U.S. patent application number 13/045603 was filed with the patent office on 2012-09-13 for microwave assisted magnetic head and magnetic disk device.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Tsutomu AOYAMA, Kiyoshi Noguchi, Tetsuya Roppongi, Isamu Sato, Yoshikazu Soeno.
Application Number | 20120230167 13/045603 |
Document ID | / |
Family ID | 46760683 |
Filed Date | 2012-09-13 |
United States Patent
Application |
20120230167 |
Kind Code |
A1 |
AOYAMA; Tsutomu ; et
al. |
September 13, 2012 |
MICROWAVE ASSISTED MAGNETIC HEAD AND MAGNETIC DISK DEVICE
Abstract
A microwave assisted magnetic head of the present invention
includes: at least two or more auxiliary coils that are arranged in
a periphery of a writing main pole; and microwave current supply
means that applies microwave currents to the at least two or more
auxiliary coils. The at least two or more auxiliary coils
respectively include linear body parts linearly arranged on an ABS
side, two of the linear body parts of the at least two or more
auxiliary coils are arranged in a substantially orthogonal
positional relationship, and the microwave current supply means is
configured such that the microwave current supply means changes
phase differences of the microwave currents applied respectively to
the at least two or more auxiliary coils. Therefore, the microwave
current can be easily controlled, and thus, a circularly polarized
magnetic field with high magnetization inversion efficiency can be
generated as an assistance magnetic field.
Inventors: |
AOYAMA; Tsutomu; (Tokyo,
JP) ; Roppongi; Tetsuya; (Tokyo, JP) ; Soeno;
Yoshikazu; (Tokyo, JP) ; Noguchi; Kiyoshi;
(Tokyo, JP) ; Sato; Isamu; (Tokyo, JP) |
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
46760683 |
Appl. No.: |
13/045603 |
Filed: |
March 11, 2011 |
Current U.S.
Class: |
369/13.01 ;
G9B/13.002 |
Current CPC
Class: |
G11B 5/314 20130101;
G11B 5/1278 20130101; G11B 2005/0024 20130101 |
Class at
Publication: |
369/13.01 ;
G9B/13.002 |
International
Class: |
G11B 13/04 20060101
G11B013/04 |
Claims
1. A microwave assisted magnetic head, comprising: a writing main
pole; a writing coil that generates a writing magnetic field at the
writing magnetic field part; at least two or more auxiliary coils
that are arranged in a periphery of the writing main pole; and
microwave current supply means that applies microwave currents to
the at least two or more auxiliary coils, wherein the at least two
or more auxiliary coils respectively include linear body parts
linearly arranged on an air bearing surface (ABS) side, two of the
linear body parts of the at least two or more auxiliary coils are
arranged in a substantially orthogonal positional relationship, and
the microwave current supply means is configured such that the
microwave current supply means changes a phase difference of the
microwave currents applied respectively to the at least two or more
auxiliary coils.
2. The microwave assisted magnetic head according to claim 1,
comprising: a writing main pole; an auxiliary pole; a writing coil
that generates a writing magnetic field at the writing main pole; a
first auxiliary coil and a second auxiliary coil that are arranged
between the writing main pole and the auxiliary pole; microwave
current supply means that applies microwave currents to the first
auxiliary coil and the second auxiliary coil, wherein the first
auxiliary coil includes a first linear body part linearly arranged
on an air bearing surface side (ABS), the second auxiliary coil
includes a second linear body part linearly arranged on the ABS
side, and the first linear body part and the second linear body
part are orthogonally arranged in a crossed shape in a separated
state, and the microwave current supply means is configured such
that the microwave current supply means changes a phase difference
of the microwave currents applied respectively to the first
auxiliary coil and the second auxiliary coil.
3. The microwave assisted magnetic head according to claim 2,
wherein the phase difference of the microwave currents applied
respectively to the first auxiliary coil and the second auxiliary
coil are configured at 90 degrees.
4. The microwave assisted magnetic head according to claim 2,
wherein a circularly polarized magnetic field is generated as an
assistance magnetic field by the microwave currents applied
respectively to the first auxiliary coil and the second auxiliary
coil.
5. The microwave assisted magnetic head according to claim 1,
comprising: a writing main pole; a shield (auxiliary) pole that is
formed so as to surround the writing main pole and that includes a
trailing side shield part, a first side shield part and a second
side shield part; a writing coil that generates a writing magnetic
field at the writing main pole; a first auxiliary coil that is
arranged between the writing main pole and the trailing side shield
part; a second auxiliary coil that is arranged between the writing
main pole and the first side shield part; a third auxiliary coil
that is arranged between the writing main pole and the second side
shield part; and microwave current supply means that applies
microwave currents to the first auxiliary coil, the second
auxiliary coil and the third auxiliary coil, wherein the first
auxiliary coil includes a first linear body part linearly arranged
on an air bearing surface (ABS) side, the second auxiliary coil
includes a second linear body part linearly arranged on the ABS
side, the third auxiliary coil includes a third linear body part
linearly arranged on the ABS side, the second linear body part and
the third linear body part are each arranged to have a
substantially orthogonal positional relationship relative to the
first linear body part, and the microwave current supply means is
configured such that the microwave current supply means changes
phase differences of the microwave currents applied respectively to
the first auxiliary coil, the second auxiliary coil and the third
auxiliary coil.
6. The microwave assisted magnetic head according to claim 5,
wherein the phase difference of the microwave currents applied
respectively to the second auxiliary coil and the third auxiliary
coil are configured at 90 degrees relative to the first auxiliary
coil.
7. The microwave assisted magnetic head according to claim 5,
wherein a circularly polarized magnetic field is generated as an
assistance magnetic field by the microwave currents applied
respectively to the first auxiliary coil, the second auxiliary
coil, and the third auxiliary coil.
8. A head gimbal assembly, comprising: a slider that includes the
microwave assisted magnetic head according to claim 1 and that is
arranged opposing the recording medium; and a suspension that
flexibly supports the slider.
9. A magnetic disk device, comprising: a slider that includes the
microwave assisted magnetic head according to claim 1 and that is
arranged opposing the recording medium; and a positioning device
that determines a position relative to the recording medium while
supporting the slider.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a microwave assisted thin
film magnetic head that provides an assistance function to generate
a circularly polarized magnetic field of a microwave band as an
assistance method for writing data signals to a magnetic recording
medium having a large coercive force to stabilize magnetization.
The present invention also relates to a magnetic disk device using
the microwave assisted thin film magnetic head.
[0003] 2. Description of the Background Technology
[0004] Conventional magnetic recording media, such as hard disks,
have undergone significant improvements in in-plane recording
density through improvements such as miniaturization of magnetic
particles and improvements in magnetic materials that configure
magnetic recording layers, miniaturization of the head fabrication
and the like. Furthermore, recent magnetic recording reproducing
devices primarily use a perpendicular magnetic recording method
that improves in-plane recording density by miniaturizing the
recording bit by magnetizing the recording layer in a perpendicular
direction to the surface of the magnetic recording medium. Further
improvements in the in-plane recording density are expected in the
future.
[0005] Meanwhile, because thermal fluctuation easily occurs in
recording magnetization with miniaturization of the recording bit
and magnetic particles, magnetic particles having a large
anisotropic magnetic field Hk and a large coercive force Hc are
preferred for use as material for the recording layer.
[0006] However, when magnetic particles with a large anisotropic
magnetic field Hk are used as the material for the recording layer,
the coercive force of the recording layer becomes a large value of
5 KOe or greater. Generally, a recording magnetic field of at least
twice the coercive force is said to be required when performing
saturation magnetic recording, which has been problematic for
saturation magnetization of the recording layer with conventional
magnetic head performance. In other words, the recording and
erasing of data on a magnetic disk has been problematic.
[0007] In response to these technical problems, a novel recording
method is proposed that uses microwave assistance. This method
attempts to reduce the magnetization-inversed magnetic field in the
perpendicular direction by forming a spin torque oscillator (STO)
configured by multiple layers of magnetic thin film in the gap
between the recording main pole of the perpendicular magnetic head
and the rear end shield to induce magnetization precession movement
by generating an in-plane microwave magnetic field by the
self-oscillation of the STO. (U.S. Pat. No. 6,785,092)
[0008] Specifically, a field generation layer (FGL) of the STO
configured from multiple layers of thin film self-oscillates at a
high frequency, and the leakage magnetic field generated from the
surface thereof is used as microwave assistance. The microwave
assisted magnetic field generated here is known as a linearly
polarized magnetic field. This assistance method is also known as a
self-excited type.
[0009] Compared to this assistance method, a head device is
proposed that arranges an auxiliary coil within a gap between the
main pole and the rear end shield and that performs microwave
assisted recording by generating a high frequency in-plane magnetic
field within the gap by driving high frequency current to the
auxiliary coil (Japanese Laid-Open Patent Application Publication
No. 2007-299460). This assistance method is also known as an
induced type. A magnetic head device that provides this type of
assistance method can apply high frequency in-plane
alternate-current magnetic fields in a microwave band to the
recording layer of the recording medium. The effect of such
assistance greatly reduces the perpendicular recording magnetic
field. Therefore, the recording and erasing of data can be
performed at a high-speed even with a recording layer having a
large coercive force. Furthermore, the in-plane alternate-current
magnetic fields generated by driving high frequency current to the
auxiliary coil provide the following characteristics:
[0010] 1) the frequency can be controlled on an order of ppm,
and
[0011] 2) the generated magnetic field is easily controlled by
controlling the amplitude of the high frequency current.
The microwave assisted magnetic field generated by this method is
also a linearly polarized magnetic field.
[0012] Meanwhile, analysis has advanced in recent years concerning
the advantageous effects of recording properties through microwave
assistance, and research has also been advancing around the effects
of the intensity, polarization, frequency, and the like, of
assistance magnetic fields.
[0013] Furthermore, it has been found that use of a circularly
polarized magnetic field is preferred for assistance, as a
circularly polarized magnetic field can generate a stronger
inversed magnetic field compared to a linearly polarized magnetic
field (Y. Wang et. al, J. Appl. Phys. 105, 07B902 (2009)). From
this perspective, the method disclosed in Japanese Laid-Open Patent
Application Publication No. 2010-003353 proposes a method for
generating a circularly polarized magnetic field in an induced type
in which an STO is used. In other words, because a lamination layer
plane 25a of a layered structure body 25 proposed in Japanese
Laid-Open Patent Application Publication No. 2010-003353 is tilted
relative to an air bearing surface (ABS) 61s, the high frequency
magnetic field Hac from the spin torque oscillator 10 is used to
act as a circularly polarized magnetic field in relation to the
magnetic recording layer 81 of the magnetic recording medium
80.
[0014] However, the configuration of the proposed STO has problems,
such as:
[0015] 1) the process is extremely complicated in that the
lamination of the magnetic thin film requires a minimum of five
layers;
[0016] 2) magnetic film having an extremely high magnetic
anisotropy is required for STO oscillation;
[0017] 3) control of the oscillation frequency is difficult as such
control is performed only by the current density infused into the
STO and as sudden changes can occur in the oscillation frequency as
a result of very small fluctuations in the current density, and
[0018] 4) the control parameters a microwave magnetic field that
can be generated are not clear, and the size of the generated
magnetic field is also not unapparent. Although a control parameter
is assumed to be current density that infuses energy, the
oscillation frequency changes when adjusting current density. As a
result, arbitrarily controlling both parameters is difficult.
In addition to these problems, forming the element at an incline
within the gap as in the proposed configuration is extremely
difficult from a process perspective which makes oscillation
control even more difficult.
[0019] The present invention is conceived based on these actual
circumstances and has an object to provide a specific head
structure and current drive method that generates a circularly
polarized magnetic field with high magnetization inversion
efficiency in an induced method for microwave assistance, or in
other words, that generates a circularly polarized magnetic field
in an induced method for microwave assistance, which has
characteristics, such as, 1) that frequency can be controlled on an
order of ppm, and 2) that a generated magnetic field can easily be
controlled by controlling the amplitude of high frequency
current.
SUMMARY
[0020] In order to solve the above drawbacks, a microwave assisted
magnetic head of the present invention is configured to include: a
writing main pole; a writing coil that generates a writing magnetic
field at the writing magnetic field part; at least two or more
auxiliary coils that are arranged in a periphery of the writing
main pole; and microwave current supply means that applies
microwave currents to the at least two or more auxiliary coils. The
at least two or more auxiliary coils respectively include linear
body parts linearly arranged on an air bearing surface (ABS) side,
two of the linear body parts of the at least two or more auxiliary
coils are arranged in a substantially orthogonal positional
relationship, and the microwave current supply means is configured
such that the microwave current supply means changes a phase
difference of the microwave currents applied respectively to the at
least two or more auxiliary coils.
[0021] Further, in a preferred embodiment of the present invention,
a microwave assisted magnetic head is configured to include a
writing main pole; an auxiliary pole; a writing coil that generates
a writing magnetic field at the writing main pole; a first
auxiliary coil and a second auxiliary coil that are arranged
between the writing main pole and the auxiliary pole; microwave
current supply means that applies microwave currents to the first
auxiliary coil and the second auxiliary coil. The first auxiliary
coil includes a first linear body part linearly arranged on an air
bearing surface side (ABS), the second auxiliary coil includes a
second linear body part linearly arranged on the ABS side, and the
first linear body part and the second linear body part are
orthogonally arranged in a crossed shape in a separated state, and
the microwave current supply means is configured such that the
microwave current supply means changes a phase difference of the
microwave currents applied respectively to the first auxiliary coil
and the second auxiliary coil.
[0022] Further, in a preferred embodiment of the present invention,
the microwave assisted magnetic head is configured such that the
phase difference of the microwave currents applied respectively to
the first auxiliary coil and the second auxiliary coil are
configured at 90 degrees.
[0023] Further, in a preferred embodiment of the present invention,
the microwave assisted magnetic head is configured such that a
circularly polarized magnetic field is generated as an assistance
magnetic field by the microwave currents applied respectively to
the first auxiliary coil and the second auxiliary coil.
[0024] Further, in a preferred embodiment of the present invention,
a microwave assisted magnetic head is configured to include: a
writing main pole; a shield (auxiliary) pole that is formed so as
to surround the writing main pole and that includes a trailing side
shield part, a first side shield part and a second side shield
part; a writing coil that generates a writing magnetic field at the
writing main pole; a first auxiliary coil that is arranged between
the writing main pole and the trailing side shield part; a second
auxiliary coil that is arranged between the writing main pole and
the first side shield part; a third auxiliary coil that is arranged
between the writing main pole and the second side shield part; and
microwave current supply means that applies microwave currents to
the first auxiliary coil, the second auxiliary coil and the third
auxiliary coil. The first auxiliary coil includes a first linear
body part linearly arranged on an air bearing surface (ABS) side,
the second auxiliary coil includes a second linear body part
linearly arranged on the ABS side, the third auxiliary coil
includes a third linear body part linearly arranged on the ABS
side, the second linear body part and the third linear body part
are each arranged to have a substantially orthogonal positional
relationship relative to the first linear body part, and the
microwave current supply means is configured such that the
microwave current supply means changes phase differences of the
microwave currents applied respectively to the first auxiliary
coil, the second auxiliary coil and the third auxiliary coil.
[0025] Further, in a preferred embodiment of the present invention,
the microwave assisted magnetic head is configured such that the
phase difference of the microwave currents applied respectively to
the second auxiliary coil and the third auxiliary coil are
configured at 90 degrees relative to the first auxiliary coil.
[0026] Further, in a preferred embodiment of the present invention,
the microwave assisted magnetic head is configured such that a
circularly polarized magnetic field is generated as an assistance
magnetic field by the microwave currents applied respectively to
the first auxiliary coil, the second auxiliary coil, and the third
auxiliary coil.
[0027] A head gimbal assembly of the present invention is
configured to include a slider that includes the microwave assisted
magnetic head according to claim 1 and that is arranged opposing
the recording medium; and a suspension that flexibly supports the
slider.
[0028] A magnetic disk device is configured to include: a slider
that includes the microwave assisted magnetic head according to
claim 1 and that is arranged opposing the recording medium; and a
positioning device that determines a position relative to the
recording medium while supporting the slider.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a perspective view that schematically illustrates
a configuration of main part in one embodiment of a magnetic disk
device (HDD: synonymous with magnetic recording and reproducing
device) according to the present invention.
[0030] FIG. 2 is a cross sectional view of a part of a head gimbal
assembly (HGA) in the magnetic disk device of FIG. 1.
[0031] FIG. 3 is a perspective view diagrammatically illustrating
the overall structure of a magnetic head.
[0032] FIG. 4 is a plan view (lamination direction) of a recording
head part of the magnetic head.
[0033] FIG. 5 is a cross sectional view in the direction of the
line indicated by arrow .alpha. shown in FIG. 4.
[0034] FIG. 6 is a cross sectional view in the direction of the
line indicated by arrow .beta. shown in FIG. 4.
[0035] FIG. 7 illustrates another embodiment of a wrap-around
structure.
[0036] FIG. 8 is a schematic perspective view diagrammatically
illustrating a state in which a first auxiliary coil and a second
auxiliary coil are inserted and arranged between a writing main
pole and the auxiliary pole that is a write shield film (the space
where a so-called magnetic gap film is formed).
[0037] FIGS. 9A, 9B, 9C and 9D are respective diagrams for
explaining a sequence of a state in which a circularly polarized
magnetic field is generated, and are views of the first auxiliary
coil and the second auxiliary coil from the air bearing surface
(ABS) side.
[0038] FIG. 10 is a plan view of the writing main pole and the
periphery thereof from the ABS side.
[0039] FIG. 11 is a schematic perspective view diagrammatically
illustrating a state in which three auxiliary coils are arranged in
the periphery of the writing main pole. The bottom side of the
drawing corresponds to the ABS.
[0040] FIG. 12 is a cross sectional view in the direction of the
line indicated by arrow I shown in FIG. 10.
[0041] FIG. 13 is a cross sectional view in the direction of the
line indicated by arrow II shown in FIG. 10.
[0042] FIGS. 14A, 14B, 14C, and 14D are respective diagrams for
explaining a sequence of a state in which a circularly polarized
magnetic field is generated, and are views of the first auxiliary
coil, the second auxiliary coil, and the third auxiliary coil from
the ABS side.
[0043] FIG. 15 is a schematic circuit diagram of a configuration in
which a phase difference in microwave currents applied respectively
to the first auxiliary coil and the second auxiliary coil is 90
degrees.
[0044] FIG. 16 is a schematic circuit diagram of a configuration in
which phase differences in microwave currents applied respectively
to the first auxiliary coil, the second auxiliary coil, and the
third auxiliary coil are 90 degrees.
DETAILED DESCRIPTION OF EMBODIMENTS
[0045] Hereafter, preferred embodiments to execute the present
invention will be explained in detail referring to the attached
drawings. In each drawing, elements which are configured the same
are indicated with the same reference numbers.
[0046] Dimensions of configuring elements and positional
relationships between the configuring elements are not always
illustrated precisely but illustrated arbitrarily to make the
drawings more easily understood.
[0047] An X-direction illustrated in FIG. 3 and thereafter
corresponds to a track width direction, and a size in the
X-direction may be referred to as "a width."A Y-direction
illustrated in the drawings corresponds to a depth direction of an
element. A side that is close to an ABS (a surface of a thin
magnetic head facing a recording medium) in the Y-direction shown
in FIG. 3 and thereafter may be referred to as "front-side," and an
opposite side with respect to the front-side may be referred to as
"rearward (depth side)."
[0048] A Z-direction illustrated in FIG. 3 and thereafter
corresponds to a direction where lamination films are layered to
configure the element, which is a so-called thickness direction.
The direction in which the lamination films are layered may be
referred to as "upward" or "upper side," and an opposite direction
may be referred to as "downward" or "down side."
[0049] FIG. 1 is a perspective view that schematically illustrates
a configuration of main part in one embodiment of the magnetic disk
device (HDD) (synonymous with magnetic recording reproducing
device) according to the present invention. FIG. 2 is a cross
sectional view illustrating a part of the tip end of the head
gimbal assembly (HGA) in the magnetic disk device shown in FIG.
1.
[0050] The magnetic disk device is illustrated in FIG. 1. Notation
210 indicates a plurality of magnetic disks that are rotated around
a rotational shaft 211a by a spindle motor 211. Notation 212
indicates an HGA for suitably opposing a slider base substrate 1
that includes a thin film magnetic head structure for writing and
reading data signals to and from magnetic disks 210, to the surface
of each magnetic disk 210. Notation 214 indicates an assembly
carriage device for positioning the slider base substrate 1 that
includes the thin film magnetic head structure on a track of the
magnetic disk 210.
[0051] The assembly carriage device 214 is mainly configured of a
carriage 216 that can angularly swing about a pivot bearing shaft
215, and a voice coil motor (VCM) 217, for example, that drives the
carriage 216 to perform the angular swing.
[0052] A base part of a plurality of drive arms 218 that are
stacked in the direction of the pivot bearing shaft 215 is attached
to the carriage 216. The HGA 212 is attached to the tip end part of
each of the drive arms 218. Furthermore, a single magnetic disk
210, a single drive arm 218, and a single HGA 212 may be provided
in the magnetic disk device.
[0053] The magnetic disk 210 is grounded via the spindle motor 211
and the rotational shaft 211a thereof.
[0054] In FIG. 1, notation 219 is a control circuit for controlling
the writing and reading operations of the thin film magnetic head
provided on the slider base substrate 1. A drive source and a
90-degree phase shifter may also be assembled herein for assistance
high frequency current applied to the auxiliary coil used in the
present invention. In addition, a control system may also be
assembled to enable current control or phase control. However, the
assembly location of these devices is not particularly restricted
to within the control circuit 219. The location for installation
may be appropriately selected according to the design
specification.
[0055] As illustrated in FIG. 2, the HGA 212 includes a slider base
substrate 1, a load beam 220 and flexure 221 made of a metallic
conductive material for supporting the slider base substrate 1, and
a variety of wiring members 222 that include wiring members for
applying the assistance high frequency current. The variety of the
wiring members 222 in the embodiment illustrated in FIG. 2 are
connected to terminal electrodes through wire bonding that use wire
223.
[0056] Moreover, a head element wiring member is also installed in
the HGA 212 for transmitting writing signals that are applied to
the writing head element of the thin film magnetic head formed on
the slider base substrate 1 and for retrieving reading output
voltages by applying constant current to the reading head
element.
[0057] The slider base substrate 1 is attached to one end of the
flexure 221 that has flexibility. A suspension for supporting the
slider base substrate 1 is configured by the load beam 220 that is
attached to the other end of the flexure 221.
[0058] (Description of Structure of Microwave Assisted Magnetic
Head of Present Invention)
[0059] The microwave assisted magnetic head of the present
invention is characterized by having a structure in which, as a
main part of the invention, at least two or more auxiliary coils
are arranged in the periphery of a writing main pole which is the
tip end part of a main pole film, and in which a circularly
polarized magnetic field is generated as an assistance magnetic
field by microwave current applied respectively to the two or more
auxiliary coils. Of course, the magnetic head also includes the
writing main pole, a writing coil for generating the writing
magnetic field to the writing main pole, and the like, which are
the fundamental structural members.
[0060] Hereinafter, in order to provide easily understandable
description of the configuration of the microwave assisted magnetic
head (maybe abbreviated hereinafter as simply "magnetic head") of
the present invention, descriptions will be provided separately to
explain the general structural members that form the basis of a
magnetic head, and to explain the configuration of the main part of
the present invention.
[0061] <Description of General Structural Members that Form
Basis of Magnetic Head>
[0062] First, with reference to FIGS. 3-7, the configuration of the
general structural members that form the basis of a magnetic head
is described. It is noted that descriptions of the structure of the
main part of the present invention that have minute linear body
structures are omitted due to restrictions in the size of the
paper.
[0063] FIG. 3 is a perspective view schematically illustrating the
overall structure of a magnetic head. FIG. 4 is a plan view of a
recording head part of a magnetic head. FIG. 5 is a cross sectional
view in the direction of the line indicated by arrow .alpha. shown
in FIG. 4. FIG. 6 is a cross sectional view in the direction of the
line indicated by arrow .beta. shown in FIG. 4.
[0064] The magnetic head, as illustrated in FIG. 3, includes a
slider base substrate 1 in an approximately rectangular structure.
The slider base substrate 1 includes an air bearing surface (ABS)
70 that is directly involved in the flying characteristics and a
recording head part 100B and a reproducing head part 100A at a side
end surface of the slider base substrate 1 that exists at the air
outflow side (trailing edge side) relative to the airflow direction
M (same as the substantive linear movement direction of the disk
shaped magnetic recording medium).
[0065] The details of the recording head part 100B and the
reproducing head part 100A are illustrated in FIGS. 4-6.
[0066] The magnetic head illustrated in FIGS. 3-6 is configured as
a composite type head capable of performing both recording and
reproducing of data. The magnetic head is configured on the slider
base substrate 1 in the following lamination order: an insulating
film 2, the reproducing head part 100A utilizing a magnetoresistive
effect (MR), a separation film 9, the recording head part 100B that
carries out a recording process with a perpendicular recording
system, and a nonmagnetic film 21 as an overcoat film.
[0067] (Description of the Reproducing Head Part 100A)
[0068] The reproducing head part 100A is configured by laminating
in order, for example, a lower lead shield film 3, a shield gap
film 4, and an upper lead shield film 30. A reproducing head
element (MR element 8) is embedded in the shield gap film 4 so as
to be exposed to the ABS 70 (see FIG. 5).
[0069] The lower lead shield film 3 and the upper lead shield film
30 magnetically separate the MR element 8 from the surroundings and
is configured to extend in the rearward direction from the ABS 70.
The lower lead shield film 3 is configured, for example, from a
magnetic material, such as nickel iron alloy (NiFe). The upper lead
shield film 30 is configured, for example, by laminating two upper
lead shield film portions 5 and 7 which sandwich a nonmagnetic film
6 therebetween. The upper lead shield film portions 5 and 7 are
configured, for example, from a magnetic material, such as nickel
iron alloy (NiFe). The nonmagnetic film 6 is configured, for
example, from a nonmagnetic material, such as ruthenium (Ru) or
alumina. In addition, the upper lead shield film 30 is not limited
to a three layer structure as described above, but may include a
structure made from a single layer configured, for example, from a
magnetic material, such as nickel iron alloy (NiFe).
[0070] The shield gap film 4 electrically separates the MR element
8 from the surroundings and is configured, for example, from a
nonmagnetic insulating material, such as alumina. The MR element 8
is configured from an element, such as a giant magnetoresistive
effect (GMR) element, a tunneling magnetoresistive effect (TMR)
element, or the like.
[0071] (Description of the Recording Head Part 100B)
[0072] The recording head part 100B includes a nonmagnetic film 11,
a pole film 50, a magnetic gap film 16 provided with a magnetic
coupling opening part (backgap 16BG), a coil film 18 embedded
within the insulating film 19, a magnetic film 60, a first write
shield film 15, and a second write shield film 17.
[0073] The nonmagnetic film 11 electrically and magnetically
separates an auxiliary pole film 10 from the surroundings and is
configured, for example, from a nonmagnetic material, such as
alumina.
[0074] The pole film 50 extends in the rearward direction from the
ABS 70 and includes the auxiliary pole film 10 and a main pole film
40. Depending on the design specification, the auxiliary pole film
10 and the main pole film 40 can be arranged vertically inverted (Z
direction). In addition, the coupling magnetic layer formed on the
magnetic coupling opening part (backgap 16BG) may also be referred
to as a coupling yoke 20a.
[0075] The auxiliary pole film 10 extends from a position away from
the ABS 70 to the backgap 16BG. The auxiliary pole film 10 is
arranged, for example, at the leading side relative to the main
pole film 40 and includes, as illustrated in FIG. 4, a rectangular
planar shape (width W2). The auxiliary pole film 10 may be arranged
to the trailing side of the main pole film 40 as described above.
In addition, the auxiliary coils 110, 120 and the like, which are
the main structures of the present invention having the
below-described minute linear body structure, are provided between
the main pole film 40 and the write shield film 17.
[0076] The main pole film 40 extends from the ABS 70 to the backgap
16BG. The main pole film 40 includes, for example, as illustrated
in FIG. 4, a narrow width writing main pole 40A that extends
rearward from the ABS 70, and a wide width body part 40B that
tapers from the rear side of the writing main pole 40A.
[0077] The writing main pole 40A is the substantive emitting part
of the magnetic flux (so-called pole film) and has a constant width
W1 that regulates the recording track width. The body part 40B is a
part that supplies the magnetic flux to the writing main pole 40A
and has a width W2 that is larger than the width W1. The width of
the body part 40B narrows gradually towards the writing main pole
40A. The position at which the width of the main pole film 40
begins to widen from the width W1 to the width W2 is called a flare
point FP.
[0078] The main pole film 40 is in an inverse trapezoidal shape in
which the end surface 40M on the side closer to the ABS 70 makes
the long edge positioned on the trailing side to be a top and the
short edge positioned on the leading side to be a bottom,
respectively. The top end edge of the trapezoidal shape is the
substantive recording location.
[0079] The magnetic gap film 16 is a gap for magnetically
separating the pole film 50 and the magnetic film 60 and is
configured, for example, from a nonmagnetic insulating material,
such as alumina or the like, or a nonmagnetic conductive material,
such as ruthenium or the like.
[0080] The recording coil film 18 generates a magnetic flux for
magnetic recording onto the medium and is configured, for example,
from a highly conductive material, such as copper (Cu) or the like.
The recording coil film 18, as illustrated in FIG. 4, includes a
spiral structure that is wound centrally around the backgap 16BG
(coupling yoke 20a).
[0081] The insulating film 19 electrically separates the recording
coil film 18 from the surroundings and is configured, for example,
from a nonmagnetic insulating material, such as a photoresist, a
spin-on-glass (SOG) or the like that exhibit flow properties when
applying heat. The frontmost end position of the insulating film 19
is the throat-height-zero position TP. The distance between the
throat-height-zero position TP and the ABS 70 is referred to as a
throat height TH. FIG. 4 illustrates a case in which the
throat-height-zero position TP matches the flare point FP.
[0082] The magnetic film 60 makes the gradient of the perpendicular
magnetic field steep by capturing the components spreading out from
the magnetic flux emitted from the pole film 50, while at the same
time, circulating the magnetic flux between the recording head 100B
and the recording medium by capturing the magnetic flux that
returns from the recording medium. As the magnetic film 60 extends
rearward from the ABS 70 on the trailing side of the pole film 50,
the magnetic film 60 is isolated from the pole film 50 by the
magnetic gap film 16 at the front side thereof and is coupled to
the pole film 50 through the backgap 16BG in the rear side. The end
surface 60M of the magnetic film 60 on the side near the ABS 70 is,
for example, in a rectangular shape with a width W3 that is larger
than the width W1 as illustrated in FIG. 4. The magnetic film 60
includes, for example, a second write shield film 17 and a return
yoke film 20 being made up of mutually separate bodies.
[0083] The first and second write shield films 15 and 17 mainly
provide a function for increasing the perpendicular magnetic field
gradient and are configured, for example, from a magnetic material
having a high saturation magnetic flux density, such as nickel iron
alloy, ferroalloy or the like. The first and second write shield
films 15 and 17 configure a so-called wrap-around structure. In
addition, these films, including the magnetic film 20, are referred
to as trailing shields.
[0084] In the wrap-around structure illustrated in FIG. 5, the
first write shield film 15 is adjunct, via the magnetic gap film
41, to both side surfaces of the ABS side of the writing main pole
40A that configures the main pole film 40. Accordingly, a side
shield film is formed on both sides of the writing main pole 40A by
the write shield film 15.
[0085] Further, the second write shield film 17 is adjunct, via the
magnetic gap film 16, to the top surface of the ABS side of the
writing main pole 40A. The second write shield film 17 is also
called a pedestal yoke, and the magnetic gap film 16 sandwiched
between the second write shield film 17 and the top surface of the
writing main pole 40A forms the writing gap.
[0086] The first and second write shield films 15 and 17 capture
the spreading components of the magnetic flux emitted from the pole
film 50 as a result of the arrangement described above to increase
the magnetic field gradient of the perpendicular magnetic field and
to narrow the recording width.
[0087] The second write shield film 17 extends in the rearward
direction from the ABS 70 while being adjunct to the magnetic gap
film 16, and is adjunct to the insulating film 19 at the rear end
thereof. In this manner, the write shield film 17 performs the role
of regulating the frontmost position (throat-height-zero position
TP) of the insulating film 19.
[0088] The return yoke film 20 performs the function of circulating
the magnetic flux and is configured, for example, from the magnetic
material similar to that for the write shield film 17. As
illustrated in FIG. 6, at the trailing side of the write shield
film 17, the return yoke film 20 extends from the ABS 70 to the
backgap 16BG via on the insulating film 19. The return yoke film 20
is coupled to the write shield film 17 in the front part thereof
and to the pole film 50 through the back gap 16BG in the rear part
thereof.
[0089] The nonmagnetic film 21 protects the magnetic head and is
configured, for example, from a nonmagnetic insulating material,
such as alumina or the like.
[0090] FIG. 7 illustrates another embodiment of the wrap-around
structure. In this embodiment, the periphery of the writing main
pole 40A is completely surrounded by the magnetic gap film 41 and
the upper magnetic gap film 16 that are formed continuously, and a
write shield film 15 that corresponds to the first and second write
shields (15 and 17) is arranged in the periphery thereof. In other
words, this embodiment provides a structure in which the writing
main pole 40A is embedded inside the write shield film 15. The
shield films positioned on both sides of the writing main pole 40A
function as side shield films, and the shield film positioned on
the upper side functions as the second write shield film
illustrated in FIGS. 3 to 6.
[0091] In addition, this wrap-around structure is not limited to
the above-described configuration. Various configurations can be
adopted. Furthermore, as understood from the explanation provided
below, application of the configuration of the main part of the
present invention is not limited only to the head including the
wrap-around structure.
[0092] <Description of Configuration of Main Part of Present
Invention>
[0093] The main part of the present invention is characterized by
including a structure in which at least two auxiliary coils are
arranged in the periphery of a writing main pole which is the tip
end part of a main pole film, and in which a circularly polarized
magnetic field is generated as an assistance magnetic field by
applying microwave currents respectively to the two or more
auxiliary coils with phase differences of the microwave currents
taken into account. In addition, the circularly polarized magnetic
field described in the present invention can be broadly interpreted
within the bounds to achieve the effect of the present invention,
and is a concept that also includes an elliptically polarized
magnetic field (for example, a ratio of the long axis to short axis
is within three).
[0094] Descriptions will be given below of two embodiments: 1) a
case in which two auxiliary coils are used and are arranged in a
recording gap, and 2) a case in which three auxiliary coils are
used and are arranged in the periphery of the writing main
pole.
First Embodiment
[0095] First, an embodiment in which two auxiliary coils are used
and are arranged in so-called recording gap spaces is described
with reference to FIGS. 8 to 9.
[0096] FIG. 8 is a schematic perspective view diagrammatically
illustrating a state in which a first auxiliary coil 110 and a
second auxiliary coil 120 are inserted and arranged between the
writing pole part (main pole) 40A and the auxiliary pole 17 that is
the write shield film (the space where the so-called magnetic gap
film is formed). The bottom side of the drawing corresponds to the
ABS 70. FIGS. 9A, 9B, 9C, and 9D are diagrams that view the first
auxiliary coil 110 and the second auxiliary coil 120 from the ABS
side. In addition, the shape of the member referred to as an
auxiliary coil within the present invention is not required to be
in a ring shape but may also be approximately in a U shape. This
structure can be easily understood by understanding the
configuration of the main part of the present invention as
described hereinafter.
[0097] As illustrated in FIG. 8, the first auxiliary coil 110
includes a first linear body part 110a that is linearly arranged
along the ABS, and first linear main bodies 110b, 110b that extend
in the Y direction (interior side (rearward)) from both end parts
of the first linear body part 110a. In the drawing, although the
first main bodies 110b, 110b are depicted only to the end surface
indicated by notation 111 due to the limitation of the sheet size,
in actuality the first main bodies 110b, 110b are not cut off at
this location. However, the first main bodies 110b, 110b extend
further in the Y direction and are connected to a microwave current
supply means.
[0098] The second auxiliary coil 120 includes a second linear body
part 120a that is linearly arranged along the ABS, and second
linear main bodies 120b, 120b that extend in the Y direction
(interior side (rearward)) from both end parts of the second linear
body part 120a. In the drawing, although the second linear main
bodies 120b, 120b are depicted only to the end surface indicated by
notation 121 due to with the restriction of the sheet size, in
actuality the second linear main bodies 120b, 120b are not cut off
at this location. However, the second linear main bodies 120b, 120b
extend further in the Y direction and are connected to a microwave
current supply means.
[0099] As illustrated in FIGS. 8 and 9, the first linear body part
110a of the first auxiliary coil 110 and the second linear body
part 120a of the second auxiliary coil 120 in the present invention
are orthogonally arranged in a crossing shape in a separated state.
The area in which the first auxiliary coil 110 and the second
auxiliary coil 120 illustrated in FIG. 8 exist is where the
so-called recording gap is formed, which is filled in with a
nonmagnetic material, in the so-called normal magnetic head. With
the present invention as well, although not illustrated in the
drawing, the peripheries around the first auxiliary coil 110 and
the second auxiliary coil 120 are also filled in with a nonmagnetic
material.
[0100] The wire diameter (thickness) of the first auxiliary coil
110 and the second auxiliary coil 120 is, for example, about 5 nm,
and the length of the first linear main body part 110a and the
second linear main body part 120a is about 20 nm. With such
dimensional specification, the first linear body part 110a and the
second linear body part 120a can be arranged with 5 nm spaces
provided on both sides there of even if, for example, the recording
gap space is about 30 nm.
[0101] As described above, the microwave current supply means for
applying microwave currents (high frequency current) is connected
to each of the first auxiliary coil 110 and the second auxiliary
coil 120. The microwave current supply means has, for example, a
phase shifter interposed at a middle step in the connection so that
a phase difference between the microwave currents applied
respectively to the first auxiliary coil 110 and the second
auxiliary coil 120 can be changed. In the present invention, a
configuration is provided so that the circularly polarized magnetic
field is generated as an assistance magnetic field from the ABS 70
by the microwave currents applied respectively to the first
auxiliary coil 110 and the second auxiliary coil 120. Therefore,
the microwave currents respectively applied to the first auxiliary
coil 110 and the second auxiliary coil 120 are configured so that
phase difference of 90 degrees is produced. The phase difference
may be either positive or negative. For example, as illustrated in
the schematic circuit diagram in FIG. 15, a high frequency current
drive source 165 is provided as a structural element of the
microwave current supply means. The current drive or the like by
the high frequency current drive source 165 is controlled based on,
for example, control signals from a hard disk drive (HDD)
controller 160. In addition, although the microwave current (high
frequency current) is respectively applied from the high frequency
current drive source 165 to the first auxiliary coil 110 and the
second auxiliary coil 120, a 90 degree phase shifter 171 is
preferably interposed in one of wire circuits (for example, on the
second auxiliary coil 120 side as illustrated in the drawing) to
change the phase difference by 90 degrees. In order to ensure the
phase difference, the wiring is preferably provided to configure
branch circuits from the same power source as illustrated in FIG.
15. Moreover, the microwave current supply means in the present
invention conceptually includes the means to change the phase
difference (for example, the 90 degree phase shifter).
[0102] The frequency of the applied microwave current is an ultra
high frequency (5 GHz to 40 GHz) of a microwave band that
corresponds to a ferromagnetic resonant frequency of the magnetic
microparticles that configure the magnetic recording layer of the
magnetic recording medium.
[0103] Accordingly, the state in which the circularly polarized
magnetic field is generated as an assistance magnetic field by
making phase differences of the microwave currents (high frequency
current) applied from the high frequency current drive source 165
respectively to the first auxiliary coil 110 and the second
auxiliary coil 120 to be 90 degrees is described with reference to
FIG. 9A, FIG. 9B, FIG. 9C and FIG. 9D.
[0104] FIG. 9A, FIG. 9B, FIG. 9C and FIG. 9D are diagrams that view
the first auxiliary coil 110 and the second auxiliary coil 120 from
the ABS 70 side. The first linear body part 110a of the first
auxiliary coil 110 and the second linear body part 120a of the
second auxiliary coil 120 is in a crossed formation in the shape of
a cross.
[0105] In these drawings, the phase of the second auxiliary coil
120 is greater than the phase of the first auxiliary coil 110 by 90
degrees. In other words, when a waveform that takes into account
the phase the high frequency current applied to the second
auxiliary coil 120 is sin (.omega.t+90), the waveform that takes
into account the phase of the high frequency current applied to the
first auxiliary coil 110 is expressed as sin (.omega.t).
[0106] FIG. 9A illustrates a state in which .omega.t=0. Therefore,
the high frequency current is applied only to the second auxiliary
coil 120 (120a) at the maximum amplitude value. In other words, the
high frequency current (i) is applied in the Z direction as
illustrated in the drawing to the second linear body part 120a of
the second auxiliary coil 120. As a result, a magnetic field
(indicated by dotted line arrows) is generated based on this
current according to the so-called right-handed screw rule. This
state is set, as a matter of convenience, as a starting point for
explaining the generation of a circularly polarized magnetic field.
In addition, the circle illustrated at the bottom of FIG. 9A is a
circle to assist in explaining the generation of the circularly
polarized magnetic field. Arrow B shown within the circle indicates
the direction of the magnetic field.
[0107] FIG. 9B, which shows the next step, illustrates a state in
which .omega.t=90 degrees. Therefore, the high frequency current is
applied only to the first auxiliary coil 110 (110a) at the maximum
amplitude value. In other words, the high frequency current (i) is
applied in the X direction as illustrated in the drawing to the
first linear body part 110a of the first auxiliary coil 110. As a
result, a magnetic field (indicated by dotted line arrows) is
generated based on this current according to the so-called
right-handed screw rule. In addition, the circle illustrated at the
bottom of FIG. 9B is a circle to assist in explaining the
generation of the circularly polarized magnetic field. The arrow B
shown within the circle indicates the direction of the magnetic
field. Between 0<.omega.t<90 degrees, a vector sum of the
magnetic fields resulted from the high frequency currents applied
respectively to the first linear body part 110a of the first
auxiliary coil 110 and the second linear body part 120a of the
second auxiliary coil 120, which produce the 90-degree phase
difference, results a 1/4 circular arc illustrated in the
drawing.
[0108] FIG. 9C, which shows the next step, illustrates a state in
which .omega.t=180 degrees. Therefore, the high frequency current
is applied only to the second auxiliary coil 120 (120a) at the
maximum amplitude value. In other words, the high frequency current
(i) is applied in the -Z direction as illustrated in the drawing to
the second linear body part 120a of the second auxiliary coil 120.
As a result, a magnetic field (indicated by dotted line arrows) is
generated based on this current according to the so-called
right-handed screw rule. In addition, the circle illustrated at the
bottom of FIG. 9C is a circle to assist in explaining the
generation of the circularly polarized magnetic field. The arrow B
shown within the circle indicates the direction of the magnetic
field. Between 90<.omega.t<180 degrees, the vector sum of the
magnetic fields resulted from the high frequency currents applied
respectively to the first linear body part 110a of the first
auxiliary coil 110 and the second linear body part 120a of the
second auxiliary coil 120, which produce the 90-degree phase
difference, results the 1/4 circular arc illustrated in the
drawing.
[0109] FIG. 9D, which shows the next step, illustrates a state in
which .omega.t=270 degrees. Therefore, the high frequency current
is applied only to the first auxiliary coil 110 (110a) at the
maximum amplitude value. In other words, the high frequency current
(i) is applied in the -X direction as illustrated in the drawing to
the first linear body part 110a of the first auxiliary coil 110. As
a result, a magnetic field (indicated by dotted line arrows) is
generated based on this current according to the so-called
right-handed screw rule. In addition, the circle illustrated at the
bottom of FIG. 9D is a circle to assist in explaining the
generation of the circularly polarized magnetic field. The arrow B
shown within the circle indicates the direction of the magnetic
field. Between 180<.omega.t<270 degrees is, the vector sum of
the magnetic fields resulted from the high frequency currents
applied respectively to the first linear body part 110a of the
first auxiliary coil 110 and the second linear body part 120a of
the second auxiliary coil 120, which produce the 90-degree phase
difference, results the 1/4 circular arc illustrated in the
drawing.
[0110] After the state illustrated in FIG. 9D, the process returns
to the state in FIG. 9A. Between 270<.omega.t<360 degrees is
(same as 0 degrees), the vector sum of the magnetic fields resulted
from the high frequency currents applied respectively to the first
linear body part 110a of the first auxiliary coil 110 and the
second linear body part 120a of the second auxiliary coil 120,
which produce the 90-degree phase difference, results the 1/4
circular arc.
[0111] It is understood that, through the states illustrated in
FIG. 9A, FIG. 9B, FIG. 9C and FIG. 9D in sequential order and by
returning to the state illustrated in FIG. 9A, the circularly
polarized magnetic field (example of clockwise rotation) is
generated from the ABS 70 as an assistance magnetic field. In
addition, a counterclockwise-rotation circularly polarized magnetic
field is also obviously possible by appropriately changing the
combination of mutual current directions.
Second Embodiment
[0112] Next, a second embodiment in which three auxiliary coils are
used is described with reference to FIGS. 10-13.
[0113] FIG. 10 is a plan view of the writing pole part (main pole)
40A and the periphery thereof from the ABS 70 side. FIG. 11 is a
schematic perspective view depicting a state in which three
auxiliary coils are arranged in the periphery of the writing pole
part (main pole) 40A, and the bottom side of the drawing
corresponds to the ABS 70. FIG. 12 is a cross sectional view in the
direction of the line indicated by arrow I shown in FIG. 10. FIG.
13 is a cross sectional view in the direction of the line indicated
by arrow II shown in FIG. 10.
[0114] As illustrated in FIG. 10 and FIG. 11, three auxiliary coils
130, 140 and 150 are arranged and formed so as to surround the
writing pole part (main pole) 40A.
[0115] As illustrated in FIG. 10, magnetic shield parts 15a, 15b
and 15c are formed so as to surround the writing pole part (main
pole) 40A positioned nearly in the center of the drawing. In other
words, a trailing side shield part 15a is arranged in the Z
direction (trailing side) of the writing pole part (main pole) 40A.
A first side shield part 15b is arranged in the X direction of the
writing pole part (main pole) 40A. A second side shield part 15c is
arranged in the -X direction of the writing pole part (main pole)
40A. These magnetic shield parts 15a, 15b and 15c form shield
(auxiliary) poles having the so-called wrap-around structure.
Notation 41 is a magnetic gap film formed from a nonmagnetic
material.
[0116] As illustrated in FIG. 10 and FIG. 11, the first auxiliary
coil 130 is arranged between the writing pole part 40A and the
trailing side shield part 15a. The second auxiliary coil 140 is
arranged between the writing pole part 40A and the first side
shield part 15b. The third auxiliary coil 150 is arranged between
the writing pole part 40A and the second side shield part 15c.
[0117] As illustrated in FIG. 11, the first auxiliary coil 130
includes a first linear body part 130a that is linearly arranged
along the ABS, and first linear main bodies 130b, 130b that extend
in the Y direction (interior side (rearward)) from both end parts
of the first linear body part 130a. In the drawing, although the
first linear main bodies 130b, 130b are depicted only to the end
surface indicated by notation 131 due to the limitation of the
sheet size, in actuality the first linear main bodies 130b, 130b
are not cut off at this location. However, the first linear main
bodies 130b, 130b extend further in the Y direction and are
connected to a microwave current supply means.
[0118] The second auxiliary coil 140 includes a second linear body
part 140a that is linearly arranged along the ABS, and second
linear main bodies 140b, 140b that extend in the Y direction
(interior side (rearward)) from both end parts of the second linear
body part 140a. In the drawing, although the second linear main
bodies 140b, 140b are depicted only to the end surface as indicated
by notation 141 due to the limitation of the sheet size, in
actuality the second linear main bodies 140b, 140b are not cut off
at this location. However, the second linear main bodies 140b, 140b
extend further in the Y direction and are connected to a microwave
current supply means.
[0119] The third auxiliary coil 150 includes a third linear body
part 150a that is linearly arranged along the ABS, and third linear
main bodies 150b, 150b that extend in the Y direction (interior
side (rearward)) from both end parts of the third linear body part
150a. In the drawing, although the third linear main bodies 150b,
150b are depicted only to the end surface as indicated by notation
151 due to the limitation of the sheet size, in actuality the third
linear main bodies 150b, 150b are not cut off but at this location.
However, the third linear main bodies 150b, 150b extend further in
the Y direction and are connected to a microwave current supply
means.
[0120] As illustrated in FIG. 10, the second linear body part 140a
and the third linear body part 150a are each arranged to have a
substantially orthogonal positional relationship to the first
linear body part 130a.
[0121] Here, the phrase "substantially orthogonal positional
relationship" indicates a range of 90.degree..+-.25.degree..
[0122] As illustrated in FIG. 10, FIG. 12 and FIG. 13, the area in
which the first auxiliary coil 130, the second auxiliary coil 140
and the third auxiliary coil 150 exist is a space filled in with a
nonmagnetic material.
[0123] As described above, the microwave current supply means for
applying microwave current is connected to each of the first
auxiliary coil 130, the second auxiliary coil 140, and the third
auxiliary coil 150.
[0124] The microwave current supply means includes, for example, a
phase shifter interposed at a middle step in the connection so that
phase differences between the microwave currents applied
respectively to the first auxiliary coil 130, the second auxiliary
coil 140 and the third auxiliary coil 150 can be changed. In the
present invention, a configuration is provided so that the
circularly polarized magnetic field is generated as an assistance
magnetic field from the ABS 70 by the microwave current applied
respectively to the first auxiliary coil 130, the second auxiliary
coil 140 and the third auxiliary coil 150. Therefore, the microwave
currents respectively applied to the second auxiliary coil 140 and
the third auxiliary coil 150 are configured so that the phase
differences relative to the first auxiliary coil 130 are produced
at 90 degrees. The phase differences may be either positive or
negative. For example, as illustrated in the schematic circuit
diagram of FIG. 16, a high frequency current drive source 165 is
prepared as the microwave current supply means. The current drive
or the like of the high frequency current drive source 165 is
controlled based on, for example, control signals from an HDD
controller 160. In addition, although the microwave current (high
frequency current) is respectively applied from the high frequency
current drive source 165 to the first auxiliary coil 130, the
second auxiliary coil 140 and the third auxiliary coil 150,
90-degree phase shifters 173 and 175 are preferably interposed in
two wire circuits (for example, on the second auxiliary coil 140
side and on the third auxiliary coil 150 side as illustrated in the
drawing) to change the phase differences of the microwave currents
respectively applied to the second auxiliary coil 140 and the third
auxiliary coil 150 by 90 degrees in relation to the first auxiliary
coil 130. In order to ensure the phase differences, the wiring is
preferably provided to configure with branch circuits from the same
power source as illustrated in FIG. 16.
[0125] Moreover, the microwave current supply means in the present
invention conceptually includes the means to change the phase
difference (for example, the 90-degree phase shifters).
[0126] Accordingly, the circularly polarized magnetic field is
generated as an assistance magnetic field by making the phase
differences of the microwave currents (high frequency currents)
applied from the high frequency current drive source 165
respectively to the second auxiliary coil 140 and the third
auxiliary coil 150 to be 90 degrees in relation to the microwave
current applied to the first auxiliary coil 130. This state is
explained with reference to FIG. 14A, FIG. 14B, FIG. 14C, and FIG.
14D.
[0127] FIG. 14A, FIG. 14B, FIG. 14C and FIG. 14D are diagrams that
view the first auxiliary coil 130, the second auxiliary coil 140
and the third auxiliary coil 150 from the ABS 70 side. The second
linear body part 140a of the second auxiliary coil 140 and the
third linear body part 150a of the third auxiliary coil 150 are
each arranged to have a substantially orthogonal positional
relationship to the first linear body part 130a of the first
auxiliary coil 130. As described above, the phrase "substantially
orthogonal positional relationship" indicates a range of
90.degree..+-.25.degree..
[0128] In these drawings, the phases of the second auxiliary coil
140 and the third auxiliary coil 150 are greater than the phase of
the first auxiliary coil 130 by 90 degrees. In other words, when a
waveform that takes into account the phase of the high frequency
currents applied to the second auxiliary coil 140 and the third
auxiliary coil 150 is sin (.omega.t+90), the waveform that takes
into account the phase of the high frequency current applied to the
first auxiliary coil 30 is expressed as sin (.omega.t).
[0129] FIG. 14A illustrates a state in which .omega.t=0. Therefore,
the high frequency currents are applied to the second auxiliary
coil 140 (140a) and the third auxiliary coil 150 (150a) at the
maximum amplitude value. In other words, the high frequency
currents (i) are applied in nearly the Z direction as illustrated
in the drawing to the second linear body part 140a of the second
auxiliary coil 140 and the third linear body part 150a of the third
auxiliary coil 150. As a result, a magnetic field (indicated by
dotted line arrows) is generated based on these currents according
to the so-called right-handed screw rule. This state is set, as a
matter of convenience, as a starting point for explaining the
generation of a circularly polarized magnetic field. In addition,
the circle illustrated at the bottom of FIG. 14A is a circle to
assist in explaining the generation of the circularly polarized
magnetic field. Arrow B shown within the circle indicates the
direction of the magnetic field.
[0130] FIG. 14B, which shows the next step, illustrates a state in
which .omega.t=90 degrees. Therefore, the high frequency current is
applied to the first auxiliary coil 130 (130a) at the maximum
amplitude value. In other words, the high frequency current (i) is
applied in the X direction as illustrated in the drawing to the
first linear body part 130a of the first auxiliary coil 130. As a
result, a magnetic field (indicated by dotted line arrows) is
generated based on this current according to the so-called
right-handed screw rule. The circle illustrated at the bottom of
FIG. 14B is a circle to assist in explaining the generation of the
circularly polarized magnetic field. The arrow B shown within the
circle indicates the direction of the magnetic field. Moreover,
between 0<.omega.t<90 degrees is, a vector sum of the
magnetic fields resulted from the high frequency current of applied
respectively to the first linear body part 130a of the first
auxiliary coil 130, the second linear body part 140a of the second
auxiliary coil 140 and the third linear body part 150a of the third
auxiliary coil 150, which produce the 90 degree phase difference,
results a 1/4 circular arc as illustrated.
[0131] FIG. 14C, which shows the next step, illustrates a state in
which .omega.t=180 degrees. Therefore, the high frequency currents
are applied to the second auxiliary coil 140 (140a) and the third
auxiliary coil 150 (150a) at the maximum amplitude value. In other
words, the high frequency currents (i) are applied in nearly the -Z
direction as illustrated in the drawing to the second linear body
part 140a of the second auxiliary coil 140 and the third linear
body part 150a of the third auxiliary coil 150. As a result, a
magnetic field (indicated by dotted line arrows) is generated based
on these currents according to the so-called right-handed screw
rule. The circle illustrated at the bottom of FIG. 14C is a circle
to assist in explaining the generation of the circularly polarized
magnetic field. The arrow B shown within the circle indicates the
direction of the magnetic field. Moreover, between
90<.omega.t<180 degrees is, the vector sum of the magnetic
fields resulted from the high frequency currents applied
respectively to the first linear body part 130a of the first
auxiliary coil 130, the second linear body part 140a of the second
auxiliary coil 140, and the third linear body part 150a of the
third auxiliary coil 150, which produce the 90-degree phase
difference, results the 1/4 circular arc as illustrated.
[0132] FIG. 14D, which shows the next step, illustrates a state in
which .omega.t=270 degrees. Therefore, the high frequency current
is applied to the first auxiliary coil 130 (130a) at the maximum
amplitude value. In other words, the high frequency current (i) is
applied in the -X direction as illustrated in the drawing to the
first linear body part 130a of the first auxiliary coil 130. As a
result, a magnetic field (indicated by dotted line arrows) is
generated based on this current according to the so-called
right-handed screw rule. The circle illustrated at the bottom of
FIG. 14D is a circle to assist in explaining the generation of
circularly polarized magnetic field. The arrow B shown within the
circle indicates the direction of the magnetic field. In addition,
between 180<.omega.t<270 degrees is, the vector sum of the
magnetic fields resulted from the high frequency currents applied
respectively to the first linear body part 130a of the first
auxiliary coil 130, the second linear body part 140a of the second
auxiliary coil 140, and the third linear body part 150a of the
third auxiliary coil 150, which produce the 90-degree phase
difference, results the 1/4 circular arc as illustrated.
[0133] After the state illustrated in FIG. 14D, the process returns
to the state in FIG. 14A. Moreover, between 180<.omega.t<360
degrees (same as 0 degrees), the vector sum of the magnetic fields
resulted from the high frequency currents applied respectively to
the first linear body part 130a of the first auxiliary coil 130,
the second linear body part 140a of the second auxiliary coil 140,
and the third linear body part 150a of the third auxiliary coil
150, which produce the 90-degree phase difference, results the 1/4
circular arc as illustrated.
[0134] It is understood that, through the states illustrated in
FIG. 14A, FIG. 14B, FIG. 14C and FIG. 14D are in sequential order
and by returning to the state illustrated in FIG. 9A, the
circularly polarized magnetic field (example of clockwise rotation)
is generated from the ABS 70 as an assistance magnetic field. In
addition, a counterclockwise-rotation circularly polarized magnetic
field is also obviously possible appropriately changing the
combination of mutual current directions.
[0135] Furthermore, the microwave assisted magnetic head according
to the present invention is not limited to the stricture of the
normal magnetic head in which the writing pole part 40A has a size
that fits within a single recording track. The microwave assisted
magnetic head according to the present invention may also include a
structure in which the writing pole part 40A has a size that
extends over several track pitches and may be used as a so-called
shingle magnetic recording magnetic head in which a head is
gradually shifted in the radial direction of the medium and
overlaps the writing of data.
[0136] Moreover, the microwave assisted magnetic head according to
the present invention may be formed by using thin film formation
technology or the like that utilizes a vacuum process.
DESCRIPTION OF THE EXPERIMENTAL EXAMPLE
[0137] The invention of the thin film magnetic head (microwave
assisted magnetic head) that provides a microwave assistance
function as described above can be realized as explained in detail
below.
Experimental Example
[0138] A microwave assisted magnetic head made from the
configuration illustrated in FIG. 8 is assumed. The space
(recording gap space) between the writing pole part (main pole) 40A
and the auxiliary pole 17, which is a shield, is configured to be
30 nm. The wire diameter (thickness) of the first auxiliary coil
110 and the second auxiliary coil 120 is configured to be 5 nm. The
length of the first linear body part 110a and the second linear
body part 120a is configured to be 20 nm. With such configurations,
the first linear body part 110a and the second linear body part
120a can be physically arranged in a cross shape as illustrated in
the drawing. In this case, the second auxiliary coil 120 may be
arranged with a 5-nm space on the writing pole part (main pole) 40A
side and a 5-nm space on the auxiliary pole 17 side that is a
shield.
[0139] Further, when the high frequency currents is respectively
applied to the first auxiliary coil 110 and the second auxiliary
coil 120, respectively, with a phase difference of 90 degrees, in
principle, a circularly polarized magnetic field is to be generated
as an assistance magnetic field from the ABS 70.
[0140] As described above, the microwave assisted magnetic head
according to the present invention is configured to include at
least two or more auxiliary coils that are arranged in a periphery
of the writing main pole; and microwave current supply means that
applies microwave currents to the at least two or more auxiliary
coils. Wherein, the at least two or more auxiliary coils
respectively include linear body parts linearly arranged on an air
bearing surface (ABS) side, two of the linear body parts of the at
least two or more auxiliary coils are arranged in a substantially
orthogonal positional relationship, and the microwave current
supply means is configured such that the microwave current supply
means changes a phase difference of the microwave currents applied
respectively to the at least two or more auxiliary coils.
Therefore, the microwave assisted magnetic head easily controls
microwave current (high frequency current) and can generate a
circularly polarized magnetic field with a high magnetization
inversion ratio as an assistance magnetic field.
* * * * *