Thermally-assisted magnetic recording head, head gimbal assembly and magnetic recording device

A thermally-assisted magnetic recording head, includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thermally-assisted magnetic recording head that irradiates near-field light on a magnetic recording medium and records data by decreasing an anisotropic magnetic field of the magnetic recording medium and to a head gimbal assembly and a magnetic recording device to which the head is used.

2. Description of the Related Art

In the field of magnetic recording using a head and a medium, further performance improvements of thin film magnetic heads and magnetic recording media have been demanded in conjunction with a growth of high recording density of magnetic disk devices. Currently, for the thin film magnetic heads, composite type thin film magnetic heads that are configured having a configuration in which a magnetoresistive (MR) element for reading and an electromagnetic transducer element for writing are laminated are widely used.

The magnetic recording medium is a discontinuous medium in which magnetic microparticles aggregate and each of the magnetic microparticles has a single magnetic domain structure. In this magnetic recording medium, one recording bit is configured with a plurality of magnetic microparticles. Therefore, in order to increase recording density, asperities at borders between adjacent recording bits need to be reduced by decreasing the size of the magnetic microparticles. However, decreasing the size of the magnetic microparticles causes a problem in that a thermal stability of magnetizations of the magnetic microparticles is decreased along with the decrease in the volume of the magnetic microparticles.

As a countermeasure against this problem, it may be considered to increase magnetic anisotropy energy Ku of the magnetic microparticles may be considered; however, the increase in Ku causes an increase in an anisotropic magnetic field (coercive force) of the magnetic recording medium. On the other hand, an upper limit of a writing magnetic field strength for the thin film magnetic head is substantially determined by saturation magnetic flux density of a soft magnetic material configuring a magnetic core in the head. As a result, when the anisotropic magnetic field of the magnetic recording medium exceeds an acceptable value determined from the upper limit of the writing magnetic field strength, it becomes impossible to write. Currently, as a method to solve such a problem of thermal stability, a so-called thermally-assisted magnetic recording method has been proposed in which, while a magnetic recording medium formed of a magnetic material with large Ku is used, the magnetic recording medium is heated immediately before the application of the writing magnetic field so that the writing is performed with the anisotropic magnetic field being reduced.

For this thermally-assisted magnetic recording method, a method that uses a near-field light probe, a so-called plasmon generator, which is a metal piece that generates near-field light from plasmon excited by irradiated laser light, is generally known.

A magnetic recording head disposed with a conventional plasmon generator has a configuration in which a pole that generates a writing magnetic field is disposed on a trailing side with respect to a near-field light generating portion of the plasmon generator and in which a waveguide that propagates light is disposed so as to oppose the plasmon generator. This plasmon generator couples to light propagating through the waveguide in a surface plasmon mode so as to excite surface plasmon, and the surface plasmon propagates through the plasmon generator so that the near-field light is generated at the near-field light generating portion. Furthermore, under a situation where a magnetic recording medium is heated by the near-field light generated at the near-field light generating portion of the plasmon generator and the anisotropic magnetic field of the magnetic recording medium is reduced, a writing magnetic field is applied and thereby information is written.

In the magnetic recording head having such a configuration, when a distance between the near-field light generating portion that generates the near-field light in the plasmon generator and the pole that generates the writing magnetic field is large, the strength of the magnetic field applied to the magnetic recording medium with an anisotropic magnetic field reduced by the irradiation of the near-field light becomes deficient so that it becomes difficult to write information effectively. Therefore, it is considered that making the distance between the near-field light generating portion and the pole smaller by directly contacting the pole with the plasmon generator and making a thickness of the plasmon generator thinner are effectual to write information effectively. When the thickness of the plasmon generator is thinner, the peak strength of the near-field light is decreased so that a preferred thermal assist effect may not be obtained; but, on the other hand, when the thickness of the plasmon generator is thicker, the peak strength of the near-field light can be increased, but the distance between the near-field light generating portion and the pole becomes large so that it may become difficult to write information effectively.

In contrast, in the magnetic recording head having the above-described configuration, since the magnetic field continues to be applied to the magnetic recording medium that is in a cooling process after the temperature rises by the heating, the magnetic field is further applied even to the magnetic microparticles where the magnetization has not yet stabilized after the magnetic field for recording is applied. This causes the problem that sufficient signal to noise ratio (S/N ratio) cannot be obtained in the high recording density. Therefore, in order to achieve high recording density and obtain a sufficient S/N ratio, a configuration in which a magnetic field is applied prior to heating the magnetic recording medium, i.e., a configuration in which a plasmon generator in the conventional magnetic recording head is disposed on the trailing side with respect to the pole is conceivable.

An example of the above-described magnetic recording head is a magnetic recording head provided with a plasmon generator in a shape of triangular prism that protrudes in a V-shape toward a leading side (a pole side) and a pole disposed on the leading side with respect to the plasmon generator. In the magnetic recording head having this type of configuration, the plasmon generator couples to light propagating through the waveguide in the surface plasmon mode so that the surface plasmon is excited in a V-shaped protrusion portion of the plasmon generator, and the surface plasmon propagates through the V-shaped protrusion portion of the plasmon generator. Accordingly, the waveguide is disposed on the leading side of the plasmon generator, i.e., between the plasmon generator and the pole. Therefore, the distance between the near-field light generating portion in the plasmon generator and the pole becomes large, the strength of the magnetic field applied to the magnetic recording medium with an anisotropic magnetic field reduced by the irradiation of the near-field light becomes deficient, thereby it becomes difficult to write information effectively.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a thermally-assisted magnetic recording head, and a head gimbal assembly and a magnetic recording device using the thermally-assisted magnetic recording head. The thermally-assisted magnetic recording head is able to apply a magnetic field having a necessary and sufficient strength for magnetization reversal to a portion on a magnetic recording medium that is heated by irradiating near-field light even when a plasmon generator for generating the near-field light and a pole for generating a write magnetic field are separated.

In order to realize the object, a thermally-assisted magnetic recording head includes: a pole that generates a writing magnetic field from an end surface that forms a portion of an air bearing surface opposing a magnetic recording medium; a waveguide through which light for exciting a surface plasmon propagates; a plasmon generator that couples to the light in a surface plasmon mode and generates near-field light from a near-field light generating portion on a near-field light generating end surface that forms the portion of the air bearing surface; and magnetic field focusing parts that are able to focus the writing magnetic field generated from the pole and that are disposed on both sides of the pole in a track width direction from a perspective of the air bearing surface side.

In the invention above (1st invention), it is preferred that respective gaps between the magnetic field focusing parts and the waveguide in the track width direction are 375 nm or more from the perspective of the air bearing surface side (2nd invention), further it is preferred that respective gaps between the magnetic field focusing parts and the waveguide in the track width direction are in a range of 1-3 μm from the perspective of the air bearing surface side (3rd invention).

In the invention above (1st invention), the plasmon generator may be disposed on a trailing side with respect to the pole (4th invention), or the plasmon generator is disposed on a leading side with respect to the pole (5th invention).

In the invention above (4th invention), it is preferred that, from a perspective of the air bearing surface side such that the trailing side of the thermally-assisted magnetic recording head is positioned above, upper ends of the magnetic field focusing parts are positioned above an upper end of the pole (6th invention), it is also preferred that, from a perspective of the air bearing surface side such that the trailing side of the thermally-assisted magnetic recording head is positioned above, the upper ends of the magnetic field focusing parts are positioned on approximately the same height as the near-field light generating portion (7th invention).

In the invention above (4th invention), it is preferred that, the waveguide may be positioned at a location recessed from the pole along a direction perpendicular to the air bearing surface from a perspective of the air bearing surface side (8th invention), or the waveguide may be positioned between the plasmon generator and the pole.

Further, the invention provides a head gimbal assembly including the thermally-assisted magnetic recording head according to the invention above (1st invention), a suspension supporting the thermally-assisted magnetic recording head (10th invention).

Furthermore, the invention provides a magnetic recording device including the thermally-assisted magnetic recording head according to the invention above (1st invention), a positioning device that supports the thermally-assisted magnetic recording head and positions the thermally-assisted magnetic head with respect to the magnetic recording medium (11th invention).

With the present invention, it is possible to provide a thermally-assisted magnetic recording head, and a head gimbal assembly and a magnetic recording device using the thermally-assisted magnetic recording head. The thermally-assisted magnetic recording head is able to apply a magnetic field having a necessary and sufficient strength for magnetization reversal to a portion on a magnetic recording medium that is heated by irradiating near-field light even when a plasmon generator for generating the near-field light and a pole for generating a write magnetic field are separated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to explaining embodiments of the present invention, terminologies used in the present specification are defined. In a lamination structure or an element structure formed on an element formation surface of a slider substrate of a magnetic recording head according to embodiments of the present invention, from a perspective of a layer or element to be a standard, a substrate side is referred to as “lower (below),” and an opposite side is referred to as “upper (above).” In addition, in the magnetic recording head according to embodiments of the present invention, “X, Y and Z axis directions” are defined in some of the drawings as necessary. Here, the Z axis direction corresponds to the above-described “up and down directions”, +Z side corresponds to a trailing side, and −Z side corresponds to a leading side. Moreover, the Y axis direction is a track width direction, and the X axis direction is a height direction

A thermally-assisted magnetic recording head according to one embodiment of the present invention is explained with reference to the drawings.

FIG. 1is a perspective view schematically illustrating a magnetic recording device of the present embodiment.FIG. 2is a perspective view schematically illustrating a head gimbal assembly (HGA) of the present embodiment.FIG. 3is a perspective view illustrating a thermally-assisted magnetic recording head according to the present embodiment.

As illustrated inFIG. 1, a magnetic disk device as a magnetic recording device according to the present embodiment includes a plurality of magnetic disks301, an assembly carriage device310, head gimbal assemblies (HGA)312and a control circuit330. The magnetic disks301rotate around a rotational shaft of a spindle motor302. The assembly carriage device310is provided with a plurality of drive arms311. The HGAs312each is attached to a tip portion of each of the drive arms311and has the thermally-assisted magnetic recording head1, which is a thin film magnetic head, according to the present embodiment. The control circuit330controls writing and reading operations of the thermally-assisted magnetic recording head1according to the present embodiment and controls a light emission operation of a laser diode, which is a light source that generates laser light for after-mentioned thermally-assisted magnetic recording.

In the present embodiment, the magnetic disks301are for perpendicular magnetic recording and each has a configuration in which a soft magnetic under layer, an intermediate layer and a magnetic recording layer (perpendicularly magnetized layer) are sequentially laminated on a disk substrate.

The assembly carriage device310is a device for positioning the thermally-assisted magnetic recording head1on a track, which is formed on the magnetic disk301and on which recording bits are arrayed. In the assembly carriage device310, the drive arms311are stacked in a direction along a pivot bearing shaft313and are angularly swingable by a voice coil motor (VCM)314centering around the pivot bearing shaft313.

The configuration of the magnetic disk device of the present embodiment is not limited to the above-described configuration but may include only a singular of the magnetic disk301, the drive arm311, the HGA312and the thermally-assisted magnetic recording head1.

In the HGA312illustrated inFIG. 2, a suspension320includes a load beam321, a flexure322that is firmly attached to the load beam321and has elasticity, and a base plate323disposed at a base of the load beam321. In addition, a wiring member324formed from a lead conductor and connection pads electrically connected to both sides of the lead conductor are disposed on the flexure322. The thermally-assisted magnetic recording head1according to the present embodiment is firmly attached to the flexure322at a tip portion of the suspension320so as to oppose a surface of the respective magnetic disk301with a predetermined space (flying height). Further, an end of the wiring member324is electrically connected to a terminal electrode of the thermally-assisted magnetic recording head1according to the present embodiment.

As illustrated inFIG. 3, the thermally-assisted magnetic recording head1according to the present embodiment includes a slider10and a light source unit50. The slider10, formed of ALTIC (Al2O3—TiC) or the like, is provided with a slider substrate11having an air bearing surface (ABS)11aand an element formation surface11b, and a head part12. The ABS11aas a medium opposing surface is processed to obtain an appropriate flying height, the element formation surface11bis perpendicular to the ABS11a, and the head part12is formed on the element formation surface11b.

Furthermore, the light source unit50is formed of ALTIC (Al2O3—TiC) or the like, and is provided with a unit substrate51having a joining surface51a, and a laser diode60as a light source disposed on a light source installation surface51bthat is perpendicular to the joining surface51a.

Here, the slider10and the light source unit50are joined with each other in a manner of contacting a back surface11cof the slider substrate11with the joining surface51aof the unit substrate51. The back surface11cof the slider substrate11means an end surface of the slider substrate11on the opposite side from the ABS11a. Note, the thermally-assisted magnetic recording head1according to the present embodiment may have a configuration in which the laser diode60is directly attached to the slider10without using the light source unit50.

The head part12formed on the element formation surface11bof the slider substrate11includes a head element20, a waveguide23, a plasmon generator24, magnetic field focusing parts25, a protective layer31, a pair of first terminate electrodes26aand a pair of second terminate electrodes26b. The head element20has an MR element21for reading out data from the magnetic disk301and an electromagnetic transducer element22for writing data on the magnetic disk301. The waveguide23is disposed for guiding the laser light from the laser diode60disposed on the light source unit50to an air bearing surface side. The plasmon generator24forms a near-field light generating optical system with the waveguide23. The magnetic field focusing parts25(seeFIGS. 5 and 6) are disposed for focusing a writing magnetic field generated from the electromagnetic transducer element22to a predetermined portion. The protective layer31is formed on the element formation surface11bso as to cover the MR element21, the electromagnetic transducer element22, the waveguide23, the plasmon generator24and the magnetic field focusing parts25(seeFIGS. 5 and 6). The pair of first terminal electrodes26ais exposed on an upper surface of the protective layer31and is electrically connected to the MR element21. The pair of second terminal electrodes26bis exposed on the upper surface of the protective layer31and is electrically connected to the electromagnetic transducer element22. The first and second terminal electrodes26aand26bare electrically connected to the connection pad of the wiring member324disposed to the flexure322(seeFIG. 2).

Ends of the MR element21, the electromagnetic transducer element22, the plasmon generator24and the magnetic field focusing parts25(seeFIGS. 5 and 6) reach a head part end surface12a, which is the air bearing surface of the head part12. Here, the head part end surface12aand the ABS11aform the entire medium opposing surface of the thermally-assisted magnetic recording head1according to the present embodiment.

During the actual writing and reading, the thermally-assisted magnetic recording head1hydro-dynamically flies on the surface of the rotating magnetic disk301with a predetermined flying height. At this time, the end surfaces of the MR element21and the electromagnetic transducer element22oppose the surface of the magnetic recording layer of the magnetic disk301with an appropriate magnetic spacing. In this state, the MR element21performs the reading by sensing a data signal magnetic field from the magnetic recording layer, and the electromagnetic transducer element22performs the writing by applying a writing magnetic field to the magnetic recording layer.

At the time of the writing, the laser light that propagates from the laser diode60of the light source unit50through the waveguide23is coupled with the plasmon generator24in a surface plasmon mode and excites a surface plasmon at the plasmon generator24. This surface plasmon propagates along the later-discussed propagation edge of the plasmon generator24towards the head part end surface12aso that the near-field light is generated at the end part of the plasmon generator24on the head part end surface12aside. This near-field light reaches the surface of the magnetic disk301so that a portion of the magnetic recording layer of the magnetic disk301is heated. As a result, anisotropic magnetic field (coercive force) at that portion decreases to a value at which the writing becomes possible. It becomes able to perform the thermally-assisted magnetic recording by applying a writing magnetic field to the portion where the anisotropic magnetic field has decreased.

FIG. 4is a cross-sectional view cut along the A-A line (XZ plane) inFIG. 3that schematically illustrates a configuration of the thermally-assisted magnetic recording head1according to the present embodiment.

As illustrated inFIG. 4, the MR element21has a lower shield layer21aformed on a first insulating layer32aon an element forming surface11bof the slider substrate11, an MR multilayer body21bformed on the lower shield layer21a, and an upper shield layer21cformed on the MR multilayer body21b. A second insulating layer32bis disposed between the lower shield layer21aand the upper shield layer21cin the periphery of the MR multilayer body21b. The lower shield layer21aand the upper shield layer21cprevent the MR multilayer body21bfrom being affected by external magnetic fields which are noise.

The lower shield layer21band the upper shield layer21care magnetic layers with a thickness of approximately 0.5-3 μm formed by, for example, a frame plating method, a spattering method or the like, and are formed by a soft magnetic material, for example, NiFe (permalloy), FeSiAl (sendust), CoFeNi, CoFe, FeN, FeZrN, CoZrTaCr or the like, or a multilayer film formed by these materials.

The MR multilayer body21bis a magnetically sensitive portion that senses the signal magnetic field using the MR effect and may be any of a current-in-plane giant magnetoresistive (CIP-GMR) multilayer body that uses a current-in-plane giant magnetoresistive effect, a current-perpendicular-to-plane giant magnetoresistive (CPP-GMR) multilayer body that uses a current-perpendicular-to-plane giant magnetoresistive effect, and a tunnel-magnetoresistive (TMR) multilayer body that uses a tunnel magnetoresistive effect. When the MR multilayer body21bis a CPP-GMR multilayer body or a TMR multilayer body, the lower shield layer21aand the upper shield layer21cfunction as electrodes also. On the other hand, when the MR multilayer body21bis a CIP-GMR multilayer, insulating layers are disposed respectively between the MR multilayer body21band the lower shield layer21aand between the MR multilayer body21band the upper shield layer21c. Moreover, an MR lead layer that is electrically connected to the MR multilayer body21bis disposed.

When the MR multilayer body21bis a TMR multilayer, the MR multilayer body21bhas a structure in which the following are sequentially laminated: an antiferromagnetic layer formed of, for example, IrMn, PtMn, NiMn, RuRhMn or the like having a thickness of approximately 5-15 nm; a magnetization pinned layer that has a structure in which two ferromagnetic layers formed of CoFe or the like sandwich a nonmagnetic metal layer formed of Ru or the like and of which a magnetization direction is pinned by the antiferromagnetic layer; a tunnel barrier layer formed of a nonmagnetic dielectric material in which a metal film formed of Al, AlCu or the like having a thickness of approximately 0.5-1 nm is oxidized by oxygen introduced into a vacuum device or by natural oxidation; and a magnetization free layer that is configured with a double layer film formed by a layer of CoFe or the like having a thickness of approximately 1 nm and a layer of NiFe or the like having a thickness of approximately 3-4 nm, which are ferromagnetic materials, and that achieves tunnel exchange coupling with the magnetization pinned layer with the tunnel barrier layer therebetween.

The head part12in the present embodiment includes a third insulating layer32cdisposed on the upper shield layer21c, an interelement shield layer33disposed on the third insulating layer32c, and a fourth insulating layer32ddisposed on the interelement shield layer33. The interelement shield layer33may be formed from a soft magnetic material, and has a function that shields the MR element21from the magnetic field generated at the electromagnetic transducer element22disposed on the fourth insulating layer32d. The third insulating layer32cand the interelement shield layer33may be omitted.

The electromagnetic transducer element22is for perpendicular magnetic recording, and includes a lower yoke layer22adisposed on the fourth insulating layer32d, a first linkage layer22bdisposed on the lower yoke layer22ain a position away from the head part end surface12ain the X axis direction, an upper yoke layer22cthat is disposed on the first linkage layer22band that does not reach the head part end surface12a, a writing coil22dwith a spiral structure in which the writing coil22dis wound around the first linkage layer22bso as to pass through at least between the lower yoke layer22aand the upper yoke layer22ceach turn, a second linkage layer22ethat is disposed on the upper yoke layer22cand that reaches the head part end surface12aso as to form a portion of the head part end surface12a, and a pole22fthat is disposed on the second linkage layer22eand that reaches the head part end surface12aso as to form a portion of the head part end surface12a.

The head part12in the present embodiment includes a fifth insulating layer32edisposed on the lower yoke layer22a, sixth insulating layers32fdisposed between winding lines of the writing coil22dand in its periphery as well as in the area around the linkage layer22b, a seventh insulating layer32gdisposed on the writing coil22dand the sixth insulating layer32f, a eighth insulating layer32hdisposed in the area around the upper yoke layer22c, and a ninth insulating layer32idisposed in the area around the second linkage layer22eon the upper yoke layer22c, and a 10thinsulating layer32jdisposed in an area around a plasmon generator24on a waveguide23. Note, in respective areas around the lower yoke layer22aand the upper yoke layer22c, the insulating layers are disposed.

In the head part12in the present embodiment, the lower yoke layer22a, the first linkage layer22b, the upper yoke layer22cand the pole22fform a magnetic guide path that allows the magnetic flux corresponding to the magnetic field generated by the writing coil22dto pass through, and guides the magnetic flux to the magnetic recording layer (perpendicular magnetization layer) of the magnetic disk301. The furthest trailing side of the end surface220of the pole22fthat forms a portion of the head part end surface12ais the point that generates the writing magnetic field.

The pole22fis preferably formed from a soft magnetic material having a higher saturation magnetic flux density than the upper yoke layer22c, and is formed from a soft magnetic material such as, for example, FeNi, FeCo, FeCoNi, FeN, FeZrN or the like, which are iron-based alloy materials having Fe as a main component. The thickness of the pole22fin the Z axis direction can be set from 0.1 to 0.8 μm.

Furthermore, the width of the pole22fin the Y axis direction is preferably from 0.2 to 0.4 μm. When the width of the pole22fin the Y axis direction is within the aforementioned range, a magnetic field having a writable intensity can be appropriately applied to the heating spot of the magnetic disk301that is heated by the near-field light irradiated from the near-field light generating portion of the plasmon generator24together with the function of the magnetic field focusing parts25(seeFIGS. 5 and 6), which are described below.

The end surface of the upper yoke layer22con the head part end surface12aside does not extend to the head part end surface12a, and is positioned at a location recessed from the head part end surface12aby a predetermined distance toward the head part back end surface12bside in the X axis direction. Thereby, magnetic flux can be focused at the pole22f, and the intensity of the magnetic field generated from the pole22fcan be strengthened.

The writing coil22dis formed from a conductive material such as Cu (copper) or the like. Note, the writing coil22dis a single layer in the present embodiment; however, the writing coil22dmay be two or more layers or may be a helical coil arranged such that the upper yoke layer22cis interposed therebetween. Furthermore, the number of windings of the writing coil22dis not particularly limited, and can be set from 2 to 7 turns, for example.

The lower yoke layer22ais formed on a forth insulating layer32dformed of an insulation material such as Al2O3(alumina), and functions as a waveguide that guides a magnetic flux that returns from a soft magnetic under layer disposed under the magnetic recording layer (perpendicular magnetization layer) of the magnetic disk301. The lower yoke layer22ais formed by a soft magnetic material and has a thickness of approximately 0.5-5 μm, for example.

The waveguide23is disposed at a recessed position from the pole22fin the X axis direction (height direction) from a perspective of the ABS11a(the head part end surface12a). The plasmon generator24is disposed above the pole22f(on the trailing side). The waveguide23and the plasmon generator24form an optical system for generating near-field light in the head part12

The waveguide23is extended in parallel with the element formation surface11bfrom a rear end surface23athat forms a portion of a head part rear end surface12btoward a rear end surface of the pole22fwith a predetermined gap between the rear end surface of the pole22fand an end surface23bso as not to contact the pole22f. In addition, the upper surface (a portion of side surfaces) of the waveguide23and a portion of a propagation edge241of the plasmon generator24oppose each other with a predetermined gap. A part that is sandwiched between those parts forms a buffer portion40that has a lower refractive index than the refractive index of the waveguide23.

The buffer portion40functions to couple the laser light that propagates through the waveguide23to the plasmon generator24in the surface plasmon mode. Note, the buffer portion40may be a part of a tenth insulating layer32jor may be another layer disposed separately from the tenth insulating layer32j.

On both sides of the pole22fin the track width direction (the Y axis direction) from a perspective of the head part end surface12aside, the magnetic field focusing parts25(seeFIGS. 5 and 6) are disposed. The magnetic field focusing parts25function to focus a writing magnetic field generated from the pole22fto a heating point heated by a near-field light irradiated from the near-field light generating portion NFP (seeFIG. 6) of the plasmon generator24. The specific structures of the pole22f, the waveguide23, the plasmon generator24and the magnetic field focusing parts25are described later.

As illustrated inFIG. 4, the light source unit50includes the unit substrate51, the laser diode60disposed on the light source installation surface51bof the unit substrate51, a first drive terminal electrode61electrically connected to an electrode that forms a lower surface60aof the laser diode60, and a second drive terminal electrode62electrically connected to an electrode that forms an upper surface60bof the laser diode60. The first and second drive terminal electrodes61and62are electrically connected to the connection pads of the wiring member324(seeFIG. 2) disposed at the flexure322(seeFIG. 2). When a predetermined voltage is applied to the laser diode60from the first and second drive terminal electrodes61and62, laser light is radiated from an emission center positioned on an emission surface60cof the laser diode60. In the head structure illustrated inFIG. 4, an oscillation direction of the electric field of laser light that the laser diode60generates is preferably perpendicular (Z axis direction) to a lamination layer surface of an active layer60d. That is, it is preferable that the laser light that the laser diode60generates is a TM-mode polarized light. As a result, the laser light that propagates through the waveguide23becomes able to be coupled properly with the plasmon generator24in the surface plasmon mode through the buffer portion40.

For the laser diode60, InP-type, GaAs-type, and GaN-type diodes etc. may be used that are generally used for communication, optical disk storage, material analysis or the like. As long as the wavelength λLfor the radiated laser light is in a range of 375 nm-1.7 μm, for example, the wavelength is practical.

Specifically, an InGaAsP/InP quaternary mixed crystal type laser diode, of which the available wavelength region is considered to be 1.2-1.67 μm, for example, is also possible to be used. The laser diode60has a multilayer structure that includes an upper electrode60e, the active layer60dand a lower electrode60f. Reflection layers for exciting the oscillation by total reflection are formed on the front and back of cleavage surfaces of this multilayer structure. In a reflection layer60g, an aperture is disposed at a position of the active layer60dthat includes the emission center60h. A thickness TLAof the laser diode60can be set to be approximately 60-200 μm, for example.

Also, a power source in the magnetic disk device can be used for driving the laser diode60. In fact, magnetic disk devices normally have a power source of approximately 5V, for example, which is a sufficient voltage for operating the laser oscillation. In addition, power consumption of the laser diode60is approximately several tens of mW, for example, which can be sufficiently covered by the power source in the magnetic disk device. The power source applies a predetermined voltage to the first drive terminal electrode61that is electrically connected to the lower electrode60fand the second drive terminal electrode62that is electrically connected to the upper electrode60e, and the laser diode60is oscillated, so that the laser light is radiated from the aperture including the emission center60hin the reflection layer60g. The laser diode60and the first and second drive terminal electrodes61and62are not limited to the above-discussed embodiment. For example, the electrodes may be positioned in a vertically reversed manner in the laser diode60, and the upper electrode60emay be joined to the light source installation surface51bof the unit substrate51. Furthermore, it is possible to dispose a laser diode on the element formation surface11bof the thermally-assisted magnetic recording head1in order to optically connect the laser diode to the waveguide23. Moreover, when the laser diode60is not disposed in the thermally-assisted magnetic recording head1, the emission center of a laser diode disposed in the magnetic disk device and the rear end surface23aof the waveguide23may be connected with each other by an optical fiber or the like, for example.

The sizes of the slider10and the light source unit50may be arbitrary. For example, the slider10may be also a so-called femto slider having a width of 700 μm in the track width direction (Y axis direction), a length of 850 μm (in Z axis direction) and a thickness of 230 μm (in X axis direction). In this case, the size of the light source unit50may be one size smaller than the size of the slider and may have a width of 425 μm in the track width direction, a length of 300 μm and a thickness of 300 μm.

By connecting the above-described light source unit50and slider10, the thermally-assisted magnetic recording head1is configured. When being connected, the joining surface51aof the unit substrate51and the back surface11cof the slider substrate11are contacted each other. At this time, the position of the unit substrate51and the slider substrate11are determined such that the laser light generated from the laser diode60enters into the rear end surface23aof the waveguide23that is on a side opposite to the ABS11a.

Next, a specific configuration of the waveguide23, the plasmon generator24, the pole22fand the magnetic field focusing parts25of the thermally-assisted magnetic recording head1according to the present embodiment is described.FIG. 5is a perspective view schematically illustrating a configuration of the waveguide23, the plasmon generator24, the pole22fand the magnetic field focusing parts25of the thermally-assisted magnetic recording head1according to the present embodiment. InFIG. 5, the head part end surface12aincluding a portion from which the writing magnetic field and the near-field light are radiated to the magnetic recording medium is positioned on the left side.

As illustrated inFIG. 5, the thermally-assisted magnetic recording head1according to the present embodiment includes the waveguide23for propagating a laser light63for generating a near-field light, and the plasmon generator24having the propagation edge241that propagates the surface plasmon excited by the laser light (waveguide light)63.

The plasmon generator24includes the near-field light generating end surface24athat extends to the head part end surface12a(seeFIG. 6). In addition, the portion, sandwiched by a portion of the side surface23cof the waveguide23and a portion of lower surfaces (side surfaces)24band24cof the plasmon generator24including the propagation edge241, forms the buffer portion40. That is, the propagation edge241is covered by the buffer portion40. This buffer portion40functions to couple the laser light (waveguide light)63to the plasmon generator24in the surface plasmon mode. In addition, the propagation edge241functions to propagate the surface plasmon excited by the laser light (waveguide light)63to the near-field light generating end surface24a.

Note, in the present embodiment, side surfaces of the waveguide23refer end surfaces23c-23fout of end surfaces surrounding the waveguide23, excluding the end surface23band the rear end surface23aopposite to the end surface23b. The side surfaces of the waveguide23are the surfaces on which the laser light (waveguide light)63propagating in the waveguide23, which corresponds to a core, may totally reflect. In the present embodiment, the side surface23cof the waveguide23having a portion of which contacts the buffer portion40is an upper surface of the waveguide23.

More specifically, the laser light (waveguide light)63that has propagated to the vicinity of the buffer portion40induces the surface plasmon mode at the propagation edge241of the plasmon generator24by being coupled to the optical configuration of the plasmon generator24formed by the waveguide23having a predetermined refractive index nWG, the buffer portion40having a predetermined refractive index nBF, and the plasmon generator24made of a conductive material such as metal or the like. That is, the laser light (waveguide light)63is coupled to the plasmon generator24in the surface plasmon mode. This induction of the surface plasmon mode becomes possible to be achieved by setting the refractive index nBFof the buffer portion40to be smaller than the refractive index nWGof the waveguide23(nBF<nWG). Actually, evanescent light is excited in the buffer portion40based on the optical interfacial condition between the waveguide23, which is the core, and the buffer portion40. Then, the surface plasmon mode is induced as the evanescent light and a fluctuation of charges excited at the surface (propagation edge241) of the plasmon generator24are coupled each other, and the surface plasmon70is excited (seeFIG. 11). Here, the propagation edge241is located closest to the waveguide23on the lower surfaces (side surfaces)24band24cof the plasmon generator24and is angular shaped so that the electric field is more likely to be focused. As a result, the surface plasmon70(seeFIG. 11) is more likely to be excited with this configuration.

The gap (the thickness of the buffer portion40immediately below the propagation edge241) between the upper surface of the waveguide23(surface opposing the plasmon generator24) and the propagation edge241of the plasmon generator24is not particularly limited as long as the surface plasmon70is excited on the propagation edge241.

Respective gaps G between side surfaces23dand23f(side surfaces23dand23fof portions sandwiched by two magnetic field focusing parts25in the track width direction (Y axis direction)) positioned on the pole22fside in the side surfaces23dand23fof the waveguide23and the magnetic field focusing parts25, which will be described later, are preferably more than the wavelength λLof the laser light irradiated from the laser diode60and entered into the waveguide23. Specifically, the respective gaps G can be arbitrarily set depending on the wavelength λLof the laser light irradiated from the laser diode60. The respective gaps G are preferably 375 nm or more and are more preferably between 1 μm and 3 μm. As will be described later, because the magnetic field focusing parts25are formed of a soft magnetic material, when the respective gaps G are less than the wavelength of the laser light λL, the light propagating through the waveguide23is absorbed by the magnetic field focusing parts25and thereby the light peak intensity of the near-field light generated from the near-field light generating portion NFP is decreased. As a result, it may not be able to obtain the preferred thermally-assisted effect.

The plasmon generator24has a substantially triangular prism shape extending in the X axis direction. As is made clear inFIG. 5, a portion of the propagation edge241opposes the waveguide23with the buffer portion40therebetween, and extends to the near-field light generating end surface24a. Thereby, the propagation edge241can realize a function of propagating the surface plasmon excited by the laser light (waveguide light) that propagates through the waveguide23to the near-field light generating end surface24a. In other words, the plasmon generator24is coupled with the waveguide light in the surface plasmon mode, and propagates the surface plasmon on the propagation edge241. As a result, near-field light is generated from the near-field light generating portion NFP on the near-field light generating end surface24a.

The plasmon generator24is preferably formed of a conductive material such as a metal (e.g., Pd, Pt, Rh, Ir, Ru, Au, Ag, Cu or Al) or an alloy made of at least two types of these metals.

The waveguide23is disposed in a position recessed more than the pole22fin the X axis direction (height direction) with a predetermined gap with the rear end surface of the pole22f. Then, between the rear end surface of the pole22fand the end surface23bof the waveguide23, a portion of the tenth insulating layer32jmay be disposed or another insulating layer other than the tenth insulating layer32jmay be also disposed. With such a configuration, the waveguide23and the pole22fcan be positionally separated from each other. As a result, a case can be avoided, in which the amount of light to be converted to the near-field light decreases due to a portion of the laser light (waveguide light)63being absorbed by the pole22fformed by a metal.

Regarding the shape of the waveguide23, the width in the track width direction (Y axis direction) may be constant. However, the width of a portion of the waveguide23in the vicinity of rear end surface of the pole22fmay be narrower in the track width direction (Y axis direction) as illustrated inFIG. 5. The width WWG1in the track width direction (Y axis direction) at a portion on the rear end surface23aside that is on the opposite side to the end surface23bof the waveguide23can be approximately 0.5-20 μm, for example. The width WWG2in the track width direction (Y axis direction) at the portion on the end surface23bside can be approximately 0.3-10 μm, for example. The thickness TWGat the portion on the rear end surface23aside (in the Z axis direction) can be approximately 0.1-4 μm, for example. The height (length) HWG(in the X axis direction) can be approximately 10-300 μm, for example.

The upper surface23cand both end surfaces23dand23fin the track width direction (Y axis direction) of the waveguide23, with excerption of the portion contacting the buffer portion40, contact the tenth insulating layer32j(seeFIG. 4). The lower surface23eof the waveguide23contacts the ninth insulating layer32i(seeFIG. 4). Here, the waveguide23is configured from a material having a refractive index nWGthat is higher than the refractive index nISof the material forming the ninth insulating layer32iand the tenth insulating layer32j. For example, when the wavelength λLof the laser light is 600 nm, and when the ninth insulating layer32iand the tenth insulating layer32jare formed of SiO2(silicon dioxide; n=1.46), the waveguide23may be formed of Al2O3(alumina; n=1.63). In addition, when the ninth insulating layer32iand the tenth insulating layer32jare formed of Al2O3(n=1.63), the waveguide23may be formed of SiOxNy(n=1.7-1.85), Ta2O5(n=2.16), Nb2O5(n=2.33), TiO (n=2.3-2.55) or TiO2(n=2.3-2.55). When the waveguide23is formed of such materials, propagation loss of the laser light (waveguide light)63can be maintained low due to excellent optical characteristics that the materials themselves have. Further, while the waveguide23functions as a core, the ninth insulating layer32iand the tenth insulating layer32jfunction as a cladding, so that the condition for total reflection off the entire side surfaces is established. As a result, more laser light (waveguide light)63reaches the position of the buffer portion40, and the propagation efficiency of the waveguide23increases.

Further, the waveguide23may have a multilayer structure of dielectric materials in which layers in the upper position have the higher refractive index n. For example, such a multilayer structure may be established by sequentially laminating dielectric materials of which composition ratio of X and Y is appropriately varied when the waveguide23is formed of SiOxNy. The number of laminated layers may be 8-12 layers, for example. As a result, when the laser light (waveguide light)63is linearly polarized light in the Z axis direction, it becomes possible to propagate the laser light (waveguide light)63farther toward the buffer portion40side in the Z axis direction. At that time, by selecting the composition of each layer in the multilayer structure, the layer thickness and the number of layers, the preferred propagation position for the laser light (waveguide light)63in the Z axis direction can be obtained.

The buffer portion40is formed of a dielectric material having a refractive index nBFthat is lower than the refractive index nWGof the waveguide23. For example, when the wavelength λLof the laser light is 600 nm and the waveguide23is formed by Al2O3(alumina; n=1.63), the buffer portion40may be formed of SiO2(silicon dioxide; n=1.46). In addition, when the waveguide23is formed of Ta2O5(n=2.16), the buffer portion40may be formed by SiO2(n=1.46) or Al2O3(n=1.63). In these cases, the buffer portion40may be configured as a part of the tenth insulating layer32j(seeFIG. 4) formed of SiO2(n=1.46) or Al2O3(n=1.63) and functioning as a cladding. Moreover, the length LBF(in the X axis direction) of the buffer portion40, which is sandwiched by the side surface23cof the waveguide23and the propagation edge241, is preferably 0.5-5 μm and is preferably larger than the wavelength λLof the laser light (waveguide light)63. In this case, the buffer portion40has a significantly larger region compared to the so-called “focal region” formed when the laser light is focused at the buffer portion40and the plasmon generator24for being coupled in the surface plasmon mode. Therefore, coupling in the extremely stable surface plasmon mode becomes possible. The thickness TBF(in the Z axis direction) of the buffer portion40is preferably 10-200 nm. These length LBFand thickness TBFof the buffer portion40are important parameters for obtaining appropriate excitation and propagation of the surface plasmon.

FIG. 6is a plan view illustrating a shape on or near the head part end surface12aof the waveguide23, the plasmon generator24, the pole22fand the magnetic field focusing parts25of a thermally-assisted magnetic recording head1according to the present embodiment

As illustrated inFIG. 6, the pole22fextends to the head part end surface12a. The end surface220on the head part end surface12aof the pole22fhas a substantially quadrilateral shape such as a rectangle, a square, a trapezoid or the like, for example.

On the head part end surface12a, the plasmon generator24has a nearly triangular shape on the leading side of which the propagation edge241is positioned. The near-field light generating portion NFP of the plasmon generator24on the head part end surface12acan function as a light emission point of near-field light because of being positionally separated from the pole22f. Note, the plasmon generator24has the nearly triangular shape, on the leading side of which the propagation edge241is positioned, on the head part end surface12ain the present embodiment. However, as long as near-field light is generated, the shape is not limited to the nearly triangular shape and may be any other shape.

From a perspective of the ABS11a(head part end surface12a) side, the magnetic field focusing parts25are installed on the lower yoke layer22aso as to sandwich the pole22ffrom its both sides in the Y axis direction and each includes a end surface25athat forms a portion of the head part end surface12a.

The magnetic field focusing parts25are formed of an alloy materials including Ni, Fe or Co such as NiFe (permalloy), FeSiAl (sendust), NiFeCo, CoFe, FeN, FeZrN, CoZrTaCr or the like, or soft magnetic materials such as a multilayer film formed of these materials.

From a perspective of the ABS11a(head part end surface12a) side where the trailing side is located in the upper position, end surfaces (upper end surfaces)25bof the magnetic field focusing parts25on the trailing side are preferably positioned upper (on trailing side) than an end surface (upper end surface)221of the pole22fon the trailing side. As illustrated inFIG. 6, the end surfaces (upper end surfaces)25bare more preferably positioned on approximately the same height as the near-field light generating portion NFP of the plasmon generator24. As is made clear in examples, which is described below, when the upper end surfaces25bof the magnetic field focusing parts25are positioned upper than the upper end surface221of the pole22f, a magnetic field intensity of a writing magnetic field, which is at a portion on the magnetic recording medium heated by near-field light generated from the near-field light generating portion NFP, from the pole22fcan be increased. When the upper end surfaces25bof the magnetic field focusing parts25are positioned on approximately the same height as the near-field light generating portion NFP, the magnetic field intensity can be further increased.

In the present embodiment, because the width of the pole22fin the track width direction (Y axis direction) is the same as the width of the end surface23bof the waveguide23in the track width direction (Y axis direction), respective gaps G′ between the magnetic field focusing part25and a side surface222of the pole22fand between the magnetic field focusing part25and a side surface223of the pole22fare preferably 375 nm or more, and are more preferably 1-3 μm. When the respective gaps G′ are in the above-described range, the magnetic field intensity can be increased.

Note, the widths WPLof the magnetic field focusing parts25in the Y axis direction are approximately 0.2-15.0 μm, and the lengths LPL(seeFIG. 5) in the X axis direction are approximately 0.5-10.0 μm.

In the above-described embodiment, the waveguide23is disposed in the position recessed more than the pole22fin the X axis direction (height direction) from a perspective of the ABS11aside; but, the present invention is not limited to this configuration. As illustrated inFIG. 7, the waveguide23may be disposed to be positioned between the plasmon generator24and the pole22f, and the end surface23bof the waveguide23may be disposed to form a portion of the head part end surface12a. Similarly, as illustrated inFIG. 8, the pole22fmay be positioned on the trailing side of the plasmon generator24, and the waveguide23may be disposed on the leading side of the plasmon generator24. Furthermore, as illustrated inFIG. 9, from a perspective of the ABS11aside, the pole22fmay include a protrusion portion protruding toward the leading side in V-shape, the V-shaped plasmon generator24may be disposed to contact the protrusion portion, and the waveguide23may be disposed on the leading side of the plasmon generator24. Furthermore, as illustrated inFIG. 10, from a perspective of the ABS11aside, the plasmon generator24may be positioned on the leading side more than the pole22fand may have a triangular shape protruding toward the side of the pole22f(trailing side) in V-shape. The waveguide23may be disposed at a position recessed more than the pole22fin the X axis direction (height direction) with a predetermined gap with the rear end surface of the pole22f.

In the thermally-assisted magnetic recording head having the configuration as illustrated inFIGS. 7 and 8, the distance between the plasmon generator24and the pole22fincreases. However, because the magnetic field intensity at the heating point by near-field light can be increased due to the installation of the magnetic field focusing parts25, information can be effectively written to the magnetic disk301.

Also, in the thermally-assisted magnetic recording head having the configuration as illustrated inFIG. 9, when the thickness of the plasmon generator24is excessively thin, the peak intensity of near-field light decreases. Accordingly, the plasmon generator24needs to have a predetermined thickness; but, this increases the distance between the plasmon generator24(near-field light generating portion NFP) and the pole22f. However, because the magnetic field intensity applied to the heating point can be increased due to the magnetic field focusing parts25, a writing magnetic field having the intensity that is necessary for magnetization reversal can be applied to the magnetic disk301.

Next, the function of the thermally-assisted magnetic recording head1according to the present embodiment having the above-described configuration is described.FIG. 11is a schematic view for describing thermally-assisted magnetic recording using a surface plasmon mode in a thermally-assisted magnetic recording head1according to the present embodiment.

As illustrated inFIG. 11, when information is written to the magnetic recording layer of the magnetic disk301by the electromagnetic transducer element22, first the laser light (waveguide light)63radiated from the laser diode60of the light source unit50propagates through the waveguide23. Next, the laser light (waveguide light)63that has propagated to the vicinity of the buffer portion40couples to the optical configuration formed by the waveguide23having the refractive index nWG, the buffer portion40having the refractive index nBFand the plasmon generator24formed of a conductive material such as a metal, and induces the surface plasmon mode on the propagation edge241of the plasmon generator24. In other words, the laser light63is coupled with the plasmon generator24in the surface plasmon mode. Actually, from the optical interfacial condition between the waveguide23, which is a core, and the buffer portion40, evanescent light is excited into the buffer portion40. Next, the surface plasmon mode is induced as the evanescent light and a fluctuation of charges excited at the metal surface (propagation edge241) of the plasmon generator24are coupled each other, and the surface plasmon is excited. Precisely, because the surface plasmon, which is the elementary excitation in this system, is coupled with the electromagnetic wave, the excited is a surface plasmon polariton. However, the surface plasmon polariton is abbreviated and simply referred to as surface plasmon hereinafter. This surface plasmon mode can be induced when the refractive index nBFof the buffer portion40is set to be smaller than the refractive index nWGof the waveguide23(nBF<nWG) and further a length of the buffer portion40(in the X axis direction), that is the length LBFof the coupling part between the waveguide23and the plasmon generator24(length HPGof the plasmon generator24in the X axis direction), and the thickness TBFof the buffer portion40(in the Z axis direction) are properly selected.

In the induced surface plasmon mode, a surface plasmon70is excited on the propagation edge241of the plasmon generator24and propagates on the propagation edge241along the direction of arrow71. The propagation edge241is not in contact with the pole22f, and therefore is not negatively affected by the pole22fthat has not been adjusted for efficiently exciting the surface plasmon. As a result, it becomes possible that the surface plasmon intentionally propagates on the propagation edge241.

As described above, when the surface plasmon70propagates in the direction of arrow71on the propagation edge241, the surface plasmon70, which is the electric field, is focused on the near-field light generating portion NFP on the near-field light generating end surface24a, which is a destination of the propagation edge241that extends to the head part end surface12a. As a result, near-field light72is generated from the near-field light generating portion NFP. The near-field light72is irradiated towards the magnetic recording layer of the magnetic disk301, reaches the surface of the magnetic disk301, and heats the magnetic recording layer portion of the magnetic disk301. Therefore, an anisotropic magnetic field (coercive force) of that portion decreases to a value at which the writing can be performed, and writing is performed by the magnetic field applied to that portion.

Herein, with the present embodiment, the plasmon generator24is positioned closer to the trailing side than the pole22fand therefore a portion where the writing magnetic field is applied immediately below the pole22fmoves relatively and is heated by the near-field light. Therefore, a magnetic field is not applied to the magnetic microparticles with unstable magnetization during the cooling process after the heating by the near-field light. Therefore, rapid magnetization reversal can occur in the adjacent magnetic domains on the magnetic disk301because of the magnetic field that was applied, and thus, the requirements for high recording density and sufficient S/N ratio can be satisfied.

Normally, the magnetic field generated from the pole22fspreads concentrically centering around the pole22fon the YZ plane. However, because of the installation of the magnetic field focusing parts25, the magnetic field generated from the pole22fdoes not spread on the YZ plane so that the magnetic field is focused on the portion where the magnetic field should be applied to achieve the writing of data to the magnetic disk301. Therefore, the writing magnetic field having the intensity that is necessary for the magnetization reversal is applied to the magnetic disk301.

Moreover, heat generation due to the generation of near-field light72occurs in the vicinity of the near-field light generating portion NFP of the near-field light generating end surface24a. However, because the plasmon generator24and the pole22fare positionally separated, the heat can be suppressed from escaping to the pole22fside. Therefore, degradation and the like of the pole22fdue to the heat that escapes to the pole22fside can also be suppressed.

Furthermore, when the respective gaps between the side surfaces23dand23fof the waveguide23and the magnetic field focusing parts25have the length of no less than the wavelength λLof the laser light entering into the waveguide23, a decay of the light propagating through the waveguide23is suppressed so that the preferred thermally-assisted effect can be obtained.

The thermally-assisted magnetic recording head with the above-described configuration can be manufactured as described below.

FIGS. 12A-12Eare schematic views illustrating steps for forming the plasmon generator24of the thermally-assisted magnetic recording head1according to the present embodiment. All of the drawings (FIGS. 12A-12D) are plan views illustrating a YZ plane from a perspective of the air bearing surface side.

As illustrated inFIG. 12A, the fifth insulating layer32eformed of Al2O3or the like is formed so as to cover the lower yoke layer22aformed of a magnetic material such as FeCo or the like and planarized using a polishing method such as chemical mechanical polishing (CMP). Two opening parts where the lower yoke layer22ais exposed are formed by a dry etching method such as an ion milling or the like. Then, the magnetic field focusing parts25formed of a soft magnetic material such as NiFe or the like are formed in the two opening parts by a plating method or the like.

Next, while the writing coil22dwinding around the first linkage layer22bis formed, the sixth insulating layers32fare formed between the windings of the writing coil22d. Further, the seventh insulating layer32gmade of Al2O3or the like is formed, and then the eighth insulating layer32his formed and planarized using a polishing method such as chemical mechanical polishing (CMP).

Next, as illustrated inFIG. 12B, an opening part is formed on the eighth insulating layer32hby a dry etching method such as an ion milling or the like. After the upper yoke layer22c, the second linkage layer22eand the pole22fare formed by, for example, a plating method or the like in the opening part, the ninth insulating layer32iis formed, and the waveguide23formed of, for example, TaOx or the like is formed by a sputtering or the like on the ninth insulating layer32i.

Next, as illustrated inFIG. 12C, the tenth insulating layer32jis formed so as to cover the pole22fand the waveguide23. A groove having a nearly V-shaped cross section is formed on the tenth insulating layer32jby a dry etching method such as an ion milling or the like so as to have a predetermined separation between the pole22fand the waveguide23.

Next, as illustrated inFIG. 12D, the plasmon generator24made of Au or the like is formed so as to fill the formed groove. Finally, the protective layer31is formed and then the head part12according to the present embodiment is manufactured.

The above-described embodiment is disposed for a clear understanding of the present invention, and is not disposed to limit the present invention. Therefore, each of the elements disclosed in the above-described embodiment also includes any design changes and equivalents thereof that belong to the technical scope of the present invention.

EXAMPLES

The present invention is described in further detail by presenting experimental examples. However, the present invention is in no way restricted to the following experimental examples and the like.

First Experimental Example

Simulation analysis experiments were performed as described below for the relationship between the installation position of the magnetic field focusing parts25and the decay rate of the laser light (waveguide light) propagating through the waveguide23in the thermally-assisted magnetic head1illustrated inFIGS. 4 and 5.

The simulation analysis experiments were performed using a three-dimensional finite-difference time-domain method (FDTD method) which is electromagnetic field analysis.

In the present experimental example, a model was used in which the waveguide23of the thermally-assisted magnetic recording head1was formed of Ta2O5(n=2.16) and the tenth insulating layer32jcontacting the side surfaces23dand23fof the waveguide23was formed of Al2O3(n=1.63). Also, in the present model, the respective widths of the pole22fand the waveguide23in the Y axis direction (track width direction) were set to be 400 nm, the respective heights of the pole22fand the waveguide23in the Z axis direction were set to be 400 nm, and the height of the plasmon generator24in the Z axis direction was set to be 200 nm.

Then, the magnetic field focusing parts25(the heights of the magnetic field focusing parts25in the Z-axis direction: 5 μm) are installed on the lower yoke layer22asuch that the upper end surfaces25bof the magnetic field focusing parts25are positioned above (on trailing side) the plasmon generator24. The decay rate (%) of the waveguide light was calculated by the simulation analysis while the respective gaps G were varied in a predetermined range (0-2.2 μm), and the relationship between the distances G and the decay rate (%) was determined. The respective gaps G are gaps in the Y axis direction (track width direction) between the side surface23dof the waveguide23and the magnetic field focusing part25and between the side surface23fof the waveguide23and the magnetic field focusing part25(, which are the distances G′ in the Y axis direction (track width direction) between the side surface222of the pole22fand the magnetic field focusing part25and between the side surface223of the pole22fand the magnetic field focusing part25). In addition, the simulation analysis was performed with the laser lights, radiated from the laser diode60, having the wavelength λLof 375 nm, 800 nm and 1700 nm. Table 1 illustrates the results of the above-described simulation analysis.

As illustrated in Table 1, when the respective gaps G between the side surfaces23dand23fof the waveguide23and the magnetic field focusing parts25are narrower than wavelength λLof the laser light radiated from the laser diode60by disposing the magnetic field focusing parts25closer to the waveguide23, it was determined that the light propagating through the waveguide23decayed. Therefore, it can be understood that the magnetic field focusing parts25are preferably installed such that the respective gaps G between the side surface23dof the waveguide23and the magnetic field focusing part25and between the side surface23fof the waveguide23and the magnetic field focusing part25are to have no less than the wavelength λLof the light radiated from the laser diode60and propagating through the waveguide23.

Second Experimental Example

Simulation analysis experiments were performed as described below for the magnetic field intensity of the magnetic field generated from the pole of the thermally-assisted magnetic recording head at a predetermined recording point.

The simulation analysis experiments were performed using a three-dimensional finite-difference time-domain method (FDTD method) which is electromagnetic field analysis.

In the thermally-assisted magnetic recording head of the present experimental example, a model was used in which the pole22fof the thermally-assisted magnetic recording head1illustrated inFIGS. 4 and 5was formed of FeCo alloy. Also, in the present model, the respective widths of the pole22fand the waveguide23in the Y axis direction (track width direction) were set to be 400 nm, the respective heights of the pole22fand the waveguide23in the Z axis direction were set to be 400 nm, the height of the plasmon generator24in the Z axis direction was set to be 200 nm, and a position that is 75 nm above from the upper end surface of the pole22fwas set to be a recording point. Furthermore, the number of windings in the writing coil22dwas 3, and the input current value was 40 mA. Note, the wavelength4of the laser light radiated from the laser diode60was set to be 800 nm.

Then, the magnetic field focusing parts25(the heights of the magnetic field focusing parts25in the Z axis direction: 5 μm) were installed on the lower yoke layer22asuch that the upper end surfaces25bof the magnetic field focusing parts25were positioned above (on trailing side of) the plasmon generator24. The magnetic field intensity (Hy) at the recording point was calculated by the simulation analysis while the respective gaps (distances) G′ were varied in a predetermined range (1-3 μm), and the relationship between the respective gaps (distances) G′ and the magnetic field intensity (Hy) was determined. The respective gaps (distances) G′ are gaps in the Y axis direction (track width direction) between the side surface222of the pole22fand the magnetic field focusing part25and between the side surface223of the pole22fand the magnetic field focusing part25. In addition, the simulation analysis was performed in a similar way as well for the thermally-assisted magnetic recording head that is disposed without the magnetic field focusing parts25.

FIG. 13illustrates the results of the above-described simulation analysis experiments.FIG. 13is a graph illustrating the results of the simulation analysis experiments. Note, inFIG. 13, the results of the simulation analysis experiments for the thermally-assisted magnetic recording head disposed with the magnetic field focusing parts25are illustrated with the solid line, and the results of the simulation analysis experiments for thermally-assisted magnetic recording head disposed without the magnetic field focusing parts25are illustrated with the broken line.

As illustrated inFIG. 13, it was determined that the more the magnetic field focusing parts25were positioned close to the pole22falong the Y axis direction (track width direction), the more the magnetic field intensity at the recording point was able to be increased. On the other hand, when the wavelength λLof the laser light radiated from the laser diode60is 800 nm as the present experimental example, and when the respective gaps in the Y axis direction between the magnetic field focusing parts25and the pole22fare less than 1 μm, as it is clear from the results of the first experimental example, the light propagating through the waveguide23decays and thereby the peak intensity of the near-field light may be decreased.

Third Experimental Example

In the model used in the above-described second experimental example, the respective gaps (distances) G′ in the Y axis direction between the magnetic field focusing parts25and the pole22fwere set to be 1 μm. Then, the magnetic field intensity at a recording point (a position of 75 nm upper (on trailing side) from the upper end part of the pole220was calculated by simulation analysis as in the second experimental example while the position of the upper end surfaces25bof the magnetic field focusing parts25were varied in a predetermined range, and the relationship between the position of the upper end surfaces25bof the magnetic field focusing parts25and the magnetic field intensity was determined. Also, simulation analysis was performed in a similar way as well for the thermally-assisted magnetic head disposed without the magnetic field focusing parts25.

FIG. 14illustrates the results of the above-described simulation analysis experiments.FIG. 14is a graph illustrating the results of the simulation analysis experiments. Note, inFIG. 14, (1) indicates the thermally-assisted magnetic recording head disposed without the magnetic field focusing parts25, (2) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the lower end part (a part positioned on the most-leading side) of the second linkage layer22e, (3) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the middle position of the total height of the pole22fand the second linkage layer22ein the Z axis direction, (4) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the near-field light generating portion NFP of the plasmon generator24, and (5) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the upper end part (a part positioned on the most-trailing side) of the plasmon generator24.

As illustrated inFIG. 14, it was determined that the more the upper end surfaces25bof the magnetic field focusing parts25approaches the upper position (on the trailing side), the more the magnetic field intensity at the recording point was increased, also that the magnetic field intensity at the recording point was maximized by setting the upper end surfaces25bof the magnetic field focusing parts25positioned at almost the same position as the near-field light generating portion NFP. On the other hand, when the upper end surfaces25bof the magnetic field focusing parts25are positioned above the near-field light generating portion NFP, the magnetic field intensity decreases. Accordingly, it can be understood that the upper end surfaces25bof the magnetic field focusing parts25are preferably positioned at almost the same position as the near-field light generating portion NFP.

Fourth Experimental Example

In the thermally-assisted magnetic recording head of the present experimental example, a model was used in which the pole22fof the thermally-assisted magnetic recording head1illustrated inFIG. 9was formed of FeCo alloy. Also, in the present model, the width of the pole22fin the Y axis direction (track width direction) was set to be 400 nm, the height of the pole22fin the Z axis direction was set to be 750 nm, the width of the waveguide23in the Y axis direction (track width direction) was set to be 400 nm, the height of the waveguide23in the Z axis direction was set to be 400 nm, the thickness of the near-field light generating portion NFP of the plasmon generator24in the Z axis direction was to be 35 nm, and a position of 75 nm upper from the near-field light generating portion NFP was set to be a recording point. Furthermore, the number of windings in the writing coil22dwas 3, and the input current value was set to be 40 mA. Note, the wavelength λLof the laser light radiated from the laser diode60was set to be 800 nm.

As in the second experimental example other than using the above-described model, the magnetic field intensity at the recording point was calculated by the simulation analysis while the gap (distance) was varied in a predetermined range (1-3 μm), and the relationship between the gap (distance) and the magnetic field intensity was determined. The gap (distance) is a gap in the Y axis direction (track width direction) between the vertex of the V-shaped protrusion portion of the pole22f(vertex positioned on the most-leading side) and the magnetic field focusing parts25. Similarly, the simulation analysis was performed in a similar way as well for the thermally-assisted magnetic recording head that is disposed without the magnetic field focusing parts25.

FIG. 15illustrates the results of the above-described simulation analysis experiments.FIG. 15is a graph illustrating the results of the simulation analysis experiments. Note, inFIG. 15, the results of the simulation analysis experiments for the thermally-assisted magnetic recording head disposed with the magnetic field focusing parts25are illustrated with the solid line, and the results of the simulation analysis experiments for thermally-assisted magnetic recording head disposed without the magnetic field focusing parts25are illustrated with the broken line.

As illustrated inFIG. 15, it was determined that the more the magnetic field focusing parts25were positioned close to the vertex of the V-shaped protrusion portion of the pole22falong the Y axis direction (track width direction), the more the magnetic field intensity at the recording point was able to be increased.

Fifth Experimental Example

In the model used in the above-described fourth experimental example, the gap (distance) in the Y axis direction between the magnetic field focusing parts25and the pole22fwere set to be 1 μm. Then, the magnetic field intensity at a recording point was calculated by simulation analysis as in the second experimental example while the position of the upper end surfaces25bof the magnetic field focusing parts25were varied in a predetermined range, and the relationship between the position of the upper end surfaces25bof the magnetic field focusing parts25and the magnetic field intensity was determined. Also, simulation analysis was performed in a similar way as well for the thermally-assisted magnetic head disposed without the magnetic field focusing parts25.

FIG. 16illustrates the results of the above-described simulation analysis experiments.FIG. 16is a graph illustrating the results of the simulation analysis experiments. Note, inFIG. 16, (1) indicates the thermally-assisted magnetic recording head disposed without the magnetic field focusing parts25, (2) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the lower end part (a part positioned on the most-leading side) of the second linkage layer22e, (3) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the middle position of the total height of the pole22fand the second linkage layer22ein the Z axis direction, (4) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the near-field light generating portion NFP of the plasmon generator24, and (5) indicates the thermally-assisted magnetic recording head in which the upper end surfaces25bof the magnetic field focusing parts25are positioned at the same height as the upper end part (a part positioned on the most-trailing side) of the plasmon generator24.

As illustrated inFIG. 16, it was determined that, the upper end surfaces25bof the magnetic field focusing parts25were positioned at the upper position (on the trailing side), the more the magnetic field intensity at the recording point was increased. Also, it was determined that the magnetic field intensity at the recording point was maximized when the upper end surfaces25bof the magnetic field focusing parts25are positioned at almost the same position as the near-field light generating portion NFP. On the other hand, when the upper end surfaces25bof the magnetic field focusing parts25are positioned above (on the trailing side of) the near-field light generating portion NFP, the magnetic field intensity decreases. Accordingly, it can be understood that the upper end surfaces25bof the magnetic field focusing parts25are preferably positioned at almost the same position as the near-field light generating portion NFP.