JP2010257539A - Magnetic recording head and magnetic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-density information recording device having high reliability by stabilizing operation of a magnetization high-speed rotation body that generates high-frequency magnetic field, in microwave assist recording. <P>SOLUTION: A magnetization high-speed rotation body 2 is arranged at the vicinity of a main magnetic pole 5 that generates a magnetization inversion magnetic field, information is recorded by causing a recording medium 7 to magnetically resonate or to be magnetically inverted with a high frequency magnetic field generated from the magnetization high-speed rotation body. A mechanism for reducing a component applied to a magnetization rotation plane of the magnetization high-speed rotation body out of leakage magnetic field from the main magnetic pole applied to the magnetization high-speed rotation body, for example, a mechanism for tilting a main magnetic pole side plane so as to separate from the magnetization high-speed rotation body, is used. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention provides a magnetic recording head having a function of applying a recording magnetic field to a magnetic recording medium and irradiating a high-frequency magnetic field to excite magnetic resonance to induce magnetization reversal of the magnetic recording medium, and the magnetic recording head The present invention relates to a magnetic recording apparatus provided.

  In order to maintain a stable recording magnetization state in magnetic recording, it is necessary to use a recording medium having a large coercive force (that is, a large magnetic anisotropy), but in order to perform recording on a recording medium having a large coercive force. A strong recording magnetic field is required. However, in practice, the magnetic materials that can be used as the magnetic head are limited. Therefore, the coercive force of the recording medium is limited by the magnitude of the recording magnetic field that can be generated by the recording head. For this reason, a recording method has been devised in which the coercive force of the recording medium is effectively lowered only during recording using various auxiliary means, and heat-assisted recording is performed by using a magnetic head and a heating means such as a laser in combination. Such is the representative.

  There has been an idea for a long time to perform recording by locally reducing the coercive force of a recording medium by using a high-frequency magnetic field in combination with a recording magnetic field from a recording head. For example, Japanese Patent Laid-Open No. 6-243527 discloses a technique for recording information by locally reducing the coercive force of a magnetic recording medium by Joule heating or magnetic resonance heating with a high frequency magnetic field. In such a recording technique that uses magnetic resonance between a high-frequency magnetic field and a magnetic head magnetic field (hereinafter referred to as microwave-assisted recording), a high-frequency magnetic field having a strong frequency proportional to the medium anisotropic magnetic field is used because magnetic resonance is used. Otherwise, the effect of reducing a large magnetization reversal magnetic field cannot be obtained. It is very difficult to manufacture such a magnetic field generating element capable of generating a strong high-frequency magnetic field with a size that can be mounted on a magnetic head. Therefore, microwave-assisted recording is long due to difficulty in practical use. It was a forgotten technology.

  However, in recent years, the principle of generating a high-frequency magnetic field using spin torque has been proposed, and microwave assisted recording has come to the spotlight. In TMRC-B6 (2007), a magnetized high-speed rotating body (Field Generation Layer: FGL) that rotates at high speed by spin torque is disposed in the vicinity of a magnetic recording medium adjacent to a main magnetic pole of a perpendicular magnetic head, and a microwave (high-frequency magnetic field). The technology to record information on magnetic recording media with large magnetic anisotropy has been announced. Furthermore, in MMM-GA02 (2008), a high-frequency magnetic field generator that controls the rotation direction of the FGL by using the magnetic field of the main magnetic pole close to the FGL has been announced. It is said that inversion can be realized.

JP-A-6-243527

J. G. Zhu and X. Zhu, ‘Microwave Assisted Magnetic Recording,’ The Magnetic Recording Conference (TMRC) 2007 Paper B6 (2007). J. Zhu1 and Y. Wang, ‘Microwave Assisted Magnetic Recording with Circular AC Field Generated by Spin Torque Transfer,’ MMM Conference 2008 Paper GA-02 (2008).

  In order to realize a recording density exceeding 1 Tbit per square inch in microwave assisted recording, a magnetic field is recorded by irradiating a nanometer-order region to which a writing magnetic field from the main magnetic pole is applied. It is necessary to record the information by locally bringing the medium into a magnetic resonance state and reducing the magnetization reversal field.

  The technology disclosed in TMRC-B6 (2007) records information by irradiating a region of nanometer order with a strong high-frequency magnetic field to bring the recording medium into a local magnetic resonance state and reducing the magnetization reversal field. However, there is a problem that no consideration is given to the control of the magnetization of the FGL. Since a large high frequency magnetic field cannot be obtained unless the magnetization of the FGL is perpendicular to the rotation axis, it is difficult to obtain a high frequency magnetic field having a practical strength with the FGL configuration disclosed in TMRC-B6 (2007). is there.

  The technique disclosed in MMM-GA02 (2008) is a structure that controls the rotation direction of the FGL by using a magnetic field component that is vertically incident among the magnetic fields that are incident on the FGL from the main magnetic pole. The problem of magnetic field strength is solved. However, no countermeasure is taken against the leakage magnetic field from the main magnetic pole incident on the rotation plane of the FGL. Therefore, the technique disclosed in MMM-GA02 (2008) has a problem that the magnetization of the FGL is fixed in the direction of the leakage magnetic field from the main pole, and high-frequency oscillation does not continue.

  An object of the present invention is to provide an ultra-high-density magnet that is highly reliable and can reduce costs as a result by taking measures against a leakage magnetic field (hereinafter referred to as a transverse magnetic field) from a main magnetic pole incident on the rotation plane of the FGL. An object is to provide an information recording apparatus suitable for recording.

  For the purpose of solving the above problems, first, the extent to which the transverse magnetic field should be suppressed was examined by computer simulation. The behavior of the FGL magnetization m as shown in FIG. 1 was analyzed using the following equation (1) that takes into account the effect of spin torque on the LLG (Landau Lifschitz Gilbert) equation.

Here, γ is a gyro magnetic constant, α (assuming 0.01) is a damping constant, I is a current, μ _B is a Bohr magneton, e is an elementary charge, V is a volume of FGL, and M _s (= 1. 9T) is the magnetization of the FGL. The effective magnetic field H _eff is composed of the sum of three components: _a magnetic anisotropy magnetic field H _a (= H _k cos θ, θ is an angle formed by magnetization and an easy axis of magnetization), a demagnetizing field H _d , and an external magnetic field H _ext. . The easy axis of magnetization was the x-axis direction, and negative magnetic anisotropy (H _k = −800 kA / m) was assumed. Magnetization of FGL acts anisotropy field H _a is such that the plane (theta = 90 degrees). Further, the magnetization m _{1 of the} Polarization layer is oriented in the x direction and the polarizability P is 0.244. H _ext was applied in a direction inclined by θ _h from the x direction.

First, a simple steady state analytical solution is obtained. When θ _h = 0 degree, the expression (1) satisfies dm _x / dt = 0 because the x-direction component H _eff-x of the effective magnetic field H _eff

を満たすときで、このとき、磁化が周波数ｆでｘ軸の周りを回転運動する。

At this time, the magnetization rotates around the x-axis at the frequency f.

2πf = γH _eff-x (3)

This shows that H _eff-x increases and the frequency of the high-frequency magnetic field increases as the magnetic field applied perpendicular to the FGL surface increases. Therefore, the component perpendicular to the magnetization rotation plane of the FGL in the leakage magnetic field from the main pole effectively acts on the frequency improvement of the FGL. In order to obtain a high frequency magnetic field of 30 GHz, a magnetic field of about 800 kA / m is required.

  When the external magnetic field is tilted from the x-axis, it is necessary to investigate the behavior of magnetization by solving Equation (1) sequentially. FIG. 2 shows the behavior of FGL magnetization when an external magnetic field of 800 kA / m is tilted 15 degrees from the x direction. FIG. 2 (A) shows three-dimensionally the magnetization trajectory until 0.5 ns has passed since the application of the external magnetic field, and a stable rotation is obtained although the orbital plane is slightly inclined from the yz plane. ing. FIG. 2B shows a projection of magnetization on the yz plane until 2 ns have passed since the application of the external magnetic field, and stable rotation is obtained.

  FIG. 3 shows the behavior of FGL magnetization when an external magnetic field of 800 kA / m is tilted 25 degrees from the x direction. FIG. 3 (A) shows a three-dimensional magnetization trajectory until 0.5 ns has passed since the application of an external magnetic field. The orbital plane is slightly inclined from the yz plane, and the inclination is gradually increased with time. It is increasing. FIG. 3B shows the magnetization trajectory until 2 ns has passed since the application of the external magnetic field, projected onto the yz plane, and it can be seen that the trajectory contracts over time. This is presumably because the trajectory of FGL magnetization is constrained in the direction of the transverse magnetic field. From the above, it can be seen that when the external magnetic field is applied beyond 25 degrees from the x direction, the magnetization of the FGL does not rotate stably.

  Next, the magnetic field near the main magnetic pole was analyzed using a three-dimensional magnetic field simulator. FIG. 5 shows a three-dimensional magnetic field analysis performed under the conditions shown in FIG. 4 including the main magnetic pole 5, the counter magnetic pole 6, and the soft magnetic underlayer 22. SL in FIG. 4 is a rotation stabilization layer. It can be seen that a transverse magnetic field is applied to the portion where the FGL is installed. From the figure, it is estimated that the cause of this transverse magnetic field is mainly the leakage magnetic field from the opposite magnetic pole side surface of the main magnetic pole 5. From this, in order to prevent the FGL portion from being affected as much as possible by the opposing magnetic pole side surface of the main magnetic pole 5, (1) the height of the opposing magnetic pole is sufficiently higher than the height of the magnetized high-speed rotating body (FGL). It can be seen that a lateral magnetic field reduction configuration in which the main magnetic pole side surface is inclined so as to be away from the high-speed rotating body of magnetization, and (3) a bypass magnetic path is formed in the counter magnetic pole from the vicinity of the main magnetic pole side surface.

  FIG. 6 is a graph of the direction and magnitude of the magnetic field at the position where the FGL is installed from FIG. The horizontal axis in the figure is the position, and the height of the ABS surface is the origin and the recording medium direction is positive. In the figure, the range assuming the opposite magnetic pole is shown by hatching. As shown in FIG. 6A, when going from the ABS surface (position = 0) upward (position <0), the angle of the magnetic field once takes a local minimum value and then increases, and the end of the opposing magnetic pole (position = At −60 nm), it reaches 40 degrees. Further, from FIG. 6B, the magnetic field intensity increases upward from the ABS surface, and takes a maximum value of 1000 kA / m slightly before the end of the opposed magnetic pole.

  From the above, it is considered that when FGL having the same height as the range of the opposing magnetic pole is used, a stable magnetic rotation cannot be obtained due to an adverse effect of a large magnetic field angle. However, since the angle of the magnetic field is relatively small in the vicinity of the ABS surface, it is considered that stable FGL rotation can be obtained if the FGL height is sufficiently lower than the end of the opposing magnetic pole. In this calculation, considering that the interval between the main magnetic pole 5 and the counter magnetic pole 6 is assumed to be 40 nm, a margin more than half of the distance between the main magnetic pole 5 and the counter magnetic pole 6 (the FGL height and the end of the counter magnetic pole 6 If there is a difference, there is no problem. However, as the end portion of the counter magnetic pole becomes larger than the FGL height, the magnetic flux is absorbed by the counter magnetic pole 6 before reaching the tip of the main magnetic pole 5, so that the recording magnetic field from the main magnetic pole 5 becomes smaller. Therefore, it is not preferable.

  FIG. 8 is a graph showing the direction and magnitude of the magnetic field at the position where the FGL is installed, assuming a structure in which the main magnetic pole side surface of the transverse magnetic field reduction configuration (2) shown in FIG. 7 is tilted away from the FGL. Is. As shown in FIG. 8A, the angle of the magnetic field once takes a minimum value when going upward from the ABS surface, and then starts to increase in common with FIG. 6A. However, the magnetic field angle is within 25 degrees within the range of the opposing magnetic pole. Further, as shown in FIG. 8B, the magnetic field intensity increases upward from the ABS surface, and takes a maximum value of 1000 kA / m at the center of the counter magnetic pole. From the above, in the structure in which the main magnetic pole is tilted away from the FGL, the FGL in-plane direction component of the leakage magnetic field from the main magnetic pole is reduced, so that stable magnetization rotation of the FGL can be obtained. .

  FIG. 9 shows some positional relationships of the main magnetic pole 5, the high-frequency magnetic field generating element 201, and the counter magnetic pole 6 so that the FGL portion is not affected as much as possible by the side surface of the main magnetic pole 5 facing the counter magnetic pole. The arrow in the figure represents the magnetization direction. FIG. 9A shows a conventional structure in which a large leakage magnetic field from the side surface of the main magnetic pole 5 is applied in the FGL in-plane direction of the high-frequency magnetic field generating element 201, so that it is difficult to generate a stable high-frequency magnetic field. FIG. 9B is a transverse magnetic field reduction configuration in which the upper part in the element height direction of the connection portion of the main magnetic pole 5 of the above (2) with the high frequency magnetic field generating element 201 is inclined to the opposite side of the high frequency magnetic field generating element 201. As shown in FIG. 8, the magnetic field applied in the FGL in-plane direction is greatly reduced. Note that the method of inclining the side surface of the main magnetic pole (2) away from the high-speed rotating magnet is effective if the side surface of the main magnetic pole 5 on the high-frequency magnetic field generating element side is separated from the high-frequency magnetic field generating element 201. The angle of the flow of the magnetic flux passing through the main magnetic pole 5 as shown in FIG. 9G is near the connecting portion between the main magnetic pole 5 and the high-frequency magnetic field generating element 201 from the upper side in the element height direction to the opposite side of the high-frequency magnetic field generating element 201. It is also possible to adopt a configuration in which the transverse magnetic field is inclined to the angle.

  FIGS. 9C and 9D show a transverse magnetic field reduction configuration in which the height in the element height direction of the counter magnetic pole of (1) above is sufficiently higher than the height of the magnetized high-speed rotating body (FGL). The difference Ht between the height in the vertical direction and the height in the element height direction of the high-frequency magnetic field generating element 201 is preferably about 0.5 to 2 times the distance Lf between the main magnetic pole 5 and the counter magnetic pole 6.

  FIGS. 9E and 9F are transverse magnetic field reduction methods for forming the bypass magnetic path described in (3) above, in which a magnetic path is formed from the counter magnetic pole 6 toward the main magnetic pole 5 and from the side surface of the main magnetic pole 5. It works to release the leakage magnetic field. If the bypass magnetic path is in contact with the main magnetic pole 5, the magnetic flux is absorbed by the counter magnetic pole 6 before reaching the tip of the main magnetic pole 5, and the recording magnetic field from the main magnetic pole 5 becomes small.

  By adopting the above configuration, it becomes possible to reduce the leakage magnetic field component from the main magnetic pole applied in the FGL magnetization rotation plane, so that stable FGL rotation during the recording operation can be obtained, and Thus, a good recording pattern can be formed, the recording density in the information recording apparatus can be increased, and at the same time the reliability can be improved, and as a result, the cost can be reduced.

  An information recording apparatus having a recording density exceeding 1 Tbit per square inch can be realized, and at the same time, the reliability can be improved, and as a result, the cost can be reduced.

The figure which shows the magnetization rotation model of FGL. The figure which shows the magnetization rotation behavior of FGL. Another figure which shows the magnetization rotation behavior of FGL. The block diagram of the conventional head used for the magnetic field distribution analysis of the main magnetic pole vicinity. The figure which shows magnetic field distribution of the main magnetic pole vicinity. The graph which shows the magnetic field distribution near the main pole. The block diagram of the head of this invention used for the magnetic field distribution analysis of the main magnetic pole vicinity. The graph which shows the magnetic field distribution of the main magnetic pole vicinity of this invention. The figure which shows the leakage magnetic field reduction structure from the main pole of this invention. FIG. 3 is a diagram illustrating a configuration example of a magnetic head slider and a magnetic head. The enlarged view of a magnetic head part. The enlarged view of a recording head part. The figure which shows the magnetic head of the conventional structure made as an experiment. The figure which shows the example of a high frequency magnetic field generator structure. The enlarged view of a magnetic head part. FIG. 3 is a diagram illustrating a configuration example of a magnetic head slider and a magnetic head. The enlarged view of a magnetic head part. FIG. 6 is a configuration diagram (cross-sectional view) of a recording head unit according to a second embodiment. 1 is an overall configuration diagram of a magnetic disk device. The graph which shows the magnetic field distribution near the main pole.

  Hereinafter, the principle of generating a high-frequency magnetic field will be described with reference to FIGS. This principle is common to the embodiments described later.

  10 and 11 show the basic configuration of a magnetic head for microwave-assisted recording that includes a magnetization rotator, a spin rectifier, and a magnetic flux rectifier film.

  FIG. 10 is a diagram schematically showing the relative positional relationship between the magnetic head slider and the magnetic recording medium. The magnetic head slider 102 is supported by the suspension 106 so as to face the recording medium 101. In FIG. 10, it is assumed that the recording medium 101 rotates in the right direction on the paper surface, and the opposing magnetic head slider moves relative to the recording medium in the left direction on the paper surface. Therefore, in FIG. 10, the magnetic head portion 109 is arranged on the trailing side of the slider. The drive current of each component of the magnetic head unit 109 is fed by the wiring 108 and supplied to each component by the terminal 110.

  FIG. 11 is an enlarged view of the magnetic head unit 109 shown in FIG. The magnetic head unit 109 includes a recording head unit and a reproducing head unit. The recording head unit includes an auxiliary magnetic pole 206, a high-frequency magnetic field generating element 201 disposed between the main magnetic pole 5 and the counter magnetic pole 6, and a main magnetic pole. The coil 205 etc. which excites The reproducing head unit includes a reproducing sensor 207 disposed between the lower shield 208 and the upper shield 210. The auxiliary magnetic pole 206 and the upper shield 210 may be used in combination. Although not shown, the coil excitation current, the reproduction sensor drive current, and the applied current to the high-frequency magnetic field generating element are supplied from current supply terminals provided for each component.

  As shown in FIG. 11, the counter magnetic pole 6 extends toward the main magnetic pole 5 in the upper direction of the element height, and forms a magnetic circuit with each other. However, it is assumed that the upper part in the element height direction is electrically insulated. In the magnetic circuit, the magnetic lines of force form a closed circuit, and it is not necessary to be formed of only a magnetic material. In the figure, an auxiliary magnetic pole or the like is arranged on the opposite side of the main magnetic pole 5 from the counter magnetic pole 6 to form another magnetic circuit. In this other magnetic circuit, the main magnetic pole 5 and the auxiliary magnetic pole need not be electrically insulated. The main magnetic pole 5 and the counter magnetic pole 6 are provided with an electrode or a means for electrically contacting the electrode, and a high-frequency excitation current flowing from the main magnetic pole 5 side to the counter magnetic pole 6 side or in the opposite direction can flow through the magnetization rotator layer. It is configured as follows.

  FIG. 12 is an enlarged view of the recording head portion shown in FIG. A high frequency magnetic field generating element 201 is formed between the main magnetic pole 5 and the counter magnetic pole 6. Between the main magnetic pole 5 and the counter magnetic pole 6, a steady current flows in the direction of the black arrow, and the relative movement direction of the head is the direction indicated by the white arrow. As the magnetic recording medium 7, a medium in which the perpendicular recording film 16 is laminated on the substrate 19 through the underlayer 20 was used.

  The high-frequency magnetic field generating element 201 has a magnetic flux rectifying layer 8, a nonmagnetic spin scatterer 12, a magnetization rotation layer (FGL) 2, and a rotation stabilization layer (SL) from the air bearing surface end side surface of the main pole 5 toward the trailing side. ) 11, a negative perpendicular magnetic anisotropic layer, a metal nonmagnetic spin conductive layer 15, and a counter magnetic pole side magnetic flux rectifying layer 13, and a structure reaching the counter magnetic pole 6. Since the spontaneous magnetization of the rotation stabilizing layer (SL) 11 is stable in the laminated surface, a force is applied to keep the direction of the spontaneous magnetization of the magnetization rotating layer 2 in contact with the laminated surface in the laminated surface, and the rotation is stabilized. To do. The metal nonmagnetic spin scatterer layer 12 extends from the magnetic flux rectifying layer 8 to the magnetization rotator layer, which may affect the effect of the spin torque flowing into the magnetization rotator layer 2 via the metal nonmagnetic spin conductive layer 15. 2 has the effect of scattering the spins flowing into 2. Alternatively, it can be said that there is an effect of preventing the spin torque from flowing out from the magnetization rotator layer 2 to the magnetic flux rectifying layer 8. Therefore, when the metal nonmagnetic spin scatterer layer 12 is used, the current for obtaining the required spin torque can be reduced. This effect is particularly great when Ru is used as the metal nonmagnetic spin scatterer layer 12.

  When a current is passed through the laminated film having such a structure in the direction from the counter magnetic pole 6 to the main magnetic pole 5, electrons move from the main magnetic pole 5 to the counter magnetic pole 6 via each layer. Here, when the main magnetic pole 5 is excited downward, the magnetic flux rectifying layer 8 and the opposing magnetic pole side magnetic flux rectifying layer 13 are magnetized substantially rightward, so that only electrons having rightward spin are nonmagnetic spin conducting. It passes through the layer 15 and reaches the opposing magnetic pole side magnetic flux rectifying layer 13. Electrons having a leftward spin cannot pass through the opposed magnetic pole side magnetic flux rectifying layer 13 and therefore remain in the magnetization rotation layer (FGL) 2 or the rotation stabilization layer (SL) 11 so that the magnetization of the magnetization rotation layer 2 is directed to the left. Acting as a spin torque (Action 1). On the other hand, the leakage magnetic field from the main magnetic pole 5 acts to turn the magnetization of the magnetization rotation layer 2 to the right (action 2). Furthermore, the rotation stabilization layer (SL) 11 having negative perpendicular magnetic anisotropy acts so that the magnetization of the magnetization rotation layer 2 remains in the layer (operation 3). The direction of spontaneous magnetization of the magnetization rotation layer 2 is determined by the balance of action 1, action 2, and action 3, but torque is generated so as to restore the direction determined by action 2 and action 3, and the film surface Rotate at high speed. As a result, an alternating magnetic field is generated by a direct current (hereinafter referred to as a high frequency excitation current). The generated alternating magnetic field becomes maximum when the direction of the magnetization rotation layer 2 is in the film plane.

  Even when the magnetization of the main magnetic pole 5 is reversed while the current is constant, there is no change in the situation in which spin torque is applied to turn the magnetization of the magnetization rotation layer 2 in the opposite direction to the magnetization of the main magnetic pole 5. At this time, the rotation direction of the magnetization of the magnetization rotation layer 2 is opposite to the rotation direction before the magnetization direction of the main magnetic pole 5 is reversed. When the recording density increases and the width of the magnetization rotator layer 2 is narrow, the magnetic field generated from the side surface of the magnetization rotator layer 2 cannot be ignored, and the direction of the high-frequency magnetic field applied to the recording medium 7 rotates with time. (Rotating oscillating magnetic field). By using the high-frequency magnetic field generating element 201 having the configuration shown in FIG. 12, a counterclockwise oscillating magnetic field is applied to the magnetization to be reversed, and efficient microwave-assisted magnetic recording becomes possible.

  In microwave assisted magnetic recording, since the recording magnetic field from the main magnetic pole 5 and the high frequency magnetic field of the magnetization rotation layer 2 need to be superimposed on the nano region, the magnetization rotation layer 2 is exposed to the leakage magnetic field from the main magnetic pole 5. become. Of the leakage magnetic field from the main magnetic pole 5, the component perpendicular to the layer surface of the magnetization rotation layer 2 acts to increase the high-frequency magnetic field frequency from Equation (3). On the other hand, if there is a leakage magnetic field component parallel to the film surface of the magnetization rotation layer 2, the spontaneous magnetization of the magnetization rotation layer 2 is fixed in this direction, which may hinder high-frequency oscillation. By using the main magnetic pole 5 having a structure that moves away from the high-frequency magnetic field generating element 201 as it moves away from the ABS surface as shown in FIG. 12, it is possible to greatly reduce the magnetic field applied in the FGL in-plane direction. In-plane magnetization rotation is stabilized. The magnetic flux rectifying layer 8 (lip) has the effect of adjusting the direction of the leakage magnetic field from the main magnetic pole 5, increasing the magnetic field component perpendicular to the film surface of the magnetization rotation layer 2, and reducing the parallel magnetic field component as much as possible. is doing.

  For comparison, a head having a conventional structure in which the main magnetic pole 5 is not tilted was manufactured for investigation. A prototype magnetic head having a conventional structure is shown in FIG. When calculated using the three-dimensional magnetic field analysis software, it is known that a maximum magnetic field of 256 kA / m and 520 kA / m is applied in the in-plane direction of the magnetization rotation layer 2 with the structure of FIGS. . Magnetic recording was performed using a spin stand with a magnetic spacing of 5 nm and a track pitch of 20 nm, and this was reproduced by a GMR head having a shield interval of 20 nm. In the region where the main magnetic pole excitation current is weak, there was no significant difference between the two heads. However, if the main magnetic pole excitation current is increased for the purpose of improving the overwrite characteristics, the current increases when the conventional head shown in FIG. 13 is used. At the same time, the SNR was lowered, and eventually it became impossible to obtain a reproduction output. At this time, in order to confirm whether or not a microwave magnetic field was actually generated, a high frequency magnetic field detector was disposed on the opposite side of the recording medium 7 across the high frequency magnetic field generating element 201 to monitor the strength of the microwave magnetic field. However, high frequency output was not obtained. This is thought to be because high-frequency oscillation is not caused as a result of the magnetization of the magnetization rotator layer 2 being fixed in the direction of the leakage magnetic field by the leakage magnetic field of the main magnetic pole 5.

  FIG. 14 is a diagram illustrating a configuration example of a high-frequency magnetic field generator. The recording head structure shown in FIG. 12 includes the magnetic flux rectifying layer 8 and the opposing magnetic pole side magnetic flux rectifying layer 13, but the magnetic flux rectifying layer 8 and the opposing magnetic pole side magnetic flux rectifying layer 13 can be omitted as shown in FIG. It is. If the magnetic flux rectifying layer 8 is omitted, the magnetization rotation layer 2 serving as a generation source of the high-frequency magnetic field can be brought close to the main magnetic pole 5, but the leakage magnetic field component from the main magnetic pole 5 parallel to the film surface of the magnetization rotation layer 2 is increased. There is also a downside. The magnetic flux rectifying layer 8 is preferably set to an appropriate thickness. By using the structure in which the leakage magnetic field component parallel to the film surface of the magnetization rotation layer 2 of the present invention is small, the thickness of the magnetic flux rectifying layer 8 can be reduced compared to the case where it is not used.

  Further, the structure shown in FIG. 14B in which the magnetization rotation layer (FGL) 2 and the rotation stabilization layer (SL) 11 in FIG. 14A are replaced, and the non-shown in FIG. 14A and FIG. 14B. A high-frequency magnetic field generating element 201 having a structure shown in FIGS. 14C and 14D in which the magnetic spin scatterer 12 and the metal nonmagnetic spin conductive layer 15 are replaced may be used. In the case of the structure shown in FIG. 14B, the rotation stabilization layer (SL) 11 having a smaller saturation magnetization than the magnetization rotation layer (FGL) 2 is closer to the main pole 5, so that the main pole parallel to the film surface The adverse effect of the leakage magnetic field component from 5 is reduced. In addition, since the spin torque is transmitted to the magnetization rotation layer 2 from the opposed magnetic pole side magnetic flux rectifying layer 13 (or the opposed magnetic pole 6 when the opposed magnetic pole side magnetic flux rectifying layer 13 is omitted) via the nonmagnetic spin conductive layer 15, Magnetic field generation efficiency is improved. When the metal nonmagnetic spin conductive layer 15 is on the main magnetic pole side (FIG. 14C, FIG. 14D), the spin torque source is the magnetic flux rectifying layer 8, and therefore the magnetic flux rectifying layer 8 cannot be omitted. By using a very thin compound layer, metal layer, or weak magnetic layer at the interface between the main pole 5 and the magnetic flux rectifying layer 8 for the purpose of reducing exchange interaction, the high-frequency magnetic field generation efficiency is improved.

  In FIG. 14, the magnetization rotation layer 2 and the rotation stabilization layer (SL) 11 each have a single-layer structure, but may be configured by a plurality of stacked films. Alternatively, the functions of the magnetization rotation layer and the spin rectification element may be realized as the entire action of the layers arranged separately in the high-frequency magnetic field generation element 201. Furthermore, in the above description, the magnetic flux rectifying layer 8 has been described as a layer provided separately from the main magnetic pole, but may be configured as a protrusion associated with the main magnetic pole.

  As described above, the configuration of the present invention makes it possible to realize a microwave-assisted recording magnetic head capable of stable oscillation. Hereinafter, specific embodiments of the present invention will be described in detail.

  FIG. 12 shows the recording head and the recording medium cut around the recording mechanism by cutting the surface perpendicular to the recording medium surface (vertical direction in the figure) and parallel to the head running direction (track direction which is the left or right direction in the figure). FIG. The material of the main magnetic pole 5 and the counter magnetic pole 6 was a CoFe alloy having a large saturation magnetization and almost no magnetocrystalline anisotropy. In order to reduce the leakage magnetic field (FGL in-plane direction component) to the FGL 2 and stabilize high frequency oscillation, the main magnetic pole 5 is inclined to the opposite side of the high frequency magnetic field generating element 201.

  A magnetic flux rectifying layer 8, a metal nonmagnetic spin scatterer 12, an FGL (magnetization high-speed rotator) 2, a negative perpendicular magnetic anisotropy (stabilization layer SL) 11, It reaches the counter magnetic pole 6 through the magnetic spin conduction layer 15 and the counter magnetic pole side magnetic flux rectifying layer 13. The magnetic flux rectifying layer 8 to the opposing magnetic pole side magnetic flux rectifying layer 13 have a columnar structure extending in the left-right direction in the drawing, and the side of the cross section along the ABS surface is a trapezoid shorter than the opposing side. By adopting the trapezoidal shape, the high frequency magnetic field from the FGL bottom surface and the high frequency magnetic field from the FGL side surface are balanced, and a high frequency rotating magnetic field with high microwave assist inversion efficiency can be obtained. The side length w along the trapezoidal ABS surface is an important factor for determining the recording track width, and is set to 15 nm in this embodiment. In microwave assisted recording, since a recording medium having a large magnetic anisotropy that cannot be recorded unless the recording magnetic field from the main magnetic pole 5 and the high-frequency magnetic field from the FGL 2 are aligned is used, The thickness (length in the head running direction) can be set large so that a large recording magnetic field can be obtained. In this embodiment, a recording magnetic field of about 0.9 MA / m is obtained by setting the width to 80 m and the thickness to 100 nm. The magnetic flux rectifying layer 8 uses a material having the same or larger saturation magnetization as the main magnetic pole 5 and uses a three-dimensional magnetic field analysis software so that the magnetic field from the main magnetic pole 5 is as perpendicular as possible to the layer direction of the FGL 2. A thickness design of 8 was performed. The thickness of the magnetic flux rectifying layer 8 in this embodiment was 10 nm, but this value depends on the trapezoidal shape, the distance and the situation to the counter magnetic pole, the situation of the medium used, and the situation of the magnetic circuit above the drawing. To do.

  FGL2 was a CoFe alloy having a thickness of 20 nm with a large saturation magnetization and almost no magnetocrystalline anisotropy. In FGL2, the magnetization rotates at high speed in a plane along the layer, and the leakage magnetic field from the magnetic poles appearing on the ABS surface and the side surface acts as a high-frequency magnetic field. The magnetization rotation driving force of the FGL 2 is a spin torque due to the spin reflected on the opposite magnetic pole side magnetic flux rectifying layer 13 through the metal nonmagnetic spin conduction layer 15. This spin torque acts in a direction in which the magnetization component parallel to the magnetization rotation axis of the FGL 2 generated by the leakage magnetic field from the main magnetic pole 5 decreases. In order to obtain the effect of this spin torque, it is necessary to flow a high frequency excitation (DC) current from the counter magnetic pole 6 side to the main magnetic pole 5 side. When the magnetic field flows from the main magnetic pole 5, the rotation direction of the magnetization of the FGL 2 is counterclockwise when viewed from the upstream side of the high frequency excitation (DC) current, and the recording medium is reversed by the magnetic field from the main magnetic pole 5. A rotating magnetic field having the same direction as the direction of magnetization precession can be applied. When the magnetic field flows into the main magnetic pole 5, the rotation direction of the magnetization of the FGL 2 is clockwise when viewed from the upstream side of the high-frequency excitation (DC) current, and the magnetization of the recording medium that is reversed by the magnetic field to the main magnetic pole 5. A rotating magnetic field having the same direction as the differential motion direction can be applied. Therefore, the rotating high frequency magnetic field extending from FGL 2 has an effect of assisting the magnetization reversal by the main magnetic pole 5 regardless of the polarity of the main magnetic pole 5. This effect cannot be obtained with a conventional high-frequency magnetic field generator in which the direction of the spin torque does not change depending on the polarity of the main magnetic pole 5.

The spin torque action increases as the high-frequency excitation current (electron current) increases, and increases when a CoFeB layer having a high polarizability is inserted between the metal nonmagnetic spin conduction layer 15 and the adjacent layer by about 1 nm. 2 nm-Cu was used for the metal nonmagnetic spin conduction layer 15. The negative perpendicular magnetic anisotropy 11 is such that the c-axis direction of hexagonal CoIr is the left-right direction in the figure, and the magnitude of magnetic anisotropy is 6.0 × 10 ⁵ J / m ³ . Using. By making a magnetic material having negative perpendicular magnetic anisotropy adjacent to FGL2, the action of retaining the magnetization direction of FGL2 in the direction perpendicular to the rotation axis is enhanced. By this action, a strong high-frequency magnetic field can be obtained at a relatively low frequency. This effect can be similarly expected with α′-FeC, dhcpCoFe, NiAs type MnSb, and the like known as magnetic materials having negative perpendicular magnetic anisotropy. Since a CoFe alloy is used for FGL2, even if α′-FeC or dhcpCoFe is used, a large exchange interaction works as in CoIr, and the action of keeping the magnetization direction perpendicular to the rotation axis becomes strong. As the metal nonmagnetic spin scatterer 12, 3 nm-Ru was used. Even if Pd or Pt is used, the same effect is obtained. For the opposing magnetic pole side magnetic flux rectifying layer 13, a 15 nm CoFe alloy was used. The recording medium 7 is a laminated film in which a 10 nm-Ru layer is formed on a substrate 19 as a base layer 20 on a 30 nm-CoFe, and the magnetic anisotropy field is 2.4 MA / m (30 kOe) as the recording layer 16. A CoCrPt—SiOx layer having a thickness of 10 nm was used. As a result of measuring the absorption line width by ferromagnetic resonance, the damping constant α of the recording layer 16 was 0.02.

  The slider 102 mounted with the recording / reproducing unit 109 incorporating the high-frequency magnetic field generation source 201 of the present invention was attached to the suspension 106 (FIG. 10), and the recording / reproducing characteristics were examined using a spin stand. Magnetic recording was performed at a head medium relative speed of 20 m / s, a magnetic spacing of 7 nm, and a track pitch of 25 nm, and this was reproduced by a GMR head having a shield interval of 18 nm. When the signal / noise ratio at 1000 kFCI was measured by changing the high-frequency excitation current, a maximum of 13.0 dB was obtained, and it was found that recording / reproduction with a recording density exceeding 2 Tbits per square inch can be sufficiently achieved. . The high frequency frequency at this time was 35.0 GHz. In addition, when the 125 kFCI pattern was recorded on the 1000 kFCI pattern, the overwrite characteristic was 32 dB, which was further improved by increasing the main magnetic pole excitation current. On the other hand, when the conventional head (FIG. 13) in which the main magnetic pole 5 is not tilted is used, the overwrite characteristic is limited to a maximum of 25 dB, the main magnetic pole excitation current is increased and the signal / noise ratio is remarkably deteriorated so that recording becomes impossible. .

  FIG. 15A and FIG. 15B show another configuration example of the recording head that prevents the FGL portion from being influenced by the opposing magnetic pole side surface of the magnetic pole 5 as much as possible. For comparison, FIG. 15C shows a configuration diagram of the conventional head shown in FIG. FIG. 15A shows a configuration in which the height of the counter magnetic pole 6 is sufficiently higher than the height of the high-speed magnetization rotator (FGL) 2, and the difference Ht between the height of the counter magnetic pole 6 and the height of the high-frequency magnetic field generating element 201 is The distance Lf between the main magnetic pole 5 and the counter magnetic pole 6 is preferably about 0.5 to 2 times.

  FIG. 20 shows the magnetic field analysis results in the vicinity of the main pole using the three-dimensional magnetic field analysis software with the structure parameter interval Lf and the height difference Ht of FIG. 9C set as shown in Table 1. It is a thing. As in FIGS. 6 and 8, the maximum magnetic field angle is obtained by obtaining the angle from the x direction at the FGL position and obtaining the maximum value in each structure. In the normal element height direction, the position farthest from the ABS surface is the maximum.

From FIG. 20, the maximum magnetic field angle is greatly reduced when the ratio Ht / Lf is close to 0.5. If the maximum magnetic field angle exceeds 30 degrees, stable rotation of the FGL magnetization cannot be obtained from the examination of FIG. Therefore, the ratio Ht / Lf needs to take a value larger than 0.5. The graph shown together with the maximum magnetic field angle in FIG. 20 shows the ratio Ht / ratio of the z component H _z of the magnetic field at a position 5 nm down from the straight line where the joint surface of the main magnetic pole 5 and the high frequency magnetic field generating element 201 intersects the ABS surface to the recording medium side. The dependence on Lf is shown. H _z corresponds to a write magnetic field in MAMR. H _z, when the ratio Ht / Lf is small, increases slightly with increasing the ratio Ht / Lf. This is probably because the counter magnetic pole 6 acts to pull the magnetic flux from the main magnetic pole 5. When the ratio Ht / Lf becomes too large, the action of pulling the magnetic flux becomes too great, and the magnetic flux directly flows from the main magnetic pole 5 to the counter magnetic pole 6. When the ratio Ht / Lf is close to 2.0, H _z is greatly reduced, and a necessary write magnetic field cannot be obtained. The above tendency was obtained similarly even when the size of Lf was changed. However, it is preferable that Lz is smaller because _Hz is larger.

  FIG. 15B shows a configuration example for forming a bypass magnetic path. A bypass magnetic path 211 is formed from the counter magnetic pole 6 toward the main magnetic pole 5, and a leakage magnetic field from the side surface of the main magnetic pole 5 is released to the counter magnetic pole 6 through the bypass magnetic path 211. If the bypass magnetic path 211 is in contact with the main magnetic pole 5, the magnetic flux is absorbed by the counter magnetic pole 6 before reaching the tip of the main magnetic pole 5, so that the recording magnetic field from the main magnetic pole 5 becomes small. The heads of FIGS. 15A and 15B can also reduce the leakage magnetic field component from the main magnetic pole applied in the FGL magnetization rotation plane, and stable rotation of the FGL during the recording operation. As a result, a good recording pattern was formed on the recording medium, the recording density in the information recording apparatus could be increased, and at the same time the reliability could be improved, resulting in a reduction in cost.

  The relationship between the mounting position of the magnetic head with respect to the head slider and the magnetic head traveling direction will be described with reference to FIGS. There are two types of mounting modes of the magnetic head on the magnetic head slider, one is the arrangement on the trailing side shown in FIG. 16 (A) and the other is the arrangement on the leading side shown in FIG. 16 (B). . Here, the trailing side and the leading side are determined by the relative moving direction of the magnetic head slider with respect to the recording medium, and the rotation direction of the recording medium is opposite to the direction shown in FIGS. 16 (A) and 16 (B). If so, FIG. 16A shows placement on the leading side, and FIG. 16B shows placement on the trailing side. In principle, it is possible to reverse the relationship between the trailing side and the leading side if the polarity of the spindle motor is reversed and the recording medium is rotated in the opposite direction, but the rotational speed is accurately controlled. Therefore, it is unrealistic to change the polarity of the spindle motor. When the heads shown in FIGS. 15A and 15B are used, recording / reproduction with a recording density exceeding 2 Tbits per square inch is possible regardless of which arrangement shown in FIGS. 16A and 16B is used. A sufficient signal / noise ratio and overwrite characteristics were obtained.

  17 and 18 are diagrams showing a second configuration example of the recording head and the recording medium according to the present invention.

  FIGS. 17A to 17D are diagrams illustrating a second configuration example of the recording head that moves the main magnetic pole 5 away from the high-frequency magnetic field generating element 201 as the distance from the ABS surface increases. FIG. 17A is shown again so that it can be compared with FIGS. 17B to 17D with the same configuration as FIG. FIG. 17B shows another configuration example of the magnetic head of this embodiment. In the magnetic head shown in FIG. 17B, the exciting coil of the main magnetic pole 5 is wound upward rather than horizontally. In the case of the magnetic head of this configuration, since the excitation position is further away from the main magnetic pole air bearing surface than the structure of FIG. 17A, the magnetic field generated from the main magnetic pole 5 is weaker than that of FIG. Since there is a sufficient space for installing the coil 205 and the magnetic pole is not bent by bending the counter magnetic pole 6 toward the main magnetic pole 5 at the upper part in the element height direction, the structure becomes simple and an inexpensive head can be produced.

  FIG. 17C shows a configuration example of a magnetic head for microwave assist recording in which the recording head portion is disposed on the leading side and the reproducing head portion is disposed on the trailing side. In the magnetic head configured as shown in FIG. 17C, the main magnetic pole 5 is disposed at the leading end and the opposing magnetic pole 6 is disposed on the trailing side with respect to the main magnetic pole 5. In the example shown in FIG. 17C, the counter magnetic pole 6 and the regeneration sensor shield are shared, but they may be separated. The winding direction of the excitation coil 205 is an upper winding as in FIG. 17B, but may be a horizontal winding as shown in FIG. In order for the high-frequency excitation current to flow through the high-frequency magnetic field generating element 201, the main magnetic pole 5 and the counter magnetic pole 6 need to be electrically insulated.

  17A to 17D can be mounted on the magnetic head slider having any structure shown in FIGS. 16A and 16B. Further, the stacking order of the high frequency generator 201 may be any stacking order shown in FIGS.

  Although almost the same results were obtained using any of the structures shown in FIGS. 17A, 17C, and 17D, this embodiment will be described using FIG. 17C as an example. FIG. 18 is an enlarged view of a medium used with the write head unit of FIG.

  The recording medium 7 includes a substrate 19, a CoCrPt—SiOx layer having a magnetic anisotropy field of 2.4 MA / m (30 kOe) and a film thickness of 10 nm as the lower recording layer 18, and a magnetic anisotropy as the upper recording layer 17. A 6 nm- (Co / Pt) -SiOx artificial lattice layer having a magnetic field of 1.4 kA / m (17 kOe) was used. As a result of measurement of the absorption line width by ferromagnetic resonance, the damping constant α of the upper recording layer 17 and the lower recording layer 18 was 0.20 and 0.02, respectively. If there is a Pt layer or a Pd layer, α can be increased and the magnetization reversal speed can be increased. After a continuous film was formed by sputtering, a magnetic pattern having a track direction length of 15 nm and a down track direction of 6 nm was arranged by a nanoimprint technique so that the track pitch was 20.0 nm and the bit pitch was 8.0 nm. . In the gap 21 between the patterns, SiOx was embedded. Recording was performed using a spin stand at a head medium relative speed of 20 m / s, a magnetic spacing of 5 nm, and a track pitch of 20.0 nm, and this was reproduced by a GMR head having a shield interval of 12 nm. When the signal / noise ratio at 1590 kFCI was measured while changing the high-frequency excitation current, a maximum of 13.0 dB was obtained, and it was found that recording / reproduction with a recording density exceeding 4 Tbits per square inch was sufficiently achievable. . The high frequency frequency at this time was 27.0 GHz. For comparison, the recording / reproduction characteristics of the medium before patterning were measured at a head medium relative speed of 30 m / s, a magnetic spacing of 5 nm, and 27.0 GHz. The signal / noise ratio at 1250 kFCI was 13.0 dB. The increase was when the track pitch exceeded 40 nm, and it was found that recording / reproduction with a recording density exceeding 1.5 Tbits per square inch can be sufficiently achieved even with a continuous medium.

  The recording head and the recording medium shown in each configuration example of Example 1 and Example 2 according to the present invention were incorporated into a magnetic disk device, and performance evaluation was performed. 19A and 19B are schematic views showing the overall configuration of the information recording apparatus of the present embodiment. FIG. 19A is a top view, and FIG. 19B is a sectional view taken along line AA ′. The recording medium 101 is fixed to the rotary bearing 104 and is rotated by the motor 100. FIG. 19 shows an example in which three magnetic disks and six magnetic heads are mounted. However, one or more magnetic disks and one or more magnetic heads are sufficient. The recording medium 101 has a disk shape, and recording layers are formed on both sides thereof. The slider 102 moves in a substantially radial direction on the rotating recording medium surface, and has a magnetic head at the tip. The suspension 106 is supported by the rotor reactor 103 via the arm 105. The suspension 106 has a function of pressing or pulling the slider 102 against the recording medium 101 with a predetermined load. A current for driving each component of the magnetic head is supplied from the IC amplifier 113 via the wiring 108. Processing of the recording signal supplied to the recording head unit and the reproduction signal detected from the reproducing head unit is executed by the read / write channel IC 112. The control operation of the entire information processing apparatus is realized by the processor 110 executing a disk control program stored in the memory 111. Accordingly, in this embodiment, the processor 110 and the memory 111 constitute a so-called disk controller.

DESCRIPTION OF SYMBOLS 1 ... Perpendicular magnetic anisotropy body, 2 ... Magnetization high speed rotary body (FGL), 5 ... Main magnetic pole, 6 ... Opposing magnetic pole, 7 ... Recording medium, 8 ... Magnetic flux rectification layer, 11 ... Negative perpendicular magnetic anisotropy body (SL), 12 ... Metal nonmagnetic spin scatterer, 13 ... Opposite magnetic pole side magnetic flux rectifying layer, 15 ... Metal nonmagnetic spin conducting layer, 16 ... Recording layer, 17 ... Upper recording layer, 18 ... Lower recording layer, 19 ... Substrate, 20 ... underlayer, 100 ... motor, 101 ... recording medium, 102 ... slider, 103 ... rotary actuator, 104 ... rotary bearing, 105 ... arm, 106 ... suspension, 108 ... wiring, 110 ... processor, 111 ... Memory 112, channel IC 113, IC amplifier 200, recording head 201, high frequency magnetic field generator 205, coil 206, auxiliary magnetic pole 207 GMR element 208, shield film, 2 9: insulating film, 210 ... upper shield, 211 ... bypass magnetic flux path

Claims (6)

A main magnetic pole for generating a magnetization reversal magnetic field, an auxiliary magnetic pole, a counter magnetic pole, a magnetization high-speed rotating body disposed between the main magnetic pole and the counter magnetic pole, and means for supplying a direct current to the magnetization high-speed rotating body; A magnetic recording head for recording information by generating a high-frequency magnetic field from the magnetization high-speed rotating body to bring the magnetic recording medium into a magnetic resonance state and reversing magnetization by a magnetization reversal magnetic field from the main pole,
A magnetic recording head having a structure in which a component applied to a magnetization rotation surface of the high-speed magnetization rotator is reduced in a leakage magnetic field from the main magnetic pole applied to the high-speed magnetization rotator.   2. The magnetic recording head according to claim 1, wherein the height of the counter magnetic pole in the element height direction is 0.5 times the distance between the main magnetic pole and the counter magnetic pole than the height of the magnetization high-speed rotating body in the element height direction. A magnetic recording head characterized by being twice as high as   2. The magnetic recording head according to claim 1, wherein the main magnetic pole is inclined so that an upper portion in the element height direction of a connection portion with the high-speed magnetization rotator is away from the high-speed magnetization rotator. head.   2. The magnetic recording head according to claim 1, further comprising a bypass magnetic path for allowing a leakage magnetic field from the side surface of the main magnetic pole to escape to the counter magnetic pole.   4. The magnetic recording head according to claim 1, wherein the auxiliary magnetic pole also serves as the counter magnetic pole. A magnetic recording medium; a medium driving unit that drives the magnetic recording medium; a magnetic head including a magnetic recording head and a magnetic reproducing head; and a magnetic head driving unit that positions the magnetic head on the magnetic recording medium. ,
The magnetic recording apparatus according to claim 1, wherein the magnetic recording head is a magnetic head according to claim 1.

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