously described first embodiment are provided with the same reference signs and are not described in detail. The differences between the other embodiments and the first embodiment are mainly described in detail.
(Second Embodiment)
The magnetic recording head 58 comprises a leading shield 64, a spin torque oscillator 74 as a high-frequency oscillator, a main magnetic pole 60, and a trailing shield 62. In a track center, the leading shield 64, the spin torque oscillator 74, the main magnetic pole 60, and the trailing shield 62 are arranged in order from a leading side. According to the second embodiment, the trailing shield 62 has a distal end 62a that faces the trailing side of a distal end 60a of the main magnetic pole 60 across a write gap. The trailing shield 62 extends further upward from a disk-facing surface 43. The trailing shield 62 has a second connecting portion 62c joined to the back gap of the main magnetic pole 60 at a distance from a magnetic disk 12. The second connecting portion 62c is joined to the main magnetic pole 60 via a nonconducting layer, and is electrically insulated from the main magnetic pole 60 and the trailing shield 62 in the back gap. A second recording coil 72 of the magnetic recording head 58 is located to be wound around a magnetic circuit (magnetic core) that includes the main magnetic pole 60 and the trailing shield 62. The second recording coil 72 applies a magnetic field to this magnetic circuit.
In the second embodiment, the configuration of the magnetic recording head 58 is the same as that in the first embodiment described above in other respects.
The back gap of the main magnetic pole 60 and the second joint 62c may be joined to the main magnetic pole 60 via a conductor. In this case, the same material can be used for the trailing shield 62 and the second joint 62c, the efficiency of the magnetic circuit of the main magnetic pole 60 and the trailing shield 62 is enhanced, and a greater recording magnetic field can be generated.
(Third Embodiment)
The magnetic recording head 58 comprises a leading shield 64, a spin torque oscillator 74 as a high-frequency oscillator, a main magnetic pole 60, and a trailing shield 62. In a track center, the leading shield 64, the spin torque oscillator 74, the main magnetic pole 60, and the trailing shield 62 are arranged in order from a leading side.
The trailing shield 62 has a distal end 62a that faces the trailing side of a distal end 60a of the main magnetic pole 60 across a write gap. The trailing shield 62 extends further upward from a disk-facing surface 43. The trailing shield 62 has a second connecting portion 62c joined to the back gap of the main magnetic pole 60 at a distance from a magnetic disk 12. The second connecting portion 62c is joined to the main magnetic pole 60 via a nonconducting layer, and is electrically insulated from the main magnetic pole 60 and the trailing shield 62 in the back gap. A second recording coil 72 of the magnetic recording head 58 is located to be wound around a magnetic circuit (magnetic core) that includes the main magnetic pole 60 and the trailing shield 62. The second recording coil 72 applies a magnetic field to this magnetic circuit.
In the third embodiment, the leading shield 64 is only provided in the vicinity of the disk-facing surface 43, and faces the leading side of the distal end 60a of the main magnetic pole 60 across a gap. In the disk-facing surface 43, the spin torque oscillator 74 is provided between the distal end 60a of the main magnetic pole 60 and the leading shield 64. The configuration of the magnetic recording head 58 is the same as those in the first and second embodiments described above in other respects.
Thus, in the third embodiment as well, it is possible to obtain a magnetic recording head and a disk drive comprising this magnetic recording head in which recording ability is improved, stable recording/reproduction characteristics can be obtained, and higher recording density can be obtained.
The back gap of the main magnetic pole 60 and the second joint 62c may be joined to the main magnetic pole 60 via a conductor. In this case, the same material can be used for the trailing shield 62 and the second joint 62c, the efficiency of the magnetic circuit of the main magnetic pole 60 and the trailing shield 62 is enhanced, and a greater recording magnetic field can be generated.
(Fourth Embodiment)
In the embodiment, the length TST of the trailing shield (TS) in the down track direction is 0.64 μm. The length TSW of the TS in a core width direction is changed within a given range of 1 to 25 μm. The size PWA of the main magnetic pole 60 in the core width direction (track width direction) is changed within a given range of 0.3 to 0.6 μm. In accordance with such shapes, an effective magnetic field Heff of the magnetic recording head 58 is found.
(Fifth Embodiment)
According to the present embodiment, the magnetic recording head 58 comprises a pair of side shields 78. The side shields 78 are magnetically isolated from the main magnetic pole 60 on a disk-facing surface 43 on both sides of the track width direction of the main magnetic pole 60. The side shields 78 are arranged to be joined to the trailing shield 62. The side shields 78 are joined to the leading shield 64.
In the present embodiment, the length TSW of the trailing shield (TS) 62 in a core width direction is 10 μm. The TS and the leading shield (LS) are connected to each other via the side shields 78 to form a full side shield configuration. The throat height of the TS 62 is changed within a given range of 0.05 to 0.3 μm. The length PT of the main magnetic pole 60 in a down track direction is changed within a given range of 0.02 to 0.04 μm. The length TST of the TS 62 in the down track direction is changed within a given range of 0.2 to 0.7 μm. In accordance with such shapes, an effective magnetic field Heff is found.
In the present embodiment, the leading shield 64 and the trailing shield 62 are connected to each other by the side shields 78 to form the full side shield configuration. However, similar advantages can be obtained by a side shield configuration in which one of the TS and the LS extends forward in an adjacent track direction of the main magnetic pole 60.
The size TSW of the trailing shield 62 in the core width direction may be equal to or more than the length of the leading shield 64 in the core width direction. In this case, the magnetic domain structures of the trailing shield 62 and the leading shield 64 are stabilized, and recorded bits of the adjacent track are not disturbed. Thus, stable recording is possible.
The length of the side shield 78 in the core width direction may be equal to or more than the length of the leading shield 64 in the core width direction. In this case, the magnetic domain structures of the side shield 78 and the leading shield 64 are stabilized, and recorded bits of the adjacent track are not disturbed. Thus, stable recording is possible. The length of the side shield 78 in the core width direction may be equal to or more than the length of the trailing shield 62 in the core width direction. In this case, the magnetic domain structures of the side shield 78 and the trailing shield 62 are stabilized, and recorded bits of the adjacent track are not disturbed. Thus, stable recording is possible.
While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
For example, the materials, shapes, and sizes of the elements that constitute the head portion can be changed when necessary. In the magnetic disk drive, the number of magnetic disks and magnetic heads can be increased when necessary. Various sizes of the magnetic disk can be selected.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-146891 | Jun 2012 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7724469 | Gao et al. | May 2010 | B2 |
| 7957098 | Yamada et al. | Jun 2011 | B2 |
| 8081397 | Funayama et al. | Dec 2011 | B2 |
| 8139322 | Yamada et al. | Mar 2012 | B2 |
| 8164854 | Takagishi et al. | Apr 2012 | B2 |
| 8238060 | Yamada et al. | Aug 2012 | B2 |
| 8270112 | Funayama et al. | Sep 2012 | B2 |
| 8295009 | Yamada et al. | Oct 2012 | B2 |
| 8400734 | Yamada et al. | Mar 2013 | B2 |
| 20020051330 | Heijden et al. | May 2002 | A1 |
| 20080137224 | Gao et al. | Jun 2008 | A1 |
| 20080218891 | Gubbins et al. | Sep 2008 | A1 |
| 20090052095 | Yamada et al. | Feb 2009 | A1 |
| 20090316304 | Funayama et al. | Dec 2009 | A1 |
| 20100007992 | Yamada et al. | Jan 2010 | A1 |
| 20100134922 | Yamada et al. | Jun 2010 | A1 |
| 20100195247 | Mochizuki et al. | Aug 2010 | A1 |
| 20100220415 | Yamada et al. | Sep 2010 | A1 |
| 20110090594 | Gurney et al. | Apr 2011 | A1 |
| 20110228423 | Koui et al. | Sep 2011 | A1 |
| 20110299192 | Yamada et al. | Dec 2011 | A1 |
| 20110300409 | Yamada et al. | Dec 2011 | A1 |
| 20120268844 | Yamada et al. | Oct 2012 | A1 |
| Number | Date | Country |
|---|---|---|
| 2009-070541 | Apr 2009 | JP |
| 2010-003353 | Jan 2010 | JP |
| 2010-182361 | Aug 2010 | JP |
| 2011-090765 | May 2011 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20140002924 A1 | Jan 2014 | US |
