U.S. patent application number 10/136694 was filed with the patent office on 2002-08-29 for information reproduction head apparatus and information recording/reproduction system.
This patent application is currently assigned to NEC CORPORATION. Invention is credited to Hayashi, Kazuhiko.
Application Number | 20020118494 10/136694 |
Document ID | / |
Family ID | 26538050 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020118494 |
Kind Code |
A1 |
Hayashi, Kazuhiko |
August 29, 2002 |
Information reproduction head apparatus and information
recording/reproduction system
Abstract
The present invention provides a yoke-type information
reproduction head apparatus 100 having a magnetic sensor block 3
provided on the substrate 1 via a non-magnetic insulation layer 2.
The magnetic sensor 3 includes a ferromagnetic tunnel junction
element 5 which is sandwiched between an upper electrode block 6
and a lower electrode block 7 and which is connected to a magnetic
domain control bias layer 8. This enables to obtain preferable S/N
and bit error rate with reduced waveform noise. This invention
provides a yoke-type information reproduction head having both of
the characteristics of the front yoke 4-1 as a magnetic path and a
lower electrode 7 as an electric path.
Inventors: |
Hayashi, Kazuhiko; (Tokyo,
JP) |
Correspondence
Address: |
FOLEY AND LARDNER
SUITE 500
3000 K STREET NW
WASHINGTON
DC
20007
US
|
Assignee: |
NEC CORPORATION
|
Family ID: |
26538050 |
Appl. No.: |
10/136694 |
Filed: |
April 29, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10136694 |
Apr 29, 2002 |
|
|
|
09384434 |
Aug 27, 1999 |
|
|
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Current U.S.
Class: |
360/324.2 ;
G9B/5.122; G9B/5.124 |
Current CPC
Class: |
B82Y 10/00 20130101;
G11B 5/3113 20130101; B82Y 25/00 20130101; G11B 5/3925 20130101;
G11B 5/3909 20130101; G11B 5/3932 20130101 |
Class at
Publication: |
360/324.2 |
International
Class: |
G11B 005/39 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 1998 |
JP |
10-247095 |
Sep 1, 1998 |
JP |
10-247093 |
Claims
What is claimed is:
1. A yoke type information reproduction head apparatus comprising a
magnetic sensor block placed on a non-magnetic insulation layer
provided on a substrate, the magnetic sensor being connected to a
magnetic pole and including a ferromagnetic tunnel junction element
sandwiched by an upper electrode block and a lower electrode block,
wherein the tunnel junction element is in junction with a magnetic
domain control bias layer.
2. A yoke type information reproduction head apparatus as claimed
in claim 1, wherein the bias layer is in junction a with free
magnetic layer constituting a tunnel junction element.
3. A yoke type information reproduction head apparatus as claimed
claim 1, wherein the bias layer is at least partially overlaid on
the free magnetic layer.
4. A yoke type information reproduction head apparatus as claimed
claim 2, wherein the bias layer is at least partially overlaid on
the free magnetic layer.
5. A yoke type information reproduction head apparatus as claimed
claim 1, wherein the bias layer has a rectangular shape and one
side of the rectangular shape is in junction with the end portion
of the free magnetic layer or a part of the rectangular shape is
overlaid on the end portion of the free magnetic layer.
6. A yoke type information reproduction head apparatus as claimed
claim 2, wherein the bias layer has a rectangular shape and one
side of the rectangular shape is in junction with the end portion
of the free magnetic layer or a part of the rectangular shape is
overlaid on the end portion of the free magnetic layer.
7. A yoke type information reproduction head apparatus as claimed
claim 1, wherein the bias layer is arranged in a direction
vertically intersecting the magnetic pole.
8. A yoke type information reproduction head apparatus as claimed
claim 2, wherein the bias layer is arranged in a direction
vertically intersecting the magnetic pole.
9. A yoke type information reproduction head apparatus as claimed
in claim 1, wherein the non-magnetic insulation layer is buried in
the substrate.
10. A yoke type information reproduction head apparatus as claimed
in claim 1, wherein the magnetic pole is connected to at least one
of the upper electrode block and the lower electrode block
connected to the tunnel junction element.
11. A yoke type information reproduction head apparatus as claimed
in claim 10, wherein the magnetic pole is constituted by a first
magnetic pole and a second magnetic pole located oppositely with
respect to the tunnel junction element and the first magnetic pole
is arranged at the side where a medium is present.
12. A yoke type information reproduction head apparatus as claimed
in claim 1, wherein the bias layer is made from a ferromagnetic
material or hard magnetic material.
13. An information recording reproduction system comprising: a
magnetic storage medium having a plurality of tracks for recording
information; a magnetic recording apparatus for storing the
information onto the magnetic storage medium; the information
reproduction head apparatus described in claim 1; and an actuator
connected to the magnetic recording apparatus and to the
information reproduction head apparatus, for moving the magnetic
recording apparatus and the information reproduction head to a
selected one of tracks of the magnetic recording medium.
14. A yoke type information reproduction head apparatus comprising
a magnetic sensor block placed on a non-magnetic insulation layer
provided on a substrate, the magnetic sensor being connected to a
magnetic pole and including a ferromagnetic tunnel junction element
sandwiched by an upper electrode block and a lower electrode block,
wherein the apparatus includes a front yoke block and a rear yoke
block arranged at the opposing positions with respect to the tunnel
junction element, the front yoke being located at the side of the
tunnel junction element where a medium is present
15. A yoke type information reproduction head apparatus as claimed
in claim 14, wherein at least a portion of the front yoke block is
overlaid over at least a portion of the lower magnetic pole via the
tunnel junction element.
16. A yoke type information reproduction head apparatus as claimed
in claim 14, wherein the front yoke block has an end portion in
abutment with an end portion of the tunnel junction element.
17. A yoke type information reproduction head apparatus as claimed
in claim 15, wherein the front yoke block has an end portion in
abutment with an end portion of the tunnel junction element.
18. A yoke type information reproduction head apparatus as claimed
in claim 16, wherein the junction surface between the front yoke
block and the tunnel junction element has a tapered shape.
19. A yoke type information reproduction head apparatus as claimed
in claim 17, wherein the junction surface between the front yoke
block and the tunnel junction element has a tapered shape.
20. A yoke type information reproduction head apparatus as claimed
in claim 14, wherein the end portion of the front yoke block is
engaged with the end portion of the tunnel junction element.
21. A yoke type information reproduction head apparatus as claimed
in claim 14, wherein the bias layer is formed in a direction
orthogonally intersecting the yoke block.
22. An information recording reproduction system comprising: a
magnetic storage medium having a plurality of tracks for recording
information; a magnetic recording apparatus for storing the
information onto the magnetic storage medium; the information
reproduction head apparatus described in claim 14; and an actuator
connected to the magnetic recording apparatus and to the
information reproduction head apparatus, for moving the magnetic
recording apparatus and the information reproduction head to a
selected one of tracks of the magnetic recording medium.
Description
[0001] This application is a division of application Ser. No.
09/384,434, filed Aug. 27, 1999, now pending, and based on Japanese
Patent Application No. JP 10-247095, filed Sep. 1, 1998, by
Kazuhiko HAYASHI. This application claims only subject matter
disclosed in the parent application and therefore presents no new
matter.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to an information reproduction
head apparatus for reading an information signal recorded on a
magnetic medium and an information recording/reproducing system
using the information reproduction head and in particular, to an
information reproduction head apparatus and an information
recording/reproducing system realizing a small-hysteresis R-H loop
and including yoke type magnetoresistance effect sensor using a
tunneling magnetoresisstivity (TMR).
[0004] The present invention also relates to an information
reproduction head apparatus for reading an information signal
recorded on a magnetic medium, and to an information
recording/reproduction system using the information reproduction
head and in particular, to eliminate a positional interference
between the front yoke portion and the bottom electrode, so as to
enable to obtain the dynamic path of the front yoke portion and the
electro-conductive characteristic of the bottom electrode.
[0005] 2. Description of the Related Art
[0006] As a conventional technique, a magnetic read converter
called magneto-resistance effect (MR) sensor or head has been
disclosed. Here, a data is read from a magnetic surface with a high
linear density. The MR sensor detects a magnetic signal through a
resistance change as a function of a magnetic flux intensity and
direction detected by a read element.
[0007] This conventional MR sensor operates according to the
anisotropic magnetic resistance (AMR) effect in which one
resistance component of the read element changes in proportion to
cosine of the angle defined by the magnetization direction and the
electric current flowing through the element. The AMR effect is
detailed in D. A. Thompson et al "Memory, Storage, and Related
Applications", IEEE Trans. on Mag. MAG-11, p.1039, (1975).
[0008] In the magnetic head using the AMR effect is usually
subjected to longitudinal bias so as to suppress the Barkhausen
noise. This longitudinal bias is applied using FeMn, NiMn, nickel
oxide and other antiferromagnetic material.
[0009] Furthermore, recently it is described that the more
remarkable resistance change of the layered magnetic sensor is
caused by an electron spin dependency between magnetic layers
sandwiching a non-magnetic layer and accompanying spin-dependent
scattering on the boundary surface. This magneto-resistance effect
is called "gigantic magneto-resistance effect", "spin valve
effect", or the like. Such magneto-resistance sensor is made from
an appropriate material and has a higher sensitivity and greater
resistance change than the sensor using the AMR effect.
[0010] In this type of MR sensor, a pair of ferromagnetic layers
isolated by a non-magnetic layer changes in proportion to the
cosine of the magnetic direction angle of the magnetization
directions of the two ferromagnetic layers.
[0011] On the other hand, Japanese Patent Publication A2-61572
discloses a layered magnetic structure which brings a high MR
change caused by the non-parallel arrangement of the magnetization
of the magnetic layers. The layered structure may be made from a
ferromagnetic transient metal or alloy. Moreover, it is disclosed
that one of the at least two ferromagnetic layers isolated from
each other by an intermediate layer is fixed by a FeMn.
[0012] Furthermore, Japanese Patent Publication (unexamined)
A4-358310 discloses an MR sensor having two thin film ferromagnetic
layers isolated from each other by a non-magnetic metal thin layer.
If a magnetic field applied is 0, the magnetization direction of
the two ferromagnetic thin film layers intersect vertically and the
resistance of the two non-connected ferromagnetic layers changes in
proportion to the cosine of the angle defined by the magnetization
direction of the two layers, which is independent of the current
flowing in the sensor.
[0013] Moreover, Japanese Patent Publication (unexamined) A4-103014
discloses a ferromagnetic tunneling magnetoresistivity of a multi
ferromagnetic layers inserted by an intermediate layer, in which at
least one of the ferromagnetic layers is subjected to a bias
magnetic field from an antiferromagnetic body.
[0014] Furthermore, Japan Mag. Society, proceeding, 1996, page 135
describes a tunneling magnetoresistivity constituted by a free
magnetic layer made from Co and a fixed magnetic layer made from
NiFe.
[0015] Moreover, Japanese Patent Publication (unexamined)
A10-162327 discloses a tunneling magnetoresistivity (TMR) apparatus
and magnetoresistance (MR) read head configuration. The TMR
apparatus is applied to a so-called shield type magnetoresistance
read head, and no description is given on the yoke type information
reproduction head having a TMR element with a longitudinal bias
layer under a particular condition.
[0016] When producing a yoke-type MR sensor using a ferromagnetic
TMR junction element, there is a problem that the loop
corresponding to the inversion of the free layer of the R-H loop
has a high hysterisis and accordingly, when a magnetic information
recorded on a magnetic recording medium is reproduced by the
sensor, the reproduction waveform has much Barkhausen noise.
SUMMARY OF THE INVENTION
[0017] It is therefore an object of the present invention to
provide a yoke-type magnetoresistance effect (MR) sensor realizing
a small-hysteresis R-H loop and using a tunnel junction element
capable of obtaining a preferable reproduction waveform.
[0018] Moreover, in a conventional magnetoresistance effect element
using a ferromagnetic tunnel junction, among the elements
constituting the ferromagnetic tunnel junction, one of the free
magnetic layer and the fixed magnetic layer is used an upper
electrode and the other is used as a lower electrode.
[0019] However, in such an element, the element resistance is
affected not only by the tunnel resistance but also electrode
resistance of the lower and upper ferromagnetic layers.
Accordingly, the resistance change becomes smaller and the current
does not flow uniformly in the tunnel junction element.
[0020] For this, the free magnetic layer and the fixed magnetic
layer cannot be used directly as electrodes but a small-resistance
layer should be provided as an upper electrode and a lower
electrode.
[0021] On the other hand, in the yoke type head, the magnetic flux
taken from the medium by the front yoke should be effectively
introduced to the free magnetic layer so as to obtain a greater
reproduction output.
[0022] For this, it is necessary that the yoke end portion and the
free magnetic layer end portion be located at close positions. When
using a ferromagnetic tunnel junction element constituted by a free
magnetic layer, a non-magnetic layer, a fixed magnetic layer, and
fixation layer, the yoke should be provided immediately under the
free magnetic layer and partially overlain.
[0023] However, the lower electrode also should be located under
the ferromagnetic tunnel junction element. Thus, even if designed
correctly, positional competition brings about a problem of an
element production accuracy. The yoke is overlain with the
electrode, which causes various problems of electric
characteristics, magnetic characteristics, and head production.
[0024] Accordingly, another object of the present invention is to
provide a yoke type information reproduction apparatus in which
there is no interference between the front yoke and the lower
electrode so as to obtain simultaneously a magnetic path of the
front yoke and an electric path of the lower electrode, and to
provide an information recording/reproduction system using the yoke
type information reproduction apparatus as a second embodiment of
the present invention.
[0025] The first embodiment employs various basic techniques to
achieve the aforementioned object. That is, the information
reproduction head according to the first embodiment of the present
invention is a yoke type information reproduction head apparatus
including a substrate on which a magnetic sensor block is provided
via a non-magnetic insulation layer. The magnetic sensor block is
connected to a magnetic pole. The magnetic sensor block includes a
ferromagnetic tunnel junction element sandwiched by the upper
electrode and the lower electrode. The tunnel junction element is
connected a bias layer for magnetic domain control.
[0026] The second embodiment, in order to achieve the
aforementioned object, employs a technical configuration as
follows. A magnetic sensor block is mounted on a substrate via a
non-magnetic insulation layer and the magnetic sensor block is a
connected to a yoke block, constituting a yoke type information
reproduction head apparatus, including a front yoke portion
provided in a direction where a medium exists with respect to the
tunnel junction element and a rear yoke portion in the opposite
direction with respect to the tunnel junction element, wherein at
least a part of the front yoke portion and at least a part of the
lower magnetic pole are located on different surfaces of the tunnel
junction element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] FIG. 1A shows a reproduction head apparatus according to a
first embodiment of the present invention; and FIG. 1B is an
enlarged view of a magnetic sensor used in FIG. 1A.
[0028] FIG. 2 shows a configuration example of the reproduction
head apparatus according to the first embodiment of the present
invention.
[0029] FIG. 3 is a plan view of showing an example of junction
state between the tunnel junction element and a bias layer in the
reproduction head of the first embodiment.
[0030] FIG. 4 is a plan view of another example of junction state
between the tunnel junction element and the bias layer in the
reproduction head of the first embodiment.
[0031] FIG. 5 is a plan view of still another example of junction
state between the tunnel junction element and the bias layer in the
reproduction head of the first embodiment.
[0032] FIG. 6 is a perspective view of a configuration example of
the recording/reproduction head used in the information
recording/reproduction system according to the present
invention.
[0033] FIG. 7 is an application example of the
recording/reproduction head used in the information
recording/reproduction system according to the present
invention.
[0034] FIG. 8 is an enlarged plan view of a fist example of the
information reproduction head apparatus according to the present
invention, with dimensions indicated.
[0035] FIG. 9 is an enlarged plan view of a second example of the
information reproduction head apparatus according to the present
invention, with dimensions indicated.
[0036] FIG. 10 shows a reproduction output, S/N, mark length
(frequency) decreasing the reproduction output by half, a bit error
rate, and reproduction waveform of a head prepared without using
the magnetic domain control bias layer.
[0037] FIG. 11 shows a reproduction output, S/N, mark length
(frequency) decreasing the reproduction output by half, a bit error
rate, and reproduction waveform of a head (arranged as in FIG. 3)
prepared by changing the material of the magnetic domain control
bias layer.
[0038] FIG. 11 shows a reproduction output, S/N, mark length
(frequency) decreasing the reproduction output by half, a bit error
rate, and reproduction waveform of a head (arranged as in FIG. 4)
prepared by changing the material of the magnetic domain control
bias layer.
[0039] FIG. 12 shows a reproduction output, S/N, mark length
(frequency) decreasing the reproduction output by half, a bit error
rate, and reproduction waveform of a head (arranged as in FIG. 5)
prepared by changing the material of the magnetic domain control
bias layer.
[0040] FIG. 14A is a cross sectional view of a specific example of
the information reproduction head apparatus according to a second
embodiment of the present invention; and FIG. 14B is an enlarged
view of a magnetic sensor block.
[0041] FIG. 15 is a cross sectional view of another specific
example of the information reproduction head apparatus according to
the second embodiment of the present invention.
[0042] FIG. 16 is a cross sectional view of yet another specific
example of the information reproduction head apparatus according to
the second embodiment of the present invention.
[0043] FIG. 17 is a cross sectional view of yet still another
specific example of the information reproduction head apparatus
according to the second embodiment of the present invention.
[0044] FIG. 18 is a plan view of a configuration example of the
information reproduction head apparatus according to the second
embodiment of the present invention.
[0045] FIG. 19 is a plan view of a configuration example of the
information reproduction head apparatus according to the second
embodiment of the present invention with dimensions indicated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0046] The information reproduction head apparatus according to the
first embodiment is a yoke-type magnetoresistance effect head
having a yoke for the magnetoresistance effect element, wherein a
tunnel junction element is used for the magnetic sensor block. For
example, a rectangular ferromagnetic material or hard magnetic
material for the magnetic domain stabilizing element of a free
magnetic layer of the tunnel junction element. The shorter side of
the magnetic domain stabilizing element is in contact with the
tunnel junction element or partially overlain.
[0047] In the first embodiment of the present invention,
magnetization of the magnetic domain stabilizing element is
arranged in one direction. A portion of the free magnetic layer of
the magnetoresistance effect element which is in contact with the
magnetic domain stabilizing element or is overlain can have a
uniform magnetization direction. This suppresses generation of a
magnetic domain in the free magnetic layer.
[0048] With the aforementioned configuration, the magnetic reverse
mode is changed from a magnetic wall movement mode to a magnetic
rotation mode, so as to realize an R-H loop of small hysteresis,
enabling to obtain a preferable waveform.
[0049] The information reproduction head apparatus and the
information recording/reproduction system according to the second
embodiment employ the aforementioned basic techniques. In the
yoke-type magnetoresistance effect head, the magnetic sensor block
using a tunnel junction element having, for example, a fixing
layer, a fixed magnetic layer, a non-magnetic layer, and a free
layer and including an upper electrode block located on the top of
the tunnel junction and a lower electrode block located below the
tunnel junction in such a manner that at least a portion of the
lower electrode and at least a portion of the front yoke are
located in the opposing position with respect to the tunnel
junction element.
[0050] Thus, the electric current can flow uniformly in the tunnel
junction element. Since the front yoke and the lower electrode are
located not to interfere with each other, it is possible to obtain
a characteristic as a magnetic path of the front yoke and the
electric path of the lower electrode.
[0051] [Embodiment 1]
[0052] Description will now be directed to a configuration example
of the information reproduction head apparatus and the information
recording/reproduction system according to the first embodiment of
the present invention with reference to the attached drawings.
[0053] That is FIG. 1 a cross sectional view and FIG. 2 a plan view
of configuration example of the information reproduction head
apparatus according to the present embodiment. This is a yoke type
information reproduction head apparatus 100, wherein a magnetic
sensor block 3 is provided on a substrate 1 via a non-magnetic
insulation layer 2, and the sensor block 3 is connected to a
magnetic pole 4. The magnetic sensor block 3. In this yoke type
information reproduction head apparatus 100, the magnetic sensor
block 3 includes a ferromagnetic tunnel junction element 5
sandwiched by an upper electrode 6 and a lower electrode 7. This
tunnel junction element 5 is in junction with the magnetic domain
control bias layer 8.
[0054] In the information reproduction head apparatus 100 according
to the present invention, the tunnel junction element 5, as shown
in FIG. 1B for example, it is preferable that the tunnel junction
element include a sensor substrate 10, a fixed magnetic layer 11, a
non-magnetic barrier layer 12, and a free magnetic layer 13 which
are successively layered in this order. Moreover, in this
invention, it is preferable that the bias layer 8 be in junction
with the free magnetic layer 13.
[0055] In this invention, it is preferable that at least a portion
of the bias layer 8 be overlain with a portion of the free magnetic
layer. More specifically, the bias layer 8 in plan view has a
rectangular shape, and is arranged so that one side of the
rectangular layer 8 is in junction with the end of the free
magnetic layer 13.
[0056] That is, FIG. 3 shows a free magnetic layer 13 in the tunnel
junction element 5 and the magnetic domain control bias layer 8 are
in junction with their end portions. FIG. 4 shows the end portions
of the free magnetic layer 13 and the magnetic control bias layer 8
are overlain.
[0057] Furthermore, FIG. 5 shows that the entire free magnetic
layer 13 is on the magnetic domain control bias layer 8.
[0058] On the other hand, according to the present invention, it is
preferable that the bias layer 8 be arranged in a direction
vertical to the magnetic pole 4. Furthermore, it is preferable that
the bias layer 8 be made from a antiferromagnetic material or hard
magnetic material.
[0059] As shown in FIG. 1, in the information reproduction head
apparatus 100, a soft magnetic layer 15 is preferably provided for
facilitating formation of a magnetic loop. However, this soft
magnetic layer may not be provided. Moreover, as shown in FIG. 1A,
in the information reproduction head apparatus 100 of the resent
invention, the non-magnetic insulation layer 2 is preferably
embedded in the substrate 1. It is further preferable that another
non-magnetic insulation layer 21 be provided in the space between
the substrate surface and the magnetic pole 4 and in the space
below the tunnel junction element 5.
[0060] Alternatively, it is possible to omit the non-magnetic
insulation layer 2, using only the non-magnetic insulation layer
21. The magnetic pole 4 of the present invention is preferably
connected at least one of the upper electrode 6 and the lower
electrode 5 connected to the tunnel junction element. The magnetic
pole 4 may be in abutment with the respective electrodes, or may be
partially overlain.
[0061] More specifically, the magnetic pole 4 is preferably
constituted by a first magnetic pole 4-1 at a position where a
medium such as a disc is present and a second magnetic pole 4-2
located at an position with respect to the tunnel junction element
5.
[0062] A practical magnetoresitsance detection apparatus or a
magnetoresistance detection system can be obtained if the
information reproduction head apparatus 100 is added, for example,
by means (not depicted) for flowing current through the
magnetoresistance sensor 5 made from the tunnel junction element
and means (not depicted) for detecting a resistance change of the
magnetoresistance sensor as a function of the magnetic field
detected.
[0063] Description will now be directed to another example of the
present invention with reference to FIG. 6 and FIG. 7. An
information recording/reproduction system 200 includes: a magnetic
recording medium 53 having a plurality of tracks 52 for information
recording; a magnetic recording apparatus 47 having a lower
magnetic pole 43, a coil 41, and an upper magnetic pole 44 for
storing a predetermined information; and the aforementioned
information reproduction head apparatus 100 arranged on a substrate
42; and an actuator (not depicted) connected to the magnetic
recording apparatus 47 and to the information reproduction head
apparatus 100 for moving the magnetic recording apparatus 47 and
the information reproduction head 100 to a selected one of tracks
of the magnetic recording medium.
[0064] Hereinafter, a detailed explanation will be given on the
information reproduction head apparatus 100 of the present
invention.
[0065] That is, FIG. 1 is a cross sectional view and FIG. 2 is a
plan view of the information reproduction head apparatus 100
according to the present embodiment. The ferromagnetic substrate 1
is preferably made from NiZn ferrite, MnZn ferrite, MgZn ferrite,
or the like. As shown in FIG. 1, the ferromagnetic substrate 1 has
a groove 16, which is filled with the non-magnetic insulator 2. If
necessary, a non-magnetic insulation layer 21 is formed on this
non-magnetic insulator 2 and then the magnetoresistance effect
element 5, the upper and the lower electrode layers 6 and 7, and
the magnetic poles 4-1 and 4-2 are formed.
[0066] FIG. 10 is a plan view of the yoke type information
reproduction head apparatus 100 including the ferromagnetic tunnel
junction element 6 as follows.
[0067] That is, points A to L in FIG. 2 have film configurations as
follows.
[0068] A. A ferromagnetic substrate, a non-magnetic insulator, a
film thickness regulating layer, and a magnetic domain longitudinal
bias layer formed in this order.
[0069] B. The ferromagnetic substrate and the non-magnetic
insulator.
[0070] C. The ferromagnetic substrate.
[0071] D. The ferromagnetic substrate, the non-magnetic insulator,
and a magnetic pole.
[0072] E. The ferromagnetic substrate, the non-magnetic insulator,
a lower electrode film, and the magnetic domain control
longitudinal bias layer.
[0073] F. The ferromagnetic substrate.
[0074] G. The ferromagnetic substrate, a soft magnetic layer, and a
magnetic pole.
[0075] H. The ferromagnetic substrate, the non-magnetic insulation
layer, the magnetic pole.
[0076] I. The ferromagnetic substrate, the non-magnetic insulation
layer, the lower electrode film, a ferromagnetic tunnel junction
element, and an upper electrode film.
[0077] K. The ferromagnetic substrate, the non-magnetic insulator,
and a magnetic pole.
[0078] L. The ferromagnetic substrate, the non-magnetic insulation
layer, the lower electrode film, a ferromagnetic tunnel junction
element, and the magnetic pole.
[0079] Moreover, the respective film layers are preferably formed
using the following materials.
[0080] 1. Ferromagnetic substrate: NiZn ferrite, MnZn ferrite, MgZn
ferrite.
[0081] 2. Non-magnetic insulator: Al oxide, Si oxide, aluminum
nitride, silicon nitride, diamond-like carbon.
[0082] 3. Magnetic domain control longitudinal bias layer: CoCrPt,
CoCr, CoPt, CoCrTa, FeMn, NiMn, Ni oxide, NiCo oxide, IrMn, PtPdMn,
ReMn.
[0083] 4. Magnetic pole and soft magnetic layer: NiFe, CoZr, or
CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa, CoTaHf, CoNbHf,
CoZrNb, CoHfPd, CoTaZrNb, CoZrMoNi alloy, FeAlSi, iron nitride,
MnZn ferrite, NiZn ferrite, MgZn ferrite.
[0084] 5. Lower electrode film and upper electrode film: Au, Cu,
Mo, W, Ti.
[0085] 6. Film thickness regulating layer (layer inserted for
adjusting the position of the magnetic poles): Al oxide, si oxide,
aluminum nitride, silicon nitride, diamond-like carbon.
[0086] As has been described above, the longitudinal bias layer 8
according to the present embodiment may be arranged as shown in
FIG. 3 through FIG. 5.
[0087] That is, in FIG. 3, the longitudinal bias layer is arranged
in contact with the end portion of the ferromagnetic tunnel
junction element 5.
[0088] In FIG. 4, the longitudinal bias layer is arranged partially
overlain on the end portion of the ferromagnetic tunnel junction
element. In FIG. 5, the longitudinal bias layer is arranged
entirely on the ferromagnetic tunnel junction element.
[0089] In the yoke-type magnetoresistance effect information
reproduction head apparatus 100 according to the present
embodiment, the tunnel junction element used for the magnetic
sensor block 3 is as follows. The fixing layer has a function to
fix the magnetization direction of the fixed magnetic layer and is
contained as a part of the fixed magnetic layer 11.
[0090] Moreover, in the tunnel junction element 5 according to the
present embodiment, the aforementioned film layers are layered. The
arrangement of these layers may be other than that of FIG. 1. For
example, a reversed order may be used as will be described
later.
[0091] (1) substrate, undercoat layer, free magnetic layer,
non-magnetic layer, fixed magnetic layer, fixing layer, protection
layer
[0092] (2) substrate, undercoat layer, free magnetic layer, first
MR enhance layer, non-magnetic layer, fixed magnetic layer, fixing
layer, protection layer
[0093] (3) substrate, undercoat layer, free magnetic layer, first
MR enhance layer, non-magnetic layer, fixed magnetic layer, fixed
magnetic layer, fixing layer, protection layer
[0094] (4) substrate, undercoat layer, free magnetic layer, first
MR enhance layer, non-magnetic layer, second MR enhance layer,
fixed magnetic layer, fixing layer, protection layer
[0095] (5) substrate, undercoat layer, fixing layer, fixed magnetic
layer, non-magnetic layer, free magnetic layer, protection
layer
[0096] (6) substrate, undercoat layer, fixing layer, fixed magnetic
layer, first MR enhance layer, non-magnetic layer, free magnetic
layer, protection layer
[0097] (7) substrate, undercoat layer, fixing layer, fixed magnetic
layer, non-magnetic layer, second MR enhance layer, free magnetic
layer, protection layer
[0098] (8) substrate, undercoat layer, fixing layer, fixed magnetic
layer, first MR enhance layer, non-magnetic layer, second MR
enhance layer, free magnetic layer, protection layer
[0099] The aforementioned layers are preferably made from the
following materials.
[0100] (A) The undercoat layer may be a single layered film, mixed
film, or multi-film which is preferably made from a metal, oxide,
nitride.
[0101] More specifically, the undercoat layer (single layered film,
mixed film, multi-film) may be made from Ta, Hf, Zr, W, Cr, Ti, Mo,
Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au, Os, Pd, Nb, V or oxides
or nitrides of these materials.
[0102] Additionally, it is possible to use as an additive element
the following: Ta, Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co,
Zn, Ru, Rh, Re, Au, Os, Pd, Nb, V.
[0103] It should be noted that in this embodiment, the undercoat
may not be used.
[0104] (B) The free magnetic layer may be made from NiFe, CoFe,
NiFeCo, FeCo, CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa,
CoTaHf, CoNbHf, CoZrNb, CoHfPd, CoTaZrNb, CoZrMoNi alloys or
amorhpous magnetic material.
[0105] (C) The non-magnetic layer may be made from metal, oxide,
nitride, or mixture of oxide and nitride, or two-layered film of
metal and oxide, two-layered film of metal and nitride, or
two-layered film of metal and mixture of oxide and nitride.
[0106] For example, Ti, V, Cr, Co, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru,
Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Au, or oxide or nitride of
Si, Al, Ti, Ta as a single substance or mixture, or two-layered
film using the aforementioned oxide and nitride as a single
substance or mixture made from a single element or an alloy of Ta,
Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re, Au,
Os, Pd, Nb, V, Y.
[0107] (D) The first and the second MR enhance layers are
preferably formed by using Co, NiFeCo, FeCo and the like, or CoFeB,
CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa, CoTaHf, CoNbHf, CoZrNb,
CoHfPd, CoTaZrNb, CoZrMoNi alloy or amorphous materials.
[0108] In the present invention, when the MR enhance layer is not
provided, the MR ratio is slightly lowered, but the production
steps can be reduced.
[0109] (E) The fixed magnetic layer film may be made from a single
substance or alloy made from an element selected from a group
consisting of Co, Ni, and Fe, and the film may be layered.
[0110] (F) The fixing layer may be made from FeMn, NiMn, IrMn,
RhMn, PtPdMn, ReMn, PtMn, PtCrMn, CrMn, CrAl, TbCo, Ni oxide, Fe
oxide, mixutre of Ni oxide and Co oxide, mixture of Ni oxide and Fe
oxide, two-layered film made from Ni oxide and Co oxide,
two-layered film made from Ni oxide and Fe oxide, CoCr, CoCrPt,
CoCrTa, PtCo or the like.
[0111] Moreover, most effective candidate of the material is PtMn
or PtMn to which one of the following is added: Ti, V, Cr, Co, Cu,
Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt,
Au, Si, Al, Ti, and TA.
[0112] (G) The protection layer may be made from metal, oxide,
nitride, mixture of oxide and nitride, or two-layered film of metal
and oxide, two-layered film of metal and nitride, or two-layered
film of metal and mixture of the oxide and nitride. For example,
Ti, V, Cr, Co, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta,
W, Re, Os, Ir, Pt, Au; or oxide of a group consisting of Si, Al,
Ti, and Ta as a single substance or mixture; or a single substance
or alloy containing at least one element from a group consisting of
Ta, Hf, Zr, W, Cr, Ti, Mo, Pt, Ni, Ir, Cu, Ag, Co, Zn, Ru, Rh, Re,
Au, Os, Pd, Nb, V, and Y.
[0113] In the present embodiment, the yoke-type element 5 in
combination with the write head of an inductive coil can be used as
an information recording and reproducing system 200 as a unitary
block for recording and reproducing. FIG. 6 is a perspective view
of the information recording and reproducing system 200 employing
the recording and reproduction head according to the present
invention. The information recording and reproducing system 200
according to the present embodiment includes the information
reproduction head apparatus 100 according to the present invention
and a magnetic recording apparatus 47 which is an inductive type
recording head. In this example, a longitudinal magnetic recording
head is used, but the magnetoresistance effect element 5 according
to the present invention can also be used in combination with a
vertical magnetic recording head.
[0114] The magnetic recording apparatus 47 is an information
recording head including: a lower magnetic pole 43, a coil 41, and
an upper magnetic pole 44. The information reproduction head
apparatus 100 and the magnetic recording apparatus 47 are arranged
as shown in FIG. 6 and fixed to a base 42. Here, the upper shield
film of the information reproduction head 45 may also be used as
the lower magnetic pole of the recording head block 47, or the
upper shield and the lower magnetic pole may be produced
separately. This head writes a signal on the recording medium 53
and reads out a signal from the recording medium 53. As shown in
FIG. 6, the sensor portion of the reproduction head and the
magnetic gap of the recording head are formed on the same slider
and accordingly, it is possible to perform simultaneous positioning
on the same rack. This head is processed into a slider and mounted
on the information recording and reproducing system including the
magnetic recording reproduction apparatus.
[0115] FIG. 7 shows a concept of the magnetic recording and
reproduction apparatus using the magnetoresistance effect element
according to the present embodiment. The reproduction head 100 and
the recording head 47 are formed on the substrate 42 serving also
as a head slider. This is positioned on the recording medium 53 for
performing reproduction. The recording medium 53 is rotated, and
the head slider is relatively moved at the height of 0.2
micrometers above the recording medium 53 or in contact with the
recording medium 53.
[0116] Thus, the information reproduction 100 is arranged at a
position at which the magnetic signal recorded in the recording
medium 53 can be read from its leak magnetic field 54. Furthermore,
the information recording and reproducing system 200 according to
the present embodiment preferably includes a know actuator means
connected to the magnetic recording apparatus 47 and the
information reproduction head apparatus 100, so as to move the
magnetic recording apparatus 47 and the information reproducing
head apparatus 100 toward a selected track of the magnetic
recording medium 53. Hereinafter, further detailed explanation will
be given on the configuration, function, and operation method of
the information reproduction head apparatus 100. We prepared a
yoke-type information reproduction head apparatus 100 (conventional
example) without using the magnetic control longitudinal bias
layer.
[0117] The tunnel junction film was prepared by Ta (3 nm),
Pt.sub.46Mn.sub.54 (25 nm), Co.sub.90Fe.sub.10 (5 nm), aluminum
oxide (2 nm), Co.sub.90Fe.sub.10 (2 nm), Ni.sub.82Fe.sub.18 (8 nm),
and Ta (3 nm) .
[0118] After film formation, a thermal treatment was performed for
five hours at 250 degrees C in a direction vertical to the magnetic
field of film formation, while applying magnetic field of 500 Oe.
The components constituting the reproduction head had dimensions
shown in FIG. 8. The ferromagnetic substrate was MnZn ferrite. The
magnetic pole was formed by alternately forming a layer of Ta (5
nm) and Ni.sub.80Fe.sub.20 (20 nm) to obtain a total film thickness
of 200 nm. The non-magnetic insulator was made from Si oxide. The
lower electrode was made from Au (50 nm) sandwiched by Mo (5 nm).
The soft magnetic layer was prepared from Ni.sub.80Fe.sub.20. The
film thickness regulating layer was made from aluminum oxide.
[0119] As shown in FIG. 6, this head was processed into a recording
and reproduction unitary head together with a slider and a data was
recorded and reproduced to/from a CoCrTa medium. Here, the write
track width was 1.5 micrometers, the write gap was 0.2 micrometers,
and the read in track width was 1.0 micrometer. When preparing a
coil block of the write in head, the photoresist hardening step was
performed at temperature 250 degrees C for two hours.
[0120] During this process, the magnetization direction of the
fixed magnetic layer which should be directed in the element height
direction and the magnetization direction of the fixing layer were
rotated and normal operation as the magnetoresistance effect
element could not be obtained. For this, after the reproduction
head block and the recording head block were prepared, they were
subjected to one-hour magnetic thermal processing at 200 degrees C
in the magnetic field of 500 Oe.
[0121] Judging from the magnetization curve, this magnetization
thermal treatment did not rotate the magnetization direction of the
magnetization axis of the free magnetic layer. The coercive force
of the medium was set to 2.5 kOe.
[0122] The head thus prepared while changing the materials of the
magnetic domain longitudinal bias was used to measure a
reproduction output, S/N, mark length (frequency) for reducing the
reproduction output by half, and a bit error rate (See FIG.
10).
[0123] The reproduction output and the mark length reducing the
reproduction output by half are as large as 2.9 mV and 267 k,
respectively. This results in the S/N as low as 24 dB and the bit
error rate was only 1.times.10.sup.-4.
[0124] Next, the information reproduction head apparatus 100 as the
yoke type element shown in FIG. 1 and FIG. 2 was prepared using the
arrangement of the longitudinal bias 8 shown in FIG. 3.
[0125] The tunnel junction film of the information reproducing head
was constituted by Ta (3 nm), Pt.sub.46Mn.sub.54 (25 nm),
Co.sub.90Fe.sub.10 (5 nm), Al oxide (2 nm), Co.sub.90Fe.sub.10 (2
nm), Ni.sub.82Fe.sub.18 (8 nm), and Ta (3 nm).
[0126] After the film formation, the tunnel junction film was
subjected to a 5-hour thermal treatment while applying a magnetic
field of 500 Oe in a direction orthogonally intersecting the
magnetic field of film formation. The respective components
constituting the reproduction head used the dimensions shown in
FIG. 8.
[0127] The ferromagnetic substrate 1 was made from MnZn ferrite,
the magnetic poles (4-1, 4-2) was mad from alternating the Ta (5
nm) and the Ni.sub.80Fe.sub.20 (20 nm) so as to constitute a total
film thickness of 200 nm. The non-magnetic insulator 1 was made
from Si oxide. The lower electrode was made from Au (50 nm)
sandwiched by Mo (5 nm). The soft magnetic layer 15 was made from
Ni.sub.80Fe.sub.20. The film thickness regulating layer was made
from Al oxide.
[0128] As shown in FIG. 3, the magnetic domain control bias layer 8
is arranged so as to be in contact with the patterned film end. As
shown in FIG. 6, this head is processed into the
recording/reproducing unitary head with a slider. A data was
recorded and reproduced to/from a CoCrTa medium. The write-in track
width was set to 1.5 micrometers; the write-in gap was set to 0.2
micrometers; and the read-in track width was 1.0 micrometers.
[0129] When preparing a coil block 41 of the write-in head, the
photoresist hardening step was performed at temperature 250 degrees
C for two hours.
[0130] During this process, the magnetization direction of the
fixed magnetic layer which should be directed in the element height
direction and the magnetization direction of the fixing layer were
rotated and normal operation as the magnetoresistance effect
element could not be obtained. For this, after the reproduction
head block and the recording head block were prepared, they were
subjected to one-hour magnetic thermal processing at 200 degrees C
in the magnetic field of 500 Oe.
[0131] Judging from the magnetization curve, this magnetization
thermal treatment did not rotate the magnetization direction of the
magnetization axis of the free magnetic layer. The coercive force
of the medium was set to 2.5 kOe. The head was prepared with
different materials of the magnetic domain control bias layer to
measure a reproduction output, S/N, mark length (frequency) for
reducing the reproduction output by half, and a bit error rate (See
FIG. 11).
[0132] In comparison to the case (FIG. 10) using no magnetic domain
control longitudinal bias layer 8, in both cases (examples), the
reproduction output and the mark length reducing the reproduction
output by half were lowered. However, the reproduction waveform
became a preferable waveform with little Barkhausen noise. This
improved the S/N and the bit error rate to be
1.times.10.sup.-6.
[0133] Next, the information reproduction head apparatus 100 as the
yoke type element shown in FIG. 1 and FIG. 2 was prepared using the
arrangement of the longitudinal bias 8 shown in FIG. 4.
[0134] The tunnel junction film of the information reproducing head
was constituted by Ta (3 nm), Pt.sub.46Mn.sub.54 (25 nm),
Co.sub.90Fe.sub.10 (5 nm), Al oxide (2 nm), Co.sub.90Fe.sub.10 (2
nm), Ni.sub.82Fe.sub.18 (8 nm), and Ta (3 nm).
[0135] After the film formation, the tunnel junction film was
subjected to a 5-hour thermal treatment while applying a magnetic
field of 500 Oe in a direction orthogonally intersecting the
magnetic field of film formation. The respective components
constituting the reproduction head used the dimensions shown in
FIG. 8.
[0136] The ferromagnetic substrate 1 was made from MnZn ferrite,
the magnetic poles (4-1, 4-2) was mad from alternating the Ta (5
nm) and the Ni.sub.80Fe.sub.20 (20 nm) so as to constitute a total
film thickness of 200 nm. The non-magnetic insulator 2 was made
from Si oxide. The lower electrode was made from Au (50 nm)
sandwiched by Mo (5 nm). The soft magnetic layer 15 was made from
Ni.sub.80Fe.sub.20. The film thickness regulating layer was made
from Al oxide.
[0137] As shown in FIG. 4, the magnetic domain control bias layer 8
is arranged so as to be partially overlain on the patterned film
end. As shown in FIG. 6, This head is processed into the
recording/reproducing unitary head 200 with a slider. A data was
recorded and reproduced to/from a CoCrTa medium. The write-in track
width was set to 1.5 micrometers; the write-in gap was set to 0.2
micrometers; and the read-in track width was 1.0 micrometers.
[0138] When preparing a coil block 41 of the write in head, the
photoresist hardening step was performed at temperature 250 degrees
C for two hours.
[0139] During this process, the magnetization direction of the
fixed magnetic layer which should be directed in the element height
direction and the magnetization direction of the fixing layer were
rotated and normal operation as the magnetoresistance effect
element could not be obtained. For this, after the reproduction
head block and the recording head block were prepared, they were
subjected to one-hour magnetic thermal processing at 200 degrees C
in the magnetic field of 500 Oe.
[0140] Judging from the magnetization curve, this magnetization
thermal treatment did not rotate the magnetization direction of the
magnetization axis of the free magnetic layer. The coercive force
of the medium was set to 2.5 kOe. The magnetic domain control
longitudinal bias layer was made from different materials, and the
head was measured in reproduction output, S/N, mark length
(frequency) reducing the reproduction output by half, and the bit
error rate (FIG. 12).
[0141] In comparison to the case (FIG. 10) using no magnetic domain
control longitudinal bias layer 8, in respective cases (examples),
the reproduction output and the mark length reducing the
reproduction output by half were lowered. However, the reproduction
waveform became a preferable waveform with little Barkhausen noise.
This improved the S/N and the bit error rate to be
1.times.10.sup.-6.
[0142] Furthermore, using the configuration of FIG. 5 was used to
prepare the yoke type element 100 as shown in FIG. 1 and FIG.
2.
[0143] The tunnel junction film of the information reproducing head
was constituted by Ta (3 nm), Pt.sub.46Mn.sub.54 (25 nm),
Co.sub.90Fe.sub.10 (5 nm), Al oxide (2 nm), Co.sub.90Fe.sub.10 (2
nm), Ni.sub.82Fe.sub.18 (8 nm), and Ta (3 nm).
[0144] After the film formation, the tunnel junction film was
subjected to a 5-hour thermal treatment while applying a magnetic
field of 500 Oe in a direction orthogonally intersecting the
magnetic field of film formation.
[0145] The respective components constituting the reproduction head
used the dimensions shown in FIG. 9.
[0146] The ferromagnetic substrate 1 was made from MnZn ferrite,
the magnetic poles was made from alternating the Ta (5 nm) and the
Ni.sub.80Fe.sub.20 (20 nm) so as to constitute a total film
thickness of 200 nm. The non-magnetic insulator 1 was made from Si
oxide. The lower electrode was made from Au (50 nm) sandwiched by
Mo (5 nm). The soft magnetic layer 15 was made from
Ni.sub.80Fe.sub.20. The film thickness regulating layer was made
from Al oxide.
[0147] As shown in FIG. 5, the magnetic domain control bias layer 8
was arranged so as to be totally overlain on the patterned film
end. As shown in FIG. 6, This head is processed into the
recording/reproducing unitary head 200 with a slider. Here, the
write-in track width was set to 1.5 micrometers, write-in gap was
set to 0.2 micrometers, and the read-in track width was set to 0.8
micrometers.
[0148] When preparing a coil block 41 of the write in head block
47, the photoresist hardening step was performed at temperature 250
degrees C for two hours.
[0149] During this process, the magnetization direction of the
fixed magnetic layer which should be directed in the element height
direction and the magnetization direction of the fixing layer were
rotated and normal operation as the magnetoresistance effect
element could not be obtained. For this, after the reproduction
head block and the recording head block were prepared, they were
subjected to one-hour magnetic thermal treatment at 200 degrees C
in the magnetic field of 500 Oe.
[0150] Judging from the magnetization curve, this magnetization
thermal treatment did not rotate the magnetization direction of the
magnetization axis of the free magnetic layer. The coercive force
of the medium was set to 2.5 kOe. The magnetic domain control
longitudinal bias layer was made from different materials, and the
head was measured in reproduction output, S/N, mark length
(frequency) reducing the reproduction output by half, and the bit
error rate (FIG. 13).
[0151] In comparison to the case (FIG. 10) using no magnetic domain
control longitudinal bias layer 8, in respective cases (examples),
the reproduction output and the mark length reducing the
reproduction output by half were lowered. However, the reproduction
waveform became a preferable waveform with little Barkhausen noise.
This improved the S/N and the bit error rate to be
1.times.10.sup.-6 below.
[0152] Description will now be directed to a magnetic disc
apparatus as a specific example of the information recording and
reproducing system 200.
[0153] For example, the magnetic disc apparatus includes three
magnetic discs mounted on a base (not depicted). The back surface
of the base has a head drive circuit and signal processing circuit
as well as I/O interface. Here, a 32-bit bus line is used for
external connection. There are arranged six heads for both sides of
the optical discs. A rotary actuator for driving the heads, a drive
and control circuit, a directly connected spindle motor for disc
rotation are mounted on the magnetic disc apparatus 200. The disc
diameter is, for example, 46 mm, and the data surface is from 10 mm
to 40 mm.
[0154] The apparatus uses an embedded servo system having no servo
surface. This enables to obtain a high density.
[0155] This apparatus can be directly connected as an external
storage apparatus of a small-size computer. The I/O interface
includes a cache memory and can be connected by a bus line having a
transfer rate of 5 to 20 mega bytes per second. Moreover, by using
an external controller, a plurality of the present apparatus can be
connected so as to constitute a large capacity magnetic disc
apparatus.
[0156] [Embodiment 2]
[0157] Hereinafter, a detailed explanation will be given on the
information reproduction head apparatus and the information
recording/reproducing system according to the second embodiment of
the present invention with reference to the attached drawings.
[0158] FIG. 14 is a cross sectional view of a specific example of
the information reproduction head apparatus 100 including a
substrate 1 on which a magnetic sensor block 3 is provided via a
non-magnetic insulation layer 2. The magnetic sensor block 3 is
connected to a yoke block 14. That is, the information reproduction
head apparatus 100 is a yoke type information reproduction head 100
wherein the magnetic sensor block 3 is constituted by a
ferromagnetic tunnel junction element 5 sandwiched by an upper
electrode block 6 and a lower electrode block 7. The tunnel
junction element 5 is sandwiched by a front yoke block 14-1
adjacent to the medium 53 and a rear yoke block 14-2. At least a
part of the front yoke block 14-1 and at least a part of the lower
electrode 7 oppose to each other via the tunnel junction element 5.
That is, in this embodiment, it is preferable that the tunnel
junction element 5 be partially sandwiched by a part of the front
yoke block 14-1 and a part of the lower electrode 7.
[0159] On the other hand, as shown in FIG. 16, the junction surface
20 between the front yoke block 14-1 and the tunnel junction
element 5 be tapered. Moreover, as shown in FIG. 15, the front yoke
block 14-1 have a stepped configuration so as to be engaged with
the tunnel junction element 5.
[0160] Furthermore, in this embodiment, it is preferable that the
magnetic domain control bias layer 8 be provided in the direction
orthogonally intersecting the yoke block 14.
[0161] According to the present invention, the information
recording/reproducing system 200 includes: a magnetic recording
medium; a magnetic recording apparatus for recording an information
item on the recording medium; the aforementioned information
reproduction head apparatus 100; and actuator means (not depicted)
connected to the magnetic recording apparatus and the information
reproduction head apparatus 100 for moving the magnetic recording
apparatus and the information reproduction head 100 toward a
selected track of the magnetic recording medium 53.
[0162] Hereafter, a detailed explanation will be given on the
configuration of the information reproduction head apparatus 100
with reference to FIG. 14 to FIG. 17. In each of these example, a
part of the tunnel junction element 5 is sandwiched by at least a
part of the front yoke block 14-1 and at least a part of the lower
electrode 7.
[0163] The ferromagnetic substrate 1 (made from NiZn ferrite, MnZn
ferrite, MgZn ferrite or the like) has a groove 16. This groove 16
is filled with a non-magnetic insulator 2 (made from Al oxide, Si
oxide, aluminum nitride, silicone nitride, diamond-like carbon or
the like). This non-magnetic insulator 2 is covered with a
non-magnetic insulation layer 21, a magnetoresistance effect
element 5, upper and lower electrodes 6 and 7, and yoke block
14.
[0164] Referring to FIG. 18, film configuration of points A to N
are as follows.
[0165] A. ferromagnetic substrate, non-magnetic insulator, lower
electrode layer
[0166] B. ferromagnetic substrate, non-magnetic insulator, lower
electrode layer, magnetic domain control longitudinal bias
layer
[0167] C. ferromagnetic substrate, non-magnetic insulator
[0168] D. ferromagnetic substrate
[0169] E. ferromagnetic substrate, non-magnetic insulation layer,
front yoke layer
[0170] F. ferromagnetic substrate, non-magnetic insulator,
nonmagnetic insulation layer, front yoke layer
[0171] G. ferromagnetic substrate, non-magnetic insulation layer,
lower electrode layer, ferromagnetic tunnel junction element, upper
electrode layer
[0172] H. ferromagnetic substrate, non-magnetic insulation layer,
lower electrode layer, ferromagnetic tunnel junction element, front
yoke layer
[0173] I. ferromagnetic substrate, non-magnetic insulation layer,
rear yoke layer
[0174] J. ferromagnetic substrate, soft magnetic layer, rear yoke
layer
[0175] K. ferromagnetic substrate, non-magnetic insulator,
nonmagnetic insulation layer, rear yoke layer
[0176] L. feerromagnetic substrate, non-magnetic insulator, lower
electrode film, ferromagnetic tunnel junction element, rear yoke
layer
[0177] M. ferromagnetic substrate, non-magnetic insulator, film
thickness regulating layer, magnetic domain longitudinal bias
layer, upper electrode layer
[0178] N. ferromagnetic substrate, non-magnetic insulator, film
thickness regulating layer, upper electrode layer
[0179] Moreover, the respective film layers are preferably formed
using the following materials.
[0180] 1. Ferromagnetic substrate: NiZn ferrite, MnZn ferrite, MgZn
ferrite.
[0181] 2. Non-magnetic insulator: Al oxide, Si oxide, aluminum
nitride, silicon nitride, diamond-like carbon.
[0182] 3. Magnetic domain control longitudinal bias layer: CoCrPt,
CoCr, CoPt, CoCrTa, FeMn, NiMn, Ni oxide, NiCo oxide, IrMn, PtPdMn,
ReMn, PtPn.
[0183] 4. Yokke layer and soft magnetic layer: NiFe, CoZr, or
CoFeB, CoZrMo, CoZrNb, CoZr, CoZrTa, CoHf, CoTa, CoTaHf, CoNbHf,
CoZrNb, CoHfPd, CoTaZrNb, CoZrMoNi alloy, FeAlSi, iron nitride,
MnZn ferrite, NiZn ferrite, MgZn ferrite.
[0184] 5. Lower electrode film and upper electrode film: Au, Ag,
Cu, Mo, W, Ti.
[0185] 6. Film thickness regulating layer (layer inserted for
adjusting the position of the magnetic poles): Al oxide, si oxide,
aluminum nitride, silicon nitride, diamond-like carbon.
[0186] As has been described above, the longitudinal bias layer 8
according to the present embodiment may be arranged as shown in
FIG. 3 through FIG. 5, in the same way as the first embodiment.
[0187] The ferromagnetic tunnel junction element used in the
present embodiment may be as shown in FIG. 14B or such explained in
the first embodiment.
[0188] It should be noted that in the magnetic sensor 3 of this
information reproduction head apparatus 100, the fixing layer of
the tunnel junction element 5 has a function to fix the
magnetization direction of the fixed magnetic layer 11 and is
contained as a part of the fixed magnetic layer 11 in FIG. 14B.
Moreover, the tunnel junction element 5 according to the present
embodiment may have aforementioned respective layers on the
substrate arranged in the order as shown in FIG. 14 or in the
reversed order. In this embodiment, by forming a write-in head
block, the yoke type element 5 can be made into a
recording/reproducing unitary head, i.e., an information
recording/reproducing system 200.
[0189] FIG. 6 and FIG. 7 are perspective views of the information
recording/reproducing system 200 according to the present
embodiment.
[0190] Hereinafter, a detailed explanation will be given on the
information reproduction head apparatus 100 according to the
present embodiment.
[0191] That is, we prepared yoke type elements as shown in FIG. 14
to FIG. 17.
[0192] The tunnel junction film was prepared by Ta (3 nm),
Pt.sub.46Mn.sub.54 (25 nm) , Co.sub.90Fe.sub.10 (5 nm), aluminum
oxide (2 nm) , Co.sub.90Fe.sub.10 (2 nm) , Ni.sub.82Fe.sub.18 (8
nm) , and Ta (3 nm)
[0193] After film formation, a thermal treatment was performed at
250 degrees C for five hours in a direction vertical to the
magnetic field of film formation, while applying magnetic field of
500 Oe. The longitudinal bias made from 500 nm of CoCrTa was
arranged as in FIG. 3.
[0194] The components constituting the reproduction head had
dimensions shown in FIG. 19. The ferromagnetic substrate was made
from MnZn ferrite. The front yoke and the rear yoke were formed by
alternately forming a layer of Ta (5 nm) and Ni.sub.80Fe.sub.20 (20
nm) to obtain a total film thickness of 200 nm.
[0195] The non-magnetic insulator was made from Si oxide. The lower
electrode was made from Au (50 nm) sandwiched by Mo (5 nm) . The
soft magnetic layer was prepared from Ni.sub.80Fe.sub.20, and the
film thickness regulating layer was made from Zl oxide.
[0196] This head was made into a recording/reproducing unitary head
with a slider as shown in FIG. 6. and a data was recorded and
reproduced to/from a CoCrTa medium.
[0197] Here, the write-in track width was set to 1.5 micrometers;
the write-in gap was set to 0.2 micrometers; and the read-in width
was set to 0.7 micrometers. The coil portion of the write-in head
was prepared by the photoresist hardening step at 250 degrees C for
2 hours.
[0198] This step rotated the magnetization direction of the fixed
magnetic layer which should be orientated in the element height
direction and the magnetization of the fixing layer, disabling to
operate as a magnetoresistance element. For this, after preparing
the reproduction head block and the recording head block, one-hour
magnetization thermal treatment was performed at 200 degrees C, in
the magnetic field of 500 Oe.
[0199] From the magnetization curve, almost no rotation of the
magnetization axis of the free magnetic layer was observed. The
coercive force of the medium was 2.8 kOe. The head thus prepared
was used to check the reproduction output, S/N, the mark length
(frequency) reducing the reproduction output by half, and the bit
error rate.
[0200] Check results were preferable as follows.
[0201] In case of FIG. 14: reproduction output was 2.9 mV; mark
length reducing the reproduction output by half was 210 kFCI, S/N
was 34 dB, and the bit error rate was 1.times.10.sup.-6 or
less.
[0202] In case of FIG. 15: reproduction output was 3.2 mV; mark
length reducing the reproduction output by half was 267 kFCI, S/N
was 35 dB, and the bit error rate was 1.times.10.sup.-6 or
less.
[0203] In case of FIG. 16: reproduction output was 3.3 mV; mark
length reducing the reproduction output by half was 254 kFCI, S/N
was 37 dB, and the bit error rate was 1.times.10.sup.-6 or
less.
[0204] In case of FIG. 17: reproduction output was 3.4 mV; mark
length reducing the reproduction output by half was 259 kFCI, S/N
was 37 dB, and the bit error rate was 1.times.10.sup.-6 or
less.
[0205] The information reproduction head apparatus and the
information recording/reproducing system according to the first
embodiment having the aforementioned configuration can reduce the
reproduction waveform noise more than the conventional apparatus
and enables to obtain a preferable S/N and a preferable bit
rate.
[0206] The information reproduction head apparatus and the
information recording/reproducing system according to the second
embodiment having the aforementioned configuration wherein the
front yoke and the lower electrode are located not to interfere
each other. Thus, it is possible to realize a yoke type
magnetoresistance effect element assuring both of the front yoke
magnetic path and the lower electrode electric path.
[0207] The invention may be embodied in other specific forms
without departing from the spirit or essential characteristic
thereof. The present embodiments are therefore to be considered in
all respects as illustrative and not restrictive, the scope of the
invention being indicated by the appended claims rather than by the
foregoing description and all changes which come within the meaning
and range of equivalency of the claims are therefore intended to be
embraced therein.
[0208] The entire disclosure of Japanese Patent Application
(unexamined) No. 10-247093 (Filed on Sep. 1st, 1998) and Japanese
Patent Application (unexamined) No. 10-247095 (Filed on Sep. 1st,
1998) including specification, claims, drawings and summary are
incorporated herein by reference in its entirety.
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