U.S. patent application number 12/852775 was filed with the patent office on 2012-02-09 for microwave assisted magnetic head.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Takuya Adachi, Hiroshi Ikeda, Isamu Sato, Noboru YAMANAKA.
Application Number | 20120033534 12/852775 |
Document ID | / |
Family ID | 45508174 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120033534 |
Kind Code |
A1 |
YAMANAKA; Noboru ; et
al. |
February 9, 2012 |
MICROWAVE ASSISTED MAGNETIC HEAD
Abstract
A microwave assisted magnetic head is formed to include a main
pole magnetic layer including a main pole; a shielded magnetic
layer including a shielded pole; a recording coil that is formed to
generate a writing magnetic field from a tip of the main pole; and
a microwave radiation waveguide made of a conductive nonmagnetic
material that is disposed in a recording gap, the recording gap
being a gap between the main pole and the shielded pole. The main
pole magnetic layer and the shielded magnetic layer have an
intermediate connection part that connects the layers at a
depth-side, and an electrical insulation magnetic film is disposed
in the intermediate connection part, and the main pole and the
shielded pole are electrically connected with the microwave
radiation waveguide that is disposed in the recording gap, which is
the gap between the main pole and the shielded pole so that a
simple configuration, with a relatively easy and efficient
manufacturing process, is realized that overlaps AC magnetic fields
in an in-plane direction of a microwave band, which is the same as,
or close to, a ferromagnetic resonant frequency of a medium
recording layer.
Inventors: |
YAMANAKA; Noboru; (Tokyo,
JP) ; Adachi; Takuya; (Tokyo, JP) ; Sato;
Isamu; (Tokyo, JP) ; Ikeda; Hiroshi; (Tokyo,
JP) |
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
45508174 |
Appl. No.: |
12/852775 |
Filed: |
August 9, 2010 |
Current U.S.
Class: |
369/13.24 ;
G9B/11 |
Current CPC
Class: |
G11B 2005/0024 20130101;
G11B 5/314 20130101; G11B 5/1278 20130101 |
Class at
Publication: |
369/13.24 ;
G9B/11 |
International
Class: |
G11B 11/00 20060101
G11B011/00 |
Claims
1. A microwave assisted magnetic head, comprising: a main pole
magnetic layer including a main pole; a shielded magnetic layer
including a shielded pole; a recording coil that is formed to
generate a writing magnetic field from a tip of the main pole; and
a microwave radiation waveguide made of a conductive nonmagnetic
material that is disposed in a recording gap, the recording gap
being a gap between the main pole and the shielded pole, wherein
the main pole magnetic layer and the shielded magnetic layer have
an intermediate connection part that connects the layers at a
depth-side, and an electrical insulation magnetic film is disposed
in the intermediate connection part, and the main pole and the
shielded pole are electrically connected with the microwave
radiation waveguide that is disposed in the recording gap, which is
the gap between the main pole and the shielded pole.
2. The microwave assisted magnetic head according to claim 1,
wherein a microwave oscillator is connected to an electric circuit
that is formed by the main pole magnetic layer, the microwave
radiation waveguide, and the shielded magnetic layer, and the
connected microwave oscillator is configured to radiate a microwave
band resonant magnetic field having either a ferromagnetic resonant
frequency or an adjacent frequency of a magnetic recording medium,
which is subjected to recording, by applying a microwave exciting
current.
3. The microwave assisted magnetic head according to claim 1,
wherein a microwave oscillator is connected to an electric circuit
that is formed by the main pole magnetic layer, the microwave
radiation waveguide, and the shielded magnetic layer, and the
connected microwave oscillator is configured to generate a current
by applying a microwave exciting current, and to make the current
flow in a direction perpendicular to a film surface of the
waveguide.
4. The microwave assisted magnetic head according to claim 1,
wherein the microwave radiation waveguide is made of Ru, Ti, or
Ta.
5. The microwave assisted magnetic head according to claim 1,
wherein the recording gap, which is the gap between the main pole
and the shielded pole, is configured with a gap formed between an
edge of the main pole at a trailing side and the shielded pole.
6. The microwave assisted magnetic head according to claim 1,
wherein the electrical insulation magnetic film is ferrite formed
of ferromagnetic oxide.
7. The microwave assisted magnetic head according to claim 2,
wherein the microwave oscillator includes an integrated circuit
(IC) or a microwave oscillation element supplying the microwave
exciting current.
8. The microwave assisted magnetic head according to claim 1,
wherein the shielded magnetic layer is a non-wrap-around shield
type with which only the shielded pole is provided, the shielded
pole being positioned facing the main pole when seen from an air
hearing surface (ABS), which is a surface facing the magnetic
recording medium.
9. The microwave assisted magnetic head according to claim 1,
wherein the shielded magnetic layer is a wrap-around shield type
that is formed as a comprehensive shielded pole surrounding the
main pole via a partially formed nonmagnetic part when seen from
the ABS, which is a surface facing the magnetic recording
medium.
10. The microwave assisted magnetic head according to claim 1,
wherein the recording gap, which is the gap between the main pole
and the shielded pole, includes an inclined part of which an
inclining angle .theta. is 20-40.degree. toward the depth-side from
the ABS when seen in a vertical cross section, and the microwave
radiation waveguide is disposed along the inclined recording
gap.
11. A head gimbal assembly, comprising: a slider that includes the
thin film magnetic head according to claim 1 and that is positioned
facing a recording medium; and a suspension that elastically
supports the slider.
12. A magnetic disk device, comprising: the slider that includes
the thin film magnetic head according to claim 1 and that is
positioned facing a recording medium; and a positioning device that
supports and positions the slider with respect to the recording
device.
Description
BACKGROUND
[0001] 1. Field of the Invention
[0002] The present invention relates to microwave assisted magnetic
heads and magnetic disk devices providing a microwave radiation
waveguide, which generate an alternating current (AC) magnetic
field of a microwave band, to assist in writing data signals on
magnetic recording media having a large coercive force to stabilize
the magnetization.
[0003] 2. Description of Conventional Art
[0004] In association with an advance of high density recording,
bit cells for recording digital information on magnetic recording
media are miniaturized. As a result, since signals detected by a
reproducing element of a magnetic head fluctuate due to so-called
thermal fluctuation, a signal-noise ratio (S/N) may be deteriorated
or the signal may be lost in the worst case.
[0005] For a magnetic recording medium of a perpendicular recording
system, which is utilized in practice in recent years, an increase
in perpendicular magnetic anisotropy energy Ku of a recording film
is effective to solve the above-described problem. A stability
thermal stability coefficient that corresponds to the thermal
fluctuation is given by KuV/kBT. Herein, Ku is perpendicular
magnetic anisotropy energy, V is a volume of one magnetic
microparticle, kB is the Boltzmann constant, and T is the absolute
temperature.
[0006] According to the so-called Stoner-Wohlfarth model,
anisotropy energy Hk and coercive force He of the recording film
are indicated by a formula below. In accordance with the increase
in Ku, the coercive force He also increases (additionally, Hk>Hc
for normal recording films).
H=Hc=2Ku/Ms
[0007] Herein, Ms is a saturation magnetization of the recording
film.
[0008] For a reversal of magnetization of the recording film
corresponding to a desired data sequence, it is necessary to apply
a recording magnetic field that is steep and approximately around
Hk at maximum. For magnetic disk devices (or hard disk drive, HDD),
which are utilized in practice in recent years because of the
perpendicular recording system, a recording element with a
so-called single magnetic pole is utilized. A recording magnetic
field is applied, which is perpendicular to a recording film from a
surface of an air bearing surface (ABS).
[0009] An intensity of a perpendicular recording magnetic field is
proportional to a saturation magnetic flux density Bs of a soft
magnetic material forming the single magnetic pole. Therefore,
materials having a saturation magnetic flux density Bs as high as
possible are developed and utilized in practice.
[0010] However, according to the so-called Slater-Pauling curve,
Bs=2.4 T (tesla) is a limit of the saturation magnetic flux density
Bs for practical use, and currently it is approaching the limit for
practical use.
[0011] A thickness and/or a width of a current single magnetic pole
is approximately 100-200 nm. In order to increase a recording
density, further reduction of the thickness and/or width is
required, and the perpendicular magnetic field generated with such
a minute magnetic pole tends to be reduced.
[0012] For these reasons, it can be said that the recording ability
of the ordinary data writing element is approaching the limit, and
that difficulties are faced to achieve the high density
recording.
[0013] Therefore, a so-called thermal assisted magnetic recording
(TAMR) has been proposed. With the TAMR, the recording film is
irradiated with laser light etc., the temperature of the recording
film is increased, and signals are recorded in a situation where
the coercive force of the recording film is lowered.
[0014] However, there are the following problems even for the TAMR.
(1) A magnetic head providing a magnetic element and an optical
element is required so that the configuration thereof is extremely
complex and expensive. (2) It is required to develop a recording
film which has a coercive force with a highly sensitive temperature
characteristic. (3) Due to a thermal demagnetization during a
recording process, adjacent track erasures may occur and/or a
recording condition becomes unstable.
[0015] On the other hand, in order to largely reduce perpendicular
recording magnetic fields that are necessary for magnetization
reversal, it is considered to overlap AC magnetic fields in an
in-plane direction with a microwave band on a perpendicular
recording magnetic field generated from a tip of a main pole for
exciting the magnetization reversal. The AC magnetic fields are the
same as, or close to, a ferromagnetic resonant frequency of a
medium recording layer. Such an assisted recording method is
referred to as microwave assisted magnetic recording (MAMR), and
its efficiencies are experimentally verified.
[0016] With respect to the MAMR, two methods have been mainly
proposed. One is a method that generates a microwave magnetic field
in the in-plane direction by forming a spin torque oscillator (STO)
formed of a multilayered magnetic thin film in a gap (write gap)
between a main pole (or write pole) of the magnetic head and an
auxiliary magnetic pole that is a write shield, and by driving a
bias electric current to oscillate the STO, as discussed in
Reference 1 (J. Zhu et al.; IEEE Transaction on Magnetics, Vol. 44,
No. 1, p. 125) (this may be called a STO type).
[0017] The other is a method that generates an in-plane AC magnetic
field by providing a secondary coil in, or adjacent to, the write
gap between the main pole and the auxiliary magnetic pole of the
magnetic head and by driving an AC of a microwave band to the
secondary coil, as discussed in Reference 2 (JP Patent Laid-open
Publication 2007-299460) (this may be called a coplanar waveguide
(CPW) type).
[0018] The STO type has a complex process because an STO element
configured of multilayered films is embedded in the write gap that
is in a scale of approximately 30 nm, and an oscillation frequency
and power of the type has a limit due to a configuration of the STO
element and an applied bias. Therefore, it is assumed that the STO
type lacks versatility for all types of the perpendicular magnetic
recording medium.
[0019] With the above described CPW type, which is different from
the STO type, its frequency and power are arbitrarily set by a high
frequency oscillation source mounted outside. However, it is
required to form a coil conductor in the write gap and to embed a
periphery thereof with insulators, so that there are structural and
dimensional limitations and the process is complex.
[0020] The present invention is conceived corresponding to the
current situation. One of objectives of the present invention is to
provide a microwave assisted magnetic head that has a novel
configuration, having a simple configuration, with a relatively
easy and efficient manufacturing process, and that overlaps AC
magnetic fields in an in-plane direction of a microwave band, which
is the same as, or close to, a ferromagnetic resonant frequency of
a medium recording layer.
SUMMARY
[0021] In order to solve the above problems, a microwave assisted
magnetic head of the present application includes a main pole
magnetic layer including a main pole; a shielded magnetic layer
including a shielded pole; a recording coil that is formed to
generate a writing magnetic field from a tip of the main pole; and
a microwave radiation waveguide made of a conductive nonmagnetic
material that is disposed in a recording gap, the recording gap
being a gap between the main pole and the shielded pole, wherein
the main pole magnetic layer and the shielded magnetic layer have
an intermediate connection part that connects the layers at a
depth-side, and an electrical insulation magnetic film is disposed
in the intermediate connection part, and the main pole and the
shielded pole are electrically connected with the microwave
radiation waveguide that is disposed in the recording gap, which is
the gap between the main pole and the shielded pole.
[0022] In a preferred embodiment of the present invention, a
microwave oscillator is connected to an electric circuit that is
formed by the main pole magnetic layer, the microwave radiation
waveguide, and the shielded magnetic layer, and the connected
microwave oscillator is configured to radiate a microwave band
resonant magnetic field having either a ferromagnetic resonant
frequency or an adjacent frequency of a magnetic recording medium,
which is subjected to recording, by applying a microwave exciting
current.
[0023] In a preferred embodiment of the present invention, a
microwave oscillator is connected to an electric circuit that is
formed by the main pole magnetic layer, the microwave radiation
waveguide, and the shielded magnetic layer, and the connected
microwave oscillator is configured to generate a current by
applying a microwave exciting current, and to make the current flow
in a direction perpendicular to a film surface of the
waveguide.
[0024] In a preferred embodiment of the present invention, the
microwave radiation waveguide is made of Ru, Ti, or Ta.
[0025] In a preferred embodiment of the present invention, the
recording gap, which is the gap between the main pole and the
shielded pole, is configured with a gap formed between an edge of
the main pole at a trailing side and the shielded pole.
[0026] In a preferred embodiment of the present invention, the
electrical insulation magnetic film is ferrite formed of
ferromagnetic oxide.
[0027] In a preferred embodiment of the present invention, the
microwave oscillator includes an integrated circuit (IC) or a
microwave oscillation element supplying the microwave exciting
current.
[0028] In a preferred embodiment of the present invention, the
shielded magnetic layer is a non-wrap-around shield type with which
only the shielded pole is provided, the shielded pole being
positioned facing the main pole when seen from an air bearing
surface (ABS), which is a surface facing the magnetic recording
medium.
[0029] In a preferred embodiment of the present invention, the
shielded magnetic layer is a wrap-around shield type that is formed
as a comprehensive shielded pole surrounding the main pole via a
partially formed nonmagnetic part when seen from the ABS, which is
a surface facing the magnetic recording medium.
[0030] In a preferred embodiment of the present invention, the
recording gap, which is the gap between the main pole and the
shielded pole, includes an inclined part of which an inclining
angle .theta. is 20-40.degree. toward the depth-side from the ABS
when seen in a vertical cross section, and
[0031] the microwave radiation waveguide is disposed along the
inclined recording gap.
[0032] A head gimbal assembly of the present invention includes a
slider that includes the thin film magnetic head and that is
positioned facing a recording medium; and a suspension that
elastically supports the slider.
[0033] A magnetic disk device of the present invention includes the
slider that includes the thin film magnetic head and that is
positioned facing a recording medium; and a positioning device that
supports and positions the slider with respect to the recording
device.
BRIEF DESCRIPTION OF DRAWINGS
[0034] FIG. 1 illustrates a configuration of a microwave assisted
magnetic head (thin film magnetic head) according to one preferred
embodiment of the present invention. FIG. 1 is a cross-sectional
drawing (Y-Z cross-sectional drawing) illustrating a cross section
that is perpendicular to an air bearing surface (ABS) and a
substrate of the thin film magnetic head, and further illustrating
a magnetic recording medium that is subjected to recording.
[0035] FIG. 2 is a view seen from an arrow of .beta.1-.beta.1 of
FIG. 1, and is the view of the ABS of the microwave assisted
magnetic head according to one preferred embodiment of the present
invention.
[0036] FIG. 3A illustrates one aspect of a planar shape (X-Y
surface (additionally, when a waveguide has an inclined surface,
the plane is along an incline thereof)) of the microwave radiation
waveguide positioned in a recording gap that is between a main pole
and a shielded pole. FIG. 3A corresponds to a view seen from an
arrow of .alpha.1-.alpha.1 of FIG. 2.
[0037] FIG. 3B illustrates one aspect of the planar shape (X-Y
surface (additionally, when a waveguide has the inclined surface,
the plane is along the incline)) of the microwave radiation
waveguide positioned in the recording gap that is between the main
pole and the shielded pole. FIG. 313 corresponds to the view seen
from the arrow of .alpha.1-.alpha.1 of FIG. 2.
[0038] FIG. 3C illustrates one aspect of the planar shape (X-Y
surface (additionally, when the waveguide has the inclined surface,
the plane is along the incline)) of the microwave radiation
waveguide positioned in the recording gap that is between the main
pole and the shielded pole. FIG. 3C corresponds to the view seen
from the arrow of .alpha.1-.alpha.1 of FIG. 2.
[0039] FIG. 4 is a view of the ABS of the microwave radiation
waveguide positioned in the recording gap that is between the main
pole and the shielded pole.
[0040] FIG. 5A illustrates one aspect of the planar shape (X-Y
surface) of the microwave radiation waveguide positioned in the
recording gap that is between the main pole and the shielded pole.
FIG. 5A corresponds to the view seen from the arrow of
.alpha.2-.alpha.2 of FIG. 4.
[0041] FIG. 5B illustrates one aspect of the planar shape (X-Y
surface (additionally, when the waveguide has the inclined surface,
the plane is along the incline)) of the microwave radiation
waveguide positioned in the recording gap that is between the main
pole and the shielded pole. FIG. 5B corresponds to the view seen
from the arrow of .alpha.2-.alpha.2 of FIG. 4.
[0042] FIG. 6 illustrates a configuration of a microwave assisted
magnetic head (a thin film magnetic head of a wrap-around shield
type) according to one preferable embodiment of the present
invention. FIG. 6 is a cross-sectional view (Y-Z cross-sectional
view) illustrating a cross section perpendicular to the ABS and the
substrate of the thin film magnetic head, and further illustrating
the magnetic recording medium that is subjected to recording.
[0043] FIG. 7 is a view seen from an arrow .beta.2-.beta.2 of FIG.
6 and illustrates the ABS of the microwave assisted magnetic head
according to one preferable embodiment of the present
invention.
[0044] FIG. 8A is a view seen from the arrow .beta.2-.beta.2 of
FIG. 6. FIG. 8A illustrates especially a position of the microwave
radiation waveguide between the main pole and the shielded pole
(the wrap-around shield type) and the ABS of the microwave assisted
magnetic head.
[0045] FIG. 8B is a view seen from the arrow .beta.2-.beta.2 of
FIG. 6. FIG. 8B illustrates especially the position of the
microwave radiation waveguide between the main pole and the
shielded pole (the wrap-around shield type), and is a view of the
ABS of the microwave assisted magnetic head.
[0046] FIG. 9 is a perspective view illustrating a slider included
in a head gimbal assembly according to one preferable embodiment of
the present invention.
[0047] FIG. 10 is a perspective view of a head arm assembly
including the head gimbal assembly according to one preferable
embodiment of the present invention,
[0048] FIG. 11 is an explanatory view illustrating a main part of a
magnetic disk device of one preferable embodiment of the present
invention.
[0049] FIG. 12 is a plan view of the magnetic disk device of one
preferable embodiment of the present invention.
[0050] FIG. 13 illustrates a modeling state of a magnetic field
distribution indicated as a protruded wedge shape in a -Y direction
directed to the facing magnetic recording medium) when generated
from the microwave radiation waveguide of a sample of an
example.
[0051] FIG. 14 is a graph illustrating a magnetic field
distribution in a thickness direction (a Z-direction which is the
same as a trail direction) of the microwave radiation waveguide of
the sample of the example.
[0052] FIG. 15 is a graph illustrating a magnetic field
distribution in a width direction (a X-direction which is the same
as an off-track direction) of the microwave radiation waveguide of
the sample of the example.
[0053] FIG. 16 is a graph illustrating a magnetic field
distribution of the width direction (the X-direction which is the
same as the off-track direction) of the microwave radiation
waveguide of a sample of another example.
[0054] FIG. 17 corresponds to FIG. 1 and is a partially enlarged
view clearly illustrating especially a state where the microwave
radiation waveguide 18 is disposed in the recording gap between the
main pole 15 and the shielded pole 25.
[0055] FIG. 18 corresponds to FIG. 1 and is a partially enlarged
view clearly illustrating especially a state where the microwave
radiation waveguide 18 is disposed in the recording gap between the
main pole 15 and the shielded pole 25.
DETAILED DESCRIPTION OF EMBODIMENTS
[0056] 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. 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.
[0057] An X-direction illustrated in the drawings corresponds to a
track width direction, and a size in the X-direction may be
referred to as "a width."
[0058] 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 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)."
[0059] A Z-direction illustrated in the drawings 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."
[0060] Prior to a description of a configuration of a main part of
the present invention, an entire configuration of a microwave
assisted magnetic head (the thin film magnetic head) of the present
invention will be explained.
(Description of Entire Configuration of Microwave Assisted Magnetic
Head (Thin Film Magnetic Head))
[0061] FIG. 1 illustrates a cross section (a cross section of Y-Z
surface) of the thin film magnetic head parallel to the ABS.
[0062] A thin film magnetic head 100 illustrated in FIG. 1 is
mounted to a magnetic recording device such as, for example, a hard
disk drive and is utilized to perform a magnetic process on a
magnetic recording medium 10, such as a hard disk, that moves
toward a medium traveling direction M.
[0063] The thin film magnetic head 100 illustrated in the drawing
as an example is a so-called composite-type head, which performs
both a recording process and a reproducing process as the magnetic
process. As illustrated in FIG. 1, the thin film magnetic head 100
is configured with a structure where a magnetic head part 101
having both of the above-described process functions is formed
above a slider substrate 1 made of a ceramic material such as, for
example, AlTiC (Al.sub.2O.sub.3.TiC) through an insulation layer 2
such as alumina.
[0064] The magnetic head part 101 is configured with a reproducing
head part 100A and a recording head part 100B, and the reproducing
head part 100A and the recording head part 100B are layered in the
Z-direction in this order. The reproducing head part 100A performs,
for example, the reproduction of recorded magnetic information
using a magneto-resistive (MR) effect. The recording head part 100B
performs, for example, the recording process of a perpendicular
recording system.
[0065] Hereafter, further detailed description will be given.
[0066] In the reproducing head part 100A, a first shield layer 3
and a second shield layer 5 are planar layers, which are
respectively formed to be approximately parallel to an upper side
surface of the slider substrate 1. The first and second shield
layers 3 and 5 respectively form a part of the ABS 70.
[0067] A magnetoresistive effect (MR) element 8 is sandwiched
between the first shield layer 3 and the second shield layer 5, and
forms a part of the ABS 70 facing the surface of the medium.
[0068] The first shield layer 3 and the second shield layer 5 are
formed by, for example, a frame plating method, a pattern plating
method, and the like.
[0069] The MR element 8 is a lamination film formed by laminating
preferred materials in the Z-direction as well as, for example,
forming a TMR element or a GMR element, and forms a part of the ABS
70 facing the surface of the medium.
[0070] It is desired that the MR element 8 is a lamination film of
a current perpendicular to plane (CPP) type that applies a sense
current in a direction perpendicular to a lamination surface
thereof.
[0071] Generally, the first shield layer 3 and the second shield
layer 5 are designed to function as electrodes. As illustrated in
FIG. 1, an electric circuit 7 for applying reader bias (which means
the same as applying the sense current) is incorporated in the
first shield layer 3 and the second shield layer 5. As a result,
the sense current flows in the direction perpendicular to the
lamination surface of the MR element 8.
[0072] Although not illustrated in the drawings, an interelement
shield layer that is made of the same material as the second shield
layer 5 can be further disposed between the second shield layer 5
and the recording head part 100B. This is to prevent an exogenous
noise during reading by blocking the magnetic field generated from
the recording head part 100B.
[0073] A bucking coil part (not illustrated) may be formed between
the interelement shield layer formed as a preferred embodiment and
the recording head part 100B. The bucking coil part generates a
magnetic flux that negates a magnetic flux loop that is generated
from the recording head part 100B and that passes through the
magnetic pole layers (usually, the first and second shield layers 3
and 5) on and under the MR element 8. The bucking coil part
suppresses unnecessary writing to the magnetic disk and a wide area
adjacent track erasure (WATE) phenomenon, which is an erasing
operation.
[0074] An insulation layer 4 made of alumina or the like is formed
between the first shield layer 3 and the second shield layer 5, on
the side of the MR element 8 opposite to the ABS 70. Although not
illustrated in the drawings, a rearward portion, which is on the
opposite side from the ABS 70 of the first and second shield layers
3 and 5, is formed with an insulation layer of alumina or the
like.
[0075] The recording head part 100B is configured for a
perpendicular magnetic recording.
[0076] As illustrated in FIGS. 1 and 2, the recording head part
100B is configured as a microwave assisted magnetic head with a
main pole magnetic layer 16 including a main pole 15, a shielded
magnetic layer 26 including a shielded pole 25, recording coils 23
that generates a recording magnetic field from a tip of the main
pole 15, a microwave radiation waveguide 18 that is inserted in a
recording gap, which is a gap between the main pole 15 and the
shielded pole 25.
[0077] As illustrated in FIG. 1, a writing circuit 27 for
generating signals from a write driver to the recording coils 23 is
formed so as to generate the recording magnetic field from the tip
of the main pole 15 by applying a writing current to the recording
coils 23.
[0078] The main pole magnetic layer 16 including the main pole 15
is configured as a magnetic guide for guiding a magnetic flux
induced by a layer of the recording coils 23 to the recording layer
of the magnetic recording medium 10, which is to be written, as the
magnetic flux is being focused. Herein, the main pole 15 is a
portion of the main pole magnetic layer 16 that is in the vicinity
of the ABS. At the edge part on the side of the ABS 70, the main
pole 15 has, compared with the other portion, an extremely small
width in the track width direction (a direction along the
X-direction in FIG. 1) and an extremely small thickness in a
lamination direction (a direction along the Z-direction of FIG. 1).
As a result, the main pole 15 generates a minute and strong writing
magnetic field that corresponds to the high recording density.
[0079] As illustrated in FIGS. 1 and 2, the microwave radiation
waveguide 18 is disposed at the position of the recording gap,
which is the gap between the main pole 15 and the shielded pole 25.
Due to the intervening microwave radiation waveguide 18, the main
pole 15 and the shielded pole 25 are electrically connected.
Furthermore, these are also magnetically connected. This
configuration is a connecting configuration, which is not seen in
the conventional device. By adopting such a configuration, a
manufacturing process will be extremely simplified and easy.
[0080] When seen from the Y-Z vertical cross sectional surface as
illustrated in the partially enlarged view of FIG. 17, it is
desired that the recording gap, which is the gap between the main
pole 15 and the shielded pole 25, has an inclined part where an
inclining angle .theta. is 20-40.degree. toward the depth-side from
the ABS with respect to the Y-direction that is a depth direction.
The microwave radiation waveguide 18 is disposed along the inclined
recording gap. Therefore, the microwave radiation waveguide 18 also
has an inclined part where the inclining angle .theta. is
20-40.degree.. With the taper recording gap, a magnetic field
intensity and/or a magnetic field gradient are improved.
[0081] As illustrated in FIG. 18, even when the inclined angle
.theta. is zero and the microwave radiation waveguide 18 has no
inclined part, the objectives of the present invention are
sufficiently achieved. The objectives are "to provide a microwave
assisted magnetic head that has a novel configuration, having a
simple configuration, with a relatively easy and efficient
manufacturing process, and that overlaps AC magnetic fields in an
in-plane direction of a microwave band, which is the same as, or
close to, ferromagnetic resonant frequency of a medium recording
layer."
[0082] The microwave radiation waveguide 18 is desirably made of
Ru, Ti or Ta. The waveguide 18 is formed by, for example, a
sputtering method, CVD method or the like. A detailed embodiment
will be described below.
[0083] As illustrated in FIG. 1, the main pole magnetic layer 16
and a shielded magnetic layer 26 have an intermediate connection
part G at the depth-side (the Y-direction). At the intermediate
connection part G, an electrical insulation magnetic film 9 is
disposed that connects the main pole magnetic layer 16 with the
shielded magnetic layer 26.
[0084] The electrical insulation magnetic film 9 provides that
members connecting via the film 9 are magnetically connected, but
are not electrically connected because of electrical insulation.
Therefore, a magnetic path is formed with the main pole magnetic
layer 16 and the shielded magnetic layer 26 through the electrical
insulation magnetic film 9, but the electric circuit is not formed
with the main pole magnetic layer 16 and the shielded magnetic
layer 26 through the electrical insulation magnetic film 9.
However, there is no problem about the electric circuit not being
formed through the electrical insulation magnetic film 9.
Therefore, a microwave oscillator 17 is connected from the outside
to the electric circuit that does not go through the electrical
insulation magnetic film 9 and that is formed with the main pole
magnetic layer 16, the microwave radiation waveguide 18, and the
shielded magnetic layer 26.
[0085] By applying a microwave exciting current from the connected
microwave oscillator 17, a microwave band resonant magnetic field
having the ferromagnetic resonant frequency of the magnetic
recording medium that is subjected to recording or having an
adjacent frequency thereof is radiated from the microwave radiation
waveguide 18. The outside microwave oscillator 17 is a device that
provides a known microwave oscillator that oscillates a band of
tens of GHz or more, which is different from a frequency used for
recording and reproducing data. The microwave oscillator is
configured to provide an IC or a microwave oscillation element
supplying the microwave exciting current.
[0086] The electrical insulation magnetic film 9 is desirably made
of a magnetic material having an electrical insulation
characteristic such as a ferromagnetic oxide such as, for example,
ferrite. A direction to apply the microwave exciting current at the
ABS is the lamination direction of the main pole 15, the microwave
radiation waveguide 18 and the shielded pole 25 (the
Z-direction).
[0087] The shielded pole 25, which is at the edge part on the side
of the ABS 70 where the shielded magnetic layer 26 is magnetically
connected to the main pole magnetic layer 16, forms a so-called
trailing shield part where a cross section of the layer is larger
than other parts of the shielded magnetic layer 26. By disposing
such a shielded pole 25, a magnetic gradient between the shielded
pole 25 and the main pole 15 of the vicinity of the ABS 70 can be
designed to be steep. As a result, jitter of a signal output
becomes small and an error rate during reading becomes small.
[0088] The shielded magnetic layer 26 is formed having a width of
approximately 0.5-5 .mu.m using, for example, the frame plating
method, the sputtering method, or the like. As a material for the
layer, an alloy configured of two or three elements, for example,
Ni, Fe, and Co, may be available. Or another alloy may also be
available, which is configured of the element(s) as primary
material and to which a predefined element is added.
[0089] Reference numbers 41 and 44 in FIG. 1 indicate insulation
layers.
[0090] For the embodiment of FIG. 1, the recording coils 23 are
designed to be wound around the main pole magnetic layer 16.
However, a general embodiment where the recording coils 23 are
wound around the intermediate connection part G as a center of a
winding axis in the Y-direction is also applicable.
(Description of Feature of Present Invention)
[0091] Hereafter, a feature of the present invention will be
described.
[0092] The feature of the present invention is that the microwave
band resonant magnetic field having the ferromagnetic resonant
frequency of the magnetic recording medium that is subjected to
recording or having the adjacent frequency thereof is radiated from
the microwave radiation waveguide 18 by interposing the microwave
radiation waveguide 18 made of a conductive nonmagnetic material (a
nonmagnetic metal) at the recording gap, which is the gap between
the main pole 15 and the shielded pole 25, and by applying the
microwave exciting current to the electric circuit formed by the
main pole magnetic layer 16, the microwave radiation waveguide 18,
and the shielded magnetic layer 26.
[0093] In order to configure the electric circuit for applying the
microwave exciting current with the main pole magnetic layer 16,
the microwave radiation waveguide 18 and the shielded magnetic
layer 26, the electrical insulation magnetic film 9 is disposed in
the intermediate connection part G that connects the main pole
magnetic layer and the shielded magnetic layer at the
depth-side.
[0094] In the present invention, the conductive nonmagnetic
material is mounted in a so-called write gap so as to function as
the microwave radiation waveguide 18, and the current flows in a
direction perpendicular to a film surface of the waveguide 18 (CPP
configuration). With a type where a coil is inserted to a known
write gap, current flows directly to the coil and the current is
not applied to the coil via a magnetic pole.
[0095] Since a frequency of the current in the present invention is
a desired high frequency, an external frequency modulator is
required to change the current therefor. When magnetic recording
data is recorded, the high frequency current is applied to the
magnetic pole to generate a data magnetic field from the magnetic
pole.
[0096] Hereafter, concrete materials, embodiments, etc. of the
microwave radiation waveguide 18 will be explained.
[0097] As described above, the microwave radiation waveguide 18 is
desirably configured of Ru, Ti or Ta. The most preferred one of
these is Ru. It is because a material of the magnetic pole and the
microwave radiation waveguide (CPW part) is easily distinguished
and sizes are easily measured when a shape is checked by SEM, etc.
With Ti or Ta, it becomes difficult to distinguish the magnetic
pole part and the CPW part and to measure the size.
[0098] The microwave radiation waveguide 18 is desired to adopt
preferable embodiments, which will be described below, in order to
electronically connect the main pole 15 with the shielded pole 25
and to radiate properly and effectively, from the microwave
radiation waveguide 18, the microwave band resonant magnetic field
having the ferromagnetic resonant frequency of the magnetic
recording medium that is subjected to recording or having the
adjacent frequency thereof.
First Embodiment
[0099] FIGS. 2 and 3A illustrate the first embodiment.
[0100] A microwave radiation waveguide 18 of the first embodiment
illustrated in FIGS. 2 and 3A has a width Wo in the X-direction of
the ABS, and the width is the same as a length of a side of an edge
part 15a of the main pole 15 on a trailing side.
[0101] The microwave radiation waveguide 18 is extended toward the
depth-side (the Y-direction) maintaining the width Wo in the
X-direction, and is configured in approximately a square shape as
illustrated in FIG. 3A when seen in a planar shape. A thickness
(the Z-direction) is a thickness so that all of the recording gap
is filled.
[0102] The microwave radiation waveguide 18 having the
approximately square shape when seen in the planar shape has the
advantage that manufacturing processes are relatively
simplified.
Second Embodiment
[0103] FIG. 3B illustrates the second embodiment.
[0104] Regarding a microwave radiation waveguide 18a of the second
embodiment illustrated in FIG. 3B, a view thereof seen from the ABS
is the same as the embodiment illustrated in FIG. 2. In other
words, a width Wo in the X-direction on the ABS is the same as the
length of the side of the edge part 15a on the trailing side of the
main pole 15. The width Wo becomes wider up to a width Wa
approaching the depth-side (the Y-direction) as illustrated in FIG.
3B. As a result, the waveguide 18a is configured in an
approximately trapezoidal shape where the width of the depth-side
is widened when seen in the planar shape. A thickness (the
Z-direction) is a thickness so that that all of the recording gap
is filled.
[0105] The microwave radiation waveguide 18a having the
approximately trapezoidal shape when seen in the planar shape has
an advantage where the intensity of the microwave magnetic field
from the ABS is raised.
[0106] A ratio of Wa/Wo is desirably approximately 1.5-3.0.
Third Embodiment
[0107] FIG. 3C illustrates the third embodiment.
[0108] Regarding a microwave radiation waveguide 18b of the third
embodiment illustrated in FIG. 3C, a view thereof seen from the ABS
is the same as the embodiment illustrated in FIG. 2. In other
words, the width Wo in the X-direction on the ABS is the same as
the length of the side of the edge part 15a on the trailing side of
the main pole 15. The width Wo is widened approaching the
depth-side (the Y-direction). The waveguide 18b branches into two
waveguide parts (a width We) elongating toward the depth-side and
outwards (namely, in the X-direction), and it is configured
approximately in a V-shape when seen in the planar shape.
[0109] A thickness (the Z-direction) is a thickness so that all of
the recording gap is filled. An inside of the approximate V-shape
is filled with a nonmagnetic material 44a.
[0110] The microwave radiation waveguide 18b as seen in the planar
shape configured approximately in a square shape has an advantage
where the intensity of the microwave magnetic field from the ABS is
further raised.
[0111] A ratio of Wb/Wo is approximately 2.0-5.0. A ratio of Wc/Wo
is approximately 0.5-1.5.
Fourth Embodiment
[0112] FIGS. 4 and 5A illustrate the fourth embodiment.
[0113] A microwave radiation waveguide 18c of the fourth embodiment
illustrated in FIGS. 4 and 5A has two cuboid waveguides 18'c and
18'c, which are arranged to cover both end edges 15b and 15b of the
edge part 15a on the trailing side of the main pole 15.
[0114] A maximum arrangement width We of the waveguide 18c is
approximately 1.0-1.5 of a ratio of We/Lo related to a length Lo of
the side of the edge part 15a on the trailing side of the main pole
15. Width Wd between each of the waveguides 18'c and 18'c is set to
be Wd/Lo=approximately 0.2-0.5 with respect to Lo. In a gap between
the two waveguides 18'c and 18'c, the nonmagnetic material 44a is
filled.
[0115] Such a microwave radiation waveguide 18c effectively makes
up for a deterioration of a main pole magnetic field especially on
the track edge part. As a result, a magnetic field that is
uniformly stable in the track width direction is obtained, a
deterioration of a recording quality on the track edge part is
prevented, and the stable recording pattern is recorded on the
medium.
Fifth Embodiment
[0116] FIG. 5B illustrates the fifth embodiment.
[0117] Regarding a microwave radiation waveguide 18d of the fifth
embodiment illustrated in FIG. 5B, a view thereof seen from the ABS
is the same as the fourth embodiment illustrated in FIG. 4.
[0118] The difference of the microwave radiation waveguide 18d
illustrated in FIG. 5B from the fourth embodiment illustrated in
FIG. 5A is that waveguides 18'd and 18'd are linked at the rear
side part of the depth-side (the Y-direction) so as to be
approximately in a U-shape. The waveguides 18'd and 18'd are two
cuboids arranged to correspond to (or to cover) both end edges 15b
and 15b of the edge part 15a on the trailing side of the main pole
15 at the ABS.
[0119] The thickness (in the Z-direction) is sufficient to fill the
recording gap. The nonmagnetic material 44a is present inside of
the U-shape.
[0120] The microwave radiation waveguide 18d especially effectively
makes up for a deterioration of the main pole magnetic field at the
track edge part, the same as the above-described fourth embodiment.
As a result, a uniformly stable magnetic field in the track width
direction is obtained, a deterioration of recording quality at the
track edge part is prevented, and a stable recording pattern is
recorded on the medium.
Sixth Embodiment
[0121] FIGS. 6 and 7 illustrate the sixth embodiment.
[0122] A microwave radiation waveguide 18 of the sixth embodiment
illustrated in FIGS. 6 and 7 is basically configured the same as
the embodiments illustrated in FIGS. 2 and 3A, the embodiment
illustrated in FIG. 3B, and/or the embodiment illustrated in FIG.
3C.
[0123] In the sixth embodiment illustrated in FIGS. 6 and 7, a
structure of a shielded magnetic layer is especially different. A
shielded magnetic layer 26' of the sixth embodiment illustrated in
FIGS. 6 and 7 is configured for a magnetic head of a so-called
wrap-around shield type. When seen from the ABS that is a surface
facing the magnetic recording medium, the shielded magnetic layer
26' is configured as a comprehensive shielded pole 25' that is
formed so as to surround an approximately whole part of the main
pole 15 via a nonmagnetic part 44b that is partially formed in the
periphery of the main pole 15 (wrap-around shield).
[0124] In FIG. 7, as seen from the ABS; the main pole 15 and the
shielded pole 25' are electrically connected via the microwave
radiation waveguide 18. The shielded pole 25' and the other part of
the periphery part of the main pole 15 is insulated by the
nonmagnetic part 44b.
[0125] Such a microwave radiation waveguide 18 has an advantage in
an assisted magnetic field having a better quality for suppressing
a leaking of a magnetic field to an adjacent track.
[0126] When seen from the ABS that is a surface facing the magnetic
recording medium, the shielded magnetic layer 26 of the embodiment
illustrated in FIGS. 2 and 3A has a magnetic head structure
providing only the shielded pole 25 positioned facing the main pole
15 in the Z-direction. This is referred to as a non-wrap-around
shield type.
Seventh Embodiment
[0127] FIG. 8A illustrates the seventh embodiment.
[0128] The seventh embodiment illustrated in FIG. 8A is a magnetic
head of the wrap-around shield type the same as the sixth
embodiment.
[0129] A microwave radiation waveguide 18e of the seventh
embodiment is configured having two L-shaped waveguides 18'e and
18'e positioned so as to surround corners of both of the end edges
15b and 15b of an edge part 15a on the trailing side of the main
pole 15.
[0130] The main pole 15 and the shielded pole 25' are electrically
connected via the microwave radiation waveguide 18e, and the other
part of the periphery part of the main pole 15 is insulated by a
nonmagnetic part 44c.
[0131] A part substantially effective as the microwave radiation
waveguide 18e in the seventh embodiment is areas illustrated as WG
in the figures.
Eighth Embodiment
[0132] FIG. 8B illustrates the eighth embodiment.
[0133] The eighth embodiment illustrated in FIG. 8B is a magnetic
head of the wrap-around shield type the same as the above-described
sixth and seventh embodiments.
[0134] Regarding a microwave radiation waveguide 18f of the eighth
embodiment, a part of the edge part 15a on the trailing side of the
main pole 15 at the ABS illustrated in FIG. 8B is covered with a
nonmagnetic part 44c, and the other part of the periphery of the
main pole 15 is covered with the microwave radiation waveguide 18f
in a V-shape.
[0135] Such an embodiment is also deemed as an embodiment where a
microwave radiation waveguide made of a conductive nonmagnetic
material (nonmagnetic metal) is disposed in the recording gap that
is a gap between the main pole and the shielded pole of the present
invention. This is because a part substantially effective as the
microwave radiation waveguide 18f in the eighth embodiment becomes
an area illustrated as WG in the figure.
(Description of Head Gimbal Assembly and Hard Disk Device)
[0136] Next, an example of a head gimbal assembly and a hard disk
device in which the above-described microwave assisted magnetic
head is installed is described.
[0137] First, with reference to FIG. 9, a slider 210 included in
the head gimbal assembly is described. In a hard disk device, the
slider 210 is positioned to face a hard disk, which is a rotated
disk-shaped recording medium. The slider 210 primarily includes a
base 211 configured from a substrate and an overcoat.
[0138] The base 211 has a hexahedronal shape. One of the six sides
of the base 211 faces the hard disk. The ABS 70 is formed on this
side.
[0139] As the hard disk rotates in the Z-direction in FIG. 9, a
lift force is generated for the slider 210 in the downward
direction in the Y-direction shown in FIG. 9 due to an air flow
passing between the hard disk and the slider 210. The slider 210
flies on the surface of the hard disk due to the lift force. The
X-direction in FIG. 9 is a track crossing direction of the hard
disk.
[0140] A thin film magnetic head according to the present
embodiment is formed near an air outflow-side edge (left lower edge
in FIG. 9) of the slider 210.
[0141] Next, a head gimbal assembly 220 according to the present
embodiment is described with reference to FIG. 10. The head gimbal
assembly 220 includes the slider 210 and a suspension 221 that
elastically supports the slider 210. The suspension 221 includes a
plain spring load beam 222 formed from, for example, stainless
steel, a flexure 223 that is provided at one edge of the load beam
222 and connected to the slider 210 and that provides a proper
degree of freedom to the slider 210, and a base plate 224 provided
at the other edge of the load beam 222.
[0142] The base plate 224 is mounted to an arm 252 of an actuator
for moving the slider 210 in the track crossing direction x of the
hard disk 262. The actuator has the arm 252 and a voice coil motor
that drives the arm 252. A gimbal part for maintaining the position
of the slider 210 constant is provided at a part of the flexure
223, to which the slider 210 is mounted.
[0143] The head gimbal assembly 220 is mounted at the arm 252 of
the actuator. An assembly, in which the head gimbal assembly 220 is
mounted to a single arm 252, is referred to as a head arm assembly.
An assembly, in which the head gimbal assembly 220 is mounted to
each arm of a carriage having multiple arms, is referred to as a
head stack assembly.
[0144] FIG. 10 illustrates an example of a head arm assembly. In
the head arm assembly, the head gimbal assembly 220 is mounted to
one end of the aim 252. To the other end of the arm 252, a coil
253, which is a part of the voice coil motor, is mounted. In the
middle part of the arm 252, a bearing part 233 that is mounted to a
shaft 234 so that the arm 252 is rotatably supported.
[0145] Next, an example of a head stack assembly and a hard disk
device according to the embodiment are described with reference to
FIGS. 11 and 12.
[0146] FIG. 11 is an explanatory view of a main part of the hard
disk device, and FIG. 12 is a plan view of the hard disk
device.
[0147] A head stack assembly 250 includes a carriage 251 including
a plurality of arms 252. A plurality of head gimbal assemblies 220
are mounted respectively to the plurality of arms 252 such that the
head gimbal assemblies 220 in the perpendicular direction have gaps
between each other. The coil 253 that is part of the voice coil
motor is mounted on the end of the carriage 251 opposite from the
arm 252. The head stack assembly 250 is installed in the hard disk
device.
[0148] The hard disk device has multiple hard disks 262 mounted to
a spindle motor 261. At each hard disk 262, two sliders 210 are
positioned facing each other and sandwiching the hard disk 262. The
voice coil motor has permanent magnets 263 positioned facing each
other and sandwiching the coil 253 of the head stack assembly
250.
[0149] The head stack assembly 250 and the actuator, excluding the
slider 210, correspond to a positioning device in the present
invention. The head stack assembly 250 and the actuator support and
position the slider 210 with respect to the hard disk 262.
[0150] In the hard disk device according to the present embodiment,
the actuator positions the slider 210 with respect to the hard disk
262 by moving the slider 210 in the track crossing direction of the
hard disk 262. The thin film magnetic head included in the slider
210 records information on the hard disk 262 by a recording head
and reproduces the information recorded on the hard disk 262 by a
reproducing head.
[0151] The head gimbal assembly and the hard disk device according
to this embodiment are as effective as the thin film magnetic head
according to the above-described embodiment.
[0152] Moreover, in the embodiment, a thin film magnetic head with
a structure, in which a reproducing head part is formed on the base
substrate side and the perpendicular recording head part is
laminated thereon, was discussed. However, the order of the
lamination may be reversed. Further, when the thin film magnetic
head is used exclusively for reproducing information, only a
reproducing head part may be provided.
Detailed Examples
[0153] Hereafter, detailed examples regarding the microwave
assisted magnetic head of the present invention are described so
that a further detailed explanation of the present invention will
be given.
Example 1
Manufacturing of Samples of Example 1
[0154] A microwave assisted magnetic head (the present invention)
of the wrap-around shield type, which provides a microwave for
microwave radiation 18 as illustrated in FIGS. 6 and 7, was
designed. An exemplary simulation of a wedge shaped magnetic field
distribution, which was generated from the waveguide and was
protruded in the -Y direction, was executed, and a characteristic
value was obtained.
[0155] Settings of a main part configuring the head were as
follows.
<The Microwave Radiation Waveguide 18>
Material: Ru
Width (X-direction): 50 nm
Depth (Y-direction): 30 nm
Thickness (Z-direction): 30 nm
[0156] Inclined angle .theta.: 25.degree.
<Main Pole 15>
Material: FeCo
<Shielded Pole 25' (Wrap-Around Shield Type)>
Material: NiFe
[0157] <Nonmagnetic Part 44b>
Material: Alumina (Al.sub.2O.sub.3)
[0158] A modeling state of a magnetic field distribution was
illustrated in FIG. 13. The magnetic field forming the distribution
was emitted from the waveguide 18 to which the microwave (frequency
20 GHz, output 10 mW) was applied, the microwave radiation
waveguide 18 of the sample of example 1 providing the
above-described setting. Also, the magnetic field distribution was
illustrated as a wedge shape protruded in the -Y direction
(directed to the facing magnetic recording medium).
[0159] According to the result illustrated in FIG. 13, a part
closer to a tip of the wedge shape protruded in the -Y direction
has a larger magnetic field intensity. Even when a small amount of
power, 10 mW, was applied, the magnetic field intensity of
approximately 800 [Oe] emerged at the tip-most part. When the power
was increased, the magnetic field was increased in proportion to
the power. Therefore, a required assisted magnetic field was
arbitrarily adjusted together with power.
[0160] Furthermore, a magnetic field distribution of the thickness
direction (the Z-direction: the same as the trail direction) and
the width direction (the X-direction: the same as the off-track
direction) of the waveguide 18 were obtained and illustrated in
FIGS. 14 and 15.
[0161] As illustrated in FIG. 14, a steep magnetic field
distribution was obtained in the Z-direction: the trail direction.
As illustrated in FIG. 15, a magnetic field distribution having a
track width of 100 nm in the X-direction: off track direction was
obtained.
[0162] Then, it was simulated that the high-frequency assisted
magnetic field generated from the microwave radiation waveguide 18
overlapped the normal head recording magnetic field and that the
magnetic recording was executed.
Manufacturing of Samples of Example 2
[0163] A microwave assisted magnetic head of the shield type (the
present invention) providing a microwave radiation waveguide 18 as
illustrated in FIGS. 2 and 3 was designed. An exemplary simulation
of a wedge shaped magnetic field distribution that was generated
from the waveguide and was protruded in the -Y direction was
executed, and a characteristic value was obtained.
[0164] Settings of a main part were almost the same as the sample
of the above-described example 1.
[0165] Furthermore, a magnetic field distribution of the thickness
direction (the Z-direction: the same as the trail direction) and
the width direction (the X-direction: the same as the oil-track
direction) of the waveguide 18 was obtained by the same procedure
as the sample of example 1. Results of the sample of example 2 were
the same as the results illustrated in FIGS. 14 and 15 for the
sample of example 1.
Manufacturing of Samples of Example 3
[0166] In this sample, the microwave radiation waveguide is
configured to be a structure as illustrated in FIG. 3C. Except for
the waveguide, samples of the microwave assisted magnetic head (the
present invention) for example 3 were configured the same as the
sample of the above-described example 2, an exemplary simulation of
a wedge shaped magnetic field distribution that was generated from
the waveguide and was protruded in the -Y direction was executed,
and a characteristic value was obtained.
[0167] Then, with the same procedure as the sample of example 1, a
magnetic field distribution of the thickness direction (the
Z-direction: the same as the trail direction) and the width
direction (the X-direction: the same as the off-track direction) of
a part of the microwave radiation waveguide 18 was obtained. As a
result, there was no change for the magnetic field distribution of
the thickness direction (the Z-direction: the same as the trail
direction) of the part of waveguide 18. On the other hand, as
illustrated in FIG. 16, the magnetic field distribution of the
width direction (the X-direction: the same as the off-track
direction) was further flattened in a vicinity of a maximum value
of the intensity distribution.
[0168] Therefore, it was confirmed that a magnetic field profile
was controlled depending on the shapes in which the microwave
radiation waveguide was set.
[0169] According to the above results, the advantages of the
present invention are obvious.
[0170] Namely, a microwave assisted magnetic head of the present
invention is formed to include a main pole magnetic layer including
a main pole; a shielded magnetic layer including a shielded pole; a
recording coil that is formed to generate a writing magnetic field
from a tip of the main pole; and a microwave radiation waveguide
made of a conductive nonmagnetic material that is disposed in a
recording gap, the recording gap being a gap between the main pole
and the shielded pole. The main pole magnetic layer and the
shielded magnetic layer have an intermediate connection part that
connects the layers at a depth-side, and an electrical insulation
magnetic film is disposed in the intermediate connection part, and
the main pole and the shielded pole are electrically connected with
the microwave radiation waveguide that is disposed in the recording
gap, which is the gap between the main pole and the shielded pole.
Therefore, the present invention provides the microwave assisted
magnetic head that has a novel configuration, having a simple
configuration, a relatively easy manufacturing process, high
efficiency, and that overlaps the AC magnetic field in an in-plane
direction of the microwave band, which is the same as, or close to,
the ferromagnetic resonant frequency of the medium recording
layer.
* * * * *