JP4066839B2 - Thermally assisted magnetic recording head and thermally assisted magnetic recording apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermally assisted magnetic recording head and a thermally assisted magnetic recording apparatus, and more particularly to providing a thermally assisted magnetic recording head and a thermally assisted magnetic recording apparatus that can reduce the number of manufacturing steps, and can achieve high density and high speed.
[0002]
[Prior art]
In a hard disk device that performs recording / reproduction using a magnetic recording layer, a magnetoresistive sensor using a magnetoresistive effect for reproduction, that is, an MR (Magnetoresistive) sensor, or a GMR (Giant-magnetoresistive) sensor (higher sensitivity / high resolution) ( Since magnetoresistive sensors (hereinafter collectively referred to as “GMR sensors”) have been developed, high density has been achieved over the past few years at an annual rate of 60%. However, since the SuperPara-magnetic effect, that is, the magnetization direction of a certain magnetic domain is reversed by the adjacent magnetization in the opposite direction based on thermal disturbance, the surface density is limited to about 40 Gbits / inch ^2. (T. Rausch, Trans. Of MAGNETICS Society of Japan, Vol. 2, 2002, p. 322). Thereafter, the anisotropy of the magnetic material was improved and a recording density exceeding 100 Gbit / inch ² was achieved, but the limit of the recording density due to the Super Para-magnetic effect has finally been seen.
[0003]
As an effective means for solving this problem, heat-assisted magnetic recording has been proposed (for example, see Patent Document 1).
[0004]
This heat-assisted magnetic recording head is a laminate of a semiconductor laser (optical waveguide), a thin-film magnetic transducer, and a GMR sensor. The magnetic film is heated by irradiating a laser beam from the semiconductor laser, and the magnetization intensity of the film is lowered. The recording is performed by applying a magnetic field by a thin film magnetic transducer. As a result, recording can be performed on a magnetic film having a high coercive force, and magnetization reversal at room temperature can be prevented. In this method, recording is performed on the heated part with a magnetic field, but if the recording is not cooled immediately after recording, the recorded part will be erased by a magnetic field in the opposite direction, so both the magnetic field and the heat distribution are steep. At the same time, it is necessary to match the positions of the two as much as possible.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-4504
[Problems to be solved by the invention]
However, according to the conventional heat-assisted magnetic recording head, since the semiconductor laser is laminated in addition to the thin film magnetic transducer and the GMR sensor, there is a problem that the lamination process is long and complicated, and it is difficult to reduce the cost. In addition, since it is difficult to match the light irradiation position and the magnetic field application position, it is not always possible to form a minute recording mark as high as the minute light spot, to increase the density, and to reduce the recording speed, etc. There is a problem.
[0007]
There has also been proposed a method in which a current circuit is provided on the opposite side of the thin film magnetic transducer from the GMR sensor, and the current circuit is energized and heated. In this case, the manufacturing process may be only circuit formation, and it is possible by adding a relatively short process, but there is still a problem that it is difficult to match the temperature distribution and the magnetic field distribution.
[0008]
Accordingly, it is an object of the present invention to provide a thermally assisted magnetic recording head and a thermally assisted magnetic recording apparatus that can reduce the number of manufacturing steps, and can achieve high density and high speed.
[0009]
[Means for Solving the Problems]
To achieve the above object, the present invention heats a magnetic recording medium to reduce the coercive force of the portion, and applies a magnetic field to the portion where the coercive force is reduced to record information. A thin film magnetic transducer for generating the magnetic field in a magnetic gap formed between two magnetic poles at the tip of the yoke, and heat is generated when at least one of the two magnetic poles is energized, A heat-assisted magnetic recording head is provided that is a heating element for heating the magnetic recording medium.
[0010]
When a heating element provided in the vicinity of the magnetic gap is energized, the heating element generates heat due to Joule heat, thereby heating the magnetic recording medium and reducing the coercive force. Information is recorded in the portion where the coercive force is reduced by the magnetic field from the magnetic gap. In this configuration, the leakage magnetic field generated in the magnetic gap and the generation position of the Joule heat generated in the heating element provided in the vicinity of the magnetic gap can be matched, and high-speed and high-density heat-assisted magnetic recording becomes possible.
[0011]
In this configuration, the leakage magnetic field generated in the magnetic gap and the generation position of the Joule heat generated in the heating element provided in the vicinity of the magnetic gap can be matched, and high-speed and high-density heat-assisted magnetic recording becomes possible.
[0012]
In order to achieve the above object, the present invention records information by heating a magnetic recording medium to reduce the coercive force of the portion and applying a magnetic field to the portion where the coercive force is reduced by a thin film magnetic transducer. A thermally assisted magnetic recording head, and scanning means for causing the thermally assisted magnetic recording head to fly over the magnetic recording medium, and the thin film magnetic transducer is formed between two magnetic poles at a tip of a yoke, A magnetic gap for generating a magnetic field , wherein at least one of the two magnetic poles is a heating element , and the heating means heats the vicinity of the magnetic gap by energizing the heating element A heat-assisted magnetic recording apparatus characterized by heating a medium is provided.
[0013]
This configuration uses a heat-assisted magnetic recording head in which the leakage magnetic field generated in the magnetic gap matches the position of the Joule heat generated in the heating element provided in the vicinity of the magnetic gap. It becomes possible.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a thermally-assisted magnetic recording head according to a first embodiment of the present invention, where (a) is a sectional view, (b) is a bottom view, and (c) is viewed from the S direction of (a). FIG. 2 is a schematic diagram of a thin film magnetic transducer in which a magnetic coil is omitted. The thermally-assisted magnetic recording head 1 includes a flying slider 2, a GMR sensor 3 stacked on the rear surface 2a of the flying slider 2, and a thin film magnetic transducer 4 stacked on the rear surface of the GMR sensor 3 and having a magnetic field generating function and a heat generating function. With.
[0015]
The flying slider 2 is made of AlTiC (Al ₂ O ₃ —TiO ₂ ) used for a heat-assisted magnetic recording head of a hard disk drive, and includes a recess 2c and a floating surface 2b. The air bearing surface 2b is provided with three air bearing surfaces 21 so as to float on the magnetic recording layer 8a formed on the substrate 8b of the magnetic disk 8.
[0016]
The GMR sensor 3 is sandwiched between a spin valve film 31 having a magnetoresistive effect and a yoke 33 serving as a magnetic barrier film 32 and a magnetic barrier film via a dielectric layer 35, and supplies a pair of currents to the spin valve film 31. Electrodes 34 and 34 '. Since the magnetic barrier film 32 and the yoke 33 shield the stray magnetic field from entering the spin valve film 31, the leakage magnetic field from the magnetic recording layer 8a of the magnetic disk 8 is detected as a change in resistance of the spin valve film 31, and a signal is detected. Playback can be performed.
[0017]
The thin film magnetic transducer 4 includes a magnetic circuit constituted by yokes 33 and 43 and magnetic poles 40 and 41 at the tips thereof, a magnetic coil 44 linked to the magnetic circuit, and a magnetic gap between the magnetic poles 40 and 41. Connected to the magnetic coil 44, a spacer 42 as a heating element that fills the magnetic poles 40, dielectrics 45, 45 ′ made of a thin film having a thickness of 0.04 nm such as SiO ₂ that electrically insulates the magnetic poles 40, 41 and the spacer 42. The copper wiring 47 ′ and the electrode 49, and the copper wiring 47 and the electrode 48 connected to the spacer 42 are provided. The thin film magnetic transducer 4 heats the spacer 42 by applying a current to the spacer 42, generates a leakage magnetic field by flowing a current based on the recording signal to the magnetic coil 44, and heats the magnetic recording layer 8 a of the magnetic disk 8. In addition, recording is performed.
[0018]
Since the magnetic poles 40 and 41 become non-magnetic when the Curie temperature is exceeded, a material having a high Curie temperature, for example, 45 permalloy is used.
[0019]
The spacer 42 is a non-magnetic material and is made of a material having high electrical resistance and high heat resistance, such as tantalum (volume resistivity: 16.7 μΩ-cm), and the spacer 42 is low resistance made of copper. Are connected in a direction perpendicular to the direction of the yokes 33 and 43. When the length of the spacer 42 in the energizing direction is 0.06 μm and the cross section is 0.04 × 0.1 μm, the resistance value of the spacer 42 is 42Ω. When a current of 5 mA is applied to this portion at 1 Gbps, the spacer 42 can be heated to 300 ° C. or higher even if heat conduction is taken into consideration. The spacer 42 brings the heated portion of the spacer 42 closer to the air bearing surface 21 of the flying slider 2 and also the bottom surfaces of the wirings 47 and 47 closer to the air bearing surface 21 in order to increase the heating effect on the recording medium. Form.
[0020]
Next, an example of a method for manufacturing the heat-assisted magnetic recording head 1 will be described. The wafer used as the flying slider 2 is made of AlTiC (Al ₂ O ₃ —TiO ₂ ) used in the above-described heat-assisted magnetic recording head of the hard disk drive, and the GMR sensor 3 is an ordinary GMR (Giant Magnetic Sensor). Use. A GMR sensor 3 is formed by sequentially stacking yokes 32 and 33, electrodes 34 and 34 ', and a spin valve film 31 in a one-dimensional or two-dimensional manner on an Altic wafer via a dielectric layer 35. Further, the thin film magnetic transducer 4 is formed by laminating the magnetic coil 44, the yoke 43, and the like and fixing them with a dielectric spacer 46. A chip bar in which the GMR sensor 3 and the thin film magnetic transducer 4 are arranged one-dimensionally is cut out, and the cross section is processed as the floating surface 2b of the floating slider 2, and then cut into each head chip.
[0021]
Next, the operation of the thermally assisted magnetic recording head 1 according to the first embodiment will be described. The heat-assisted magnetic recording head 1 floats on the magnetic recording layer 8 a formed on the substrate 8 b of the magnetic disk 8 by the flying surface 2 b having the recess 2 c of the flying slider 2. When a current is passed through the spacer 42 via the electrode 48 and the copper wiring 47 of the thin film magnetic transducer 4, the spacer 42 generates heat, thereby heating the magnetic recording layer 8a and reducing the coercive force. When a current based on the recording signal is supplied to the magnetic coil 44 of the thin film magnetic transducer 4, a magnetic field proportional to the current is generated in the magnetic gap. Information is recorded in the portion where the coercive force of the magnetic recording layer 8a is reduced by the modulation of the magnetic field. The reproduction of the signal is performed by detecting a change in the strength of the magnetic field from the magnetic recording layer 8 a interlinked with the spin valve film 31 as a change in the resistance of the spin valve film 31.
[0022]
According to the first embodiment described above, the following effects can be obtained.
(1) When energizing 5 mA at 1 Gbps, the spacer 42 can be heated to 300 ° C. or higher, so that the coercive force of the magnetic recording layer 8 a can be lowered to the extent that recording can be performed with the thin film magnetic transducer 4. For example, when a TbFeCo magneto-optical recording medium is used for the magnetic recording layer 8a, it can be sufficiently heated to the Curie temperature, and recording can be performed with a low magnetic field. Even in the case of a magnetic material such as CoCr having a high Curie temperature of several hundred degrees, the coercive force can be lowered to such an extent that it can be recorded by the thin film magnetic transducer 4 by being heated.
(2) Since the heat-assisted magnetic recording head 1 of the present embodiment is mainly for in-plane recording, the magnetic gap width is narrow and the leakage magnetic field in the magnetic gap is used for recording on the magnetic recording medium. However, it can also be used for perpendicular magnetic recording.
[0023]
In addition, even if the spacer 42 has a low electrical resistance, such as molybdenum or tungsten, a spacer that can increase the resistance by reducing the film thickness and width can be used.
[0024]
FIG. 3 shows a main part of a thermally-assisted magnetic recording head according to the second embodiment of the present invention. This heat-assisted magnetic recording head 1 is a head for magnetic perpendicular magnetic recording, and only the thin film magnetic transducer 4 is different from the first embodiment, and the flying slider 2 and the GMR sensor 3 are the same as those in the first embodiment. Since these are the same, the description thereof is omitted. This thin-film magnetic transducer 4 has wirings 47 and 47 connected to one magnetic pole 41 ′ as a heating element. This is because the wiring is connected to the spacer 42 from the direction perpendicular to the magnetic circuit in FIG. 1, and the wiring 47, 47 is connected to the magnetic pole 41 ′ from the direction perpendicular to the magnetic circuit. Here, since the magnetic pole 41 'is required to have high heat resistance, the magnetic pole 41' is made of a material having a relatively high Curie temperature and a high electrical resistance, for example, 45 permalloy.
[0025]
According to the second embodiment, since the magnetic pole 41 ′ itself can be heated, the heat generation place and the magnetic field position can be exactly matched, and high-speed recording is possible. Further, by providing wirings 47 and 47 on the magnetic pole 41 of the conventional thin film magnetic transducer 4, the heat-assisted magnetic recording head 1 of this embodiment can be easily manufactured.
[0026]
4A and 4B show a thermally-assisted magnetic recording head according to the third embodiment of the present invention. FIG. 4A is a sectional view and FIG. 4B is a bottom view. In this heat-assisted magnetic recording head 1, the thin film magnetic recording transducer 4 is different from that of the first embodiment, and the flying slider 2 and the GMR sensor 3 are the same as those of the first embodiment, so that the description thereof is omitted. .
[0027]
The thin film magnetic transducer 4 includes a yoke 43 having a single magnetic pole 41 at the tip, yokes 33 and 33 ′ also serving as a magnetic barrier film, and two magnetic coils 44 and 44 ′. A magnetic circuit is configured through a soft magnetic film laid under the magnetic recording layer 8a. Reference numeral 43b denotes a connection yoke for connecting the three yokes 33, 33 ', 43.
[0028]
The yokes 33 and 33 ′ are installed on both sides of the single magnetic pole 41 in order to avoid the single magnetic pole 41 from being affected by the stray magnetic field. Accordingly, one magnetic coil 44 ′ is wound in the opposite direction with respect to the other magnetic coil 44 so that the direction of magnetization of the yokes 33, 33 ′ is opposite to that of the single magnetic pole 41.
[0029]
The distance between the single magnetic pole 41 and the other magnetic pole 40 is slightly separated to reduce the magnetic flux directly connected between them. If the distance is too large, it becomes difficult for the single magnetic pole 41 and the spin valve film 31 of the GMR sensor 3 to travel on the same track, so that the single magnetic pole 41 has a width of 0,06 μm. 3 μm. The single magnetic pole 41 forms a magnetic closed circuit with a soft magnetic film formed under the magnetic recording layer of a magnetic recording medium (not shown).
[0030]
Between the single magnetic pole 41 and the magnetic pole 40 of the yoke 33, as in the first embodiment, a spacer 42 made of a conductive material to which wirings 47 and 47 are connected is interposed via dielectrics 45 and 45 ′. The vicinity of the single magnetic pole 41 can be heated. The type, size, and the like of the conductive material of the spacer 42 are the same as those described in the first embodiment. This makes it possible to perform heat-assisted magnetic recording similar to that in the first embodiment by generating heat near the single magnetic pole 41.
[0031]
Next, the operation of the heat-assisted magnetic recording head 1 according to the third embodiment will be described. The heat-assisted magnetic recording head 1 floats on the magnetic recording layer 8 a formed on the substrate 8 b of the magnetic disk 8 by the flying surface 2 b having the recess 2 c of the flying slider 2. When a current is passed between the copper wirings 47 and 47, the spacer 42 generates heat, whereby the magnetic recording layer 8a is heated and the coercive force is lowered. When a current based on the recording signal is supplied to the magnetic coils 44 and 44 ′ of the thin film magnetic transducer 4, a magnetic field proportional to the current is generated in the magnetic gap. Information is recorded in the portion where the coercive force of the magnetic recording layer 8a is reduced by the modulation of the magnetic field. The reproduction of the signal is performed by detecting a change in the strength of the magnetic field from the magnetic recording layer 8 a interlinked with the spin valve film 31 as a change in the resistance of the spin valve film 31.
[0032]
According to the third embodiment, since the spacer 42 formed in the magnetic gap is energized from the direction perpendicular to the magnetic circuit, it is possible to generate heat in the vicinity of the single magnetic pole 41, and the heat generation location and the magnetic field position. Is effective for high-speed recording.
[0033]
In addition, by reducing the film thickness of the dielectric 45 ′ on the single magnetic pole 41 side, the spacer 42 and the single magnetic pole 41 can be brought close to each other, and the heat generation place and the magnetic field position can be made more coincident. , Stable recording becomes possible.
[0034]
FIG. 5 shows a main part of a thermally-assisted magnetic recording apparatus according to the fourth embodiment of the present invention. The heat-assisted magnetic recording apparatus 50 includes a magnetic disk 51 having a magnetic recording layer 51 ′, a motor 52 that rotates the magnetic disk 51, and a first, second, or second recording / reproducing on the magnetic recording layer 51 ′. , A swing arm 53 that scans the heat-assisted magnetic head 1, a linear motor 54 that operates the swing arm 53, a control circuit 70 that controls these, and a recording / reproducing signal And a signal processing circuit 80 for processing.
[0035]
The heat-assisted magnetic head 1 floats on the magnetic recording layer 51 ′ of the magnetic disk 51 rotated at a predetermined number of revolutions by the control circuit 70, and recording / reproduction is performed while following a predetermined recording track. Yes.
[0036]
For example, a TbFeCo film used for magneto-optical recording is used for the magnetic recording layer 51 ′ of the magnetic disk 51.
[0037]
Next, the operation of the heat-assisted magnetic recording apparatus 50 according to the fourth embodiment will be described. During recording, when a current is supplied to the spacer 42 based on the recording mark formation signal output from the signal processing circuit 80, the magnetic recording layer 51 ′ immediately below the magnetic pole 41 is heated to about 300 ° C. and simultaneously applied to the magnetic coil 44. A current based on the recording signal is applied to generate a magnetic field in the magnetic gap in which the spacer 42 is embedded, thereby forming a magnetic recording mark in the magnetic recording layer 51 ′.
[0038]
In order to perform stable recording, it is important to heat to the same temperature within the surface of the magnetic disk 51 and to rapidly cool the temperature of the magnetic recording layer 51 ′ to a level that does not affect the recording mark immediately after recording. For this purpose, the heating current is gradually increased from the inner circumference side toward the outer circumference side. At this time, although it varies depending on the disk structure and the recording medium, it can be heated to substantially the same temperature by increasing the square root of the peripheral speed in proportion to the first power. In addition, in order to rapidly cool after recording, a heating current is applied in a pulsed manner, and the timing is adjusted slightly earlier than the application of the magnetic field application current so that the magnetic field is applied when the temperature starts to decrease. . The degree of advancement varies depending on the rotational speed of the recording medium and the disk, but 10% to 50% of the pulse width is appropriate.
[0039]
According to the fourth embodiment, since the heat-assisted magnetic recording head in which the heat generation place and the magnetic field position are matched is used, recording can be performed even when a relatively weak magnetic field is applied. High-speed heat-assisted magnetic recording becomes possible. In addition, recording can be performed on a film having high magnetic anisotropy with a reduced coercive force.
[0040]
In the fourth embodiment, the number of disks is one, but a so-called Winchester type in which a plurality of disks are stacked may be used. Also, by making the heating current pulse application interval shorter than the magnetic field application pulse interval, the temperature of the magnetic recording layer 51 ′ can be rapidly cooled to a level that does not affect the recording mark immediately after recording.
[0041]
【The invention's effect】
As described above, according to the present invention, since the magnetic field generation position and the Joule heat generation position coincide, the recording mark can be miniaturized and the density can be increased. Also, since recording can be performed immediately after heating, the speed can be increased. Further, since the magnetic field generation and heat generation are performed by the thin film magnetic transducer, the number of parts can be reduced and the manufacturing process can be reduced.
[Brief description of the drawings]
FIG. 1 shows a thermally-assisted magnetic recording head according to a first embodiment of the present invention, where (a) is a cross-sectional view, (b) is a bottom view, and (c) is viewed from the S direction of (a). It is a rear view.
FIG. 2 is a schematic diagram of the thin film magnetic transducer according to the first embodiment of the invention.
FIG. 3 is a bottom view showing a thermally-assisted magnetic recording head according to a second embodiment of the invention.
4A and 4B show a thermally-assisted magnetic recording head according to a third embodiment of the present invention, where FIG. 4A is a cross-sectional view and FIG. 4B is a bottom view.
FIG. 5 is a schematic diagram showing the main part of a thermally-assisted magnetic recording apparatus according to a third embodiment of the invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat-assisted magnetic recording head 2 Floating slider 2a Rear surface 2b of floating slider 2c Floating surface 2c Recess 3 GMR sensor 4 Thin film magnetic transducer 8 Magnetic disk 8a Magnetic recording layer 8b Substrate 21 Air bearing surface 31 Spin valve film 32 Magnetic barrier films 33, 33 ', 43 Yoke 34, 34' Electrode 35 Dielectric layer 40 Magnetic pole 41 Single magnetic pole 42 Spacer 43b Connection yoke 44 Magnetic coil 45 Insulating film 46 Dielectric spacer 47, 47 'Copper wiring 48 Electrode 50 Thermally assisted magnetic recording device 51 Magnetic Disk 51 ′ Magnetic Recording Layer 52 Motor 53 Swing Arm 54 Linear Motor 70 Control Circuit 80 Signal Processing Circuit

Claims (9)

In a thermally assisted magnetic recording head that records information by applying a magnetic field to the portion where the coercive force is reduced by heating the magnetic recording medium to reduce the coercive force of the portion,
A thin film magnetic transducer for generating the magnetic field in a magnetic gap formed between two magnetic poles at the tip of the yoke;
Wherein at least one of the magnetic poles of the two magnetic poles, generates heat by being energized, the heat-assisted magnetic recording head which is a heating element for heating the magnetic recording medium.   The heat-assisted magnetic recording head according to claim 1, wherein the heating element is made of a high electrical resistance material. Wherein two heat-assisted magnetic recording head according to claim 2, wherein the dielectric between the magnetic pole is formed.   The heat-assisted magnetic recording head according to claim 1, wherein the heating element includes a wiring made of a low electrical resistance material for energization.   The thermally-assisted magnetic recording head according to claim 6, wherein the wiring is wired in a direction spatially orthogonal to the two magnetic poles. Heating means for heating the magnetic recording medium to reduce the coercive force of the portion;
A thermally assisted magnetic recording head for recording information by applying a magnetic field by a thin film magnetic transducer to the portion where the coercive force has decreased;
Scanning means for flying the thermally-assisted magnetic recording head over the magnetic recording medium,
The thin film magnetic transducer is formed between two magnetic poles of the tip of the yoke, a magnetic gap for generating the magnetic field, at least one magnetic pole of said two magnetic poles are heating elements,
The heat-assisted magnetic recording apparatus, wherein the heating unit heats the magnetic recording medium by energizing the heating element to heat the vicinity of the magnetic gap. Claim 6, wherein the heating means, characterized in that the energizing of the heating current to the heating current supplied to the heating element increases as to go from the inner periphery to the outer periphery of the magnetic recording medium to the heating element The heat-assisted magnetic recording apparatus described. 8. The heat-assisted magnetic recording apparatus according to claim 7 , wherein the heating means applies the heating current in a pulse form at a timing earlier than the timing of applying the magnetic field. 9. The heat-assisted magnetic recording apparatus according to claim 8 , wherein the heating means has a pulse width of the heating current applied in the form of pulses shorter than a current pulse width for applying a magnetic field.

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