Abstract:
A thin film magnetic read/write head for use in magnetic data storage systems to enable writing of data to a magnetic data storage medium with the assistance of laser heating. The read/write head allows magnetic reading of data from the storage medium, and thermally assisted magnetic writing of data on the storage medium. A waveguide is provided in a write gap in the form of an optical circuit having a plurality of inputs and a single output at the air bearing surface (ABS) for concentrating laser light used for heating the storage medium during the write operation. The thermally assisted magnetic writing improves the thermal stability of the recorded data and usefulness thereof throughout a wide temperature range.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention relates in general to data storage systems such as disk drives. More particularly, the present invention relates to a thin film read/write head for use in magnetic data storage systems to enable writing of data to a magnetic data storage medium with the assistance of laser heating. The read/write head of the invention allows magnetic reading of data from the storage medium, and thermally assisted magnetic writing of data on the storage medium. The thermally assisted magnetic writing improves the thermal stability of the recorded data and usefulness thereof throughout a wide temperature range.  
       BACKGROUND OF THE INVENTION  
       [0002]     A conventional magnetic storage system typically includes a thin film magnetic head that includes a slider element and a magnetic read/write element. The head is coupled to a rotary actuator magnet and a voice coil assembly by a suspension and an actuator arm positioned over a surface of a spinning magnetic disk. In operation, a lift force is generated by the aerodynamic interaction between the magnetic head and the spinning magnetic disk, such that a predetermined flying height is maintained over a full radial stroke of the rotary actuator assembly above the surface of the spinning magnetic disk.  
         [0003]     Some factors that limit writing (or recording) on a magnetic disk at high data transfer rates (or frequencies) using conventional magnetic heads at wide temperature ranges are the increasing requirements for higher magnetic fields and field gradients to achieve a smaller and smaller bit size. High magnetic fields are difficult to achieve particularly with narrow tracks and miniaturized heads and at low temperature. As a result, thin film magnetic heads incorporating a laser device have been developed and used in magnetic recording devices for heating the magnetic media to reduce the coercive force of the media during the write operation.  
         [0004]     One example of a heat-assisted read/write head is shown in U.S. Pat. No. 6,016,290 entitled “Read/Write Head with Shifted Waveguide,” which is incorporated by reference herein.  FIGS. 1 and 2  of the &#39;290 patent, which are reproduced herein as  FIGS. 1 and 2 , illustrate an exemplary data storage system and head gimbal assembly, respectively, in which the instant invention may be utilized. More particularly,  FIG. 1  illustrates a conventional disk drive  10  including a head stack assembly (HSA)  12  and a stack of spaced apart data storage disks (magnetic recording media)  14  that are rotatable about a common shaft  15 . The head stack assembly  12  is rotatable about an actuator axis  16  in the direction indicated by arrow C. The head stack assembly  12  includes a number of actuator arms ( 18 A,  18 B,  18 C), which extend into respective spaces between the disks  14 . While only three actuator arms and disks are shown in  FIG. 1 , any desired number disks and actuator arms may be provided. The head stack assembly  12  further includes an E-shaped block  19  and a magnetic rotor  20  attached to the block  19  at an opposite position relative to the actuator arms. The rotor  20  cooperates with a stator (not shown) for rotating in an arc about the actuator axis  16 . Energizing a coil of the rotor  20  with, for example, a direct current in one polarity causes rotation of the actuator arms about the actuator axis  16 , thereby enabling the actuator arms to move across the disks  14 .  
         [0005]     A head gimbal assembly (HGA)  28  is secured to each of the actuator arms, as shown on actuator arm  18 A in  FIG. 1 . Referring now more particularly to  FIG. 2 , the HGA  28  includes a suspension  33  and a read/write head  35 . The suspension  33  includes a load beam  36  and a flexure  40  to which the read/write head  35  is secured. The read/write head  35  is comprised of a slider  47  secured to the free end of the load beam  36  by the flexure  40 . Thus, the read/write element  50  is supported by the slider  47 . In the example illustrated in  FIG. 2 , the read/write element  50  is secured to the trailing end  55  of the slider  47 . The slider  47  may also be referred to as a support element since it supports the read/write element  50 . The slider  47  can be any conventional or available slider.  
         [0006]     In the exemplary device disclosed in the &#39;290 patent, a laser diode  92  is secured to the slider  47  and is positioned over the read/write element  50  for optically coupling to a waveguide which passes through the read/write element. The laser beam propagating through the waveguide core heats a section of the track on the disk under the waveguide, thereby significantly reducing the disk coercivity. The magnetic field from the head at the medium adjacent a write gap is sufficiently large to reorient the domains of the data bits in the section of the track having reduced coercivity from the laser heating, thereby enabling the write element to write data within the track.  
         [0007]     Further details regarding the structure and operation of the exemplary heat-assisted device shown in  FIGS. 1 and 2  are provided in the &#39;290 patent and, therefore, will not be further described in detail herein. While the heat-assisted device of the &#39;290 patent, and other similar prior art devices, have improved the function of magnetic thin film heads in certain respects, further improvements in the structure and operation of such devices are still desired. Hence, the instant invention was developed in order to provide an improved heat-assisted thin film head for use in a magnetic hard disk drive.  
         [0008]     U.S. Pat. No. 5,295,122 entitled “Flying Head of a Magneto-Optical Recording Apparatus” discloses a magneto-optical recording apparatus in which a thin film magneto-optical head is provided separately from the slider.  FIGS. 13 and 14  of the &#39;122 patent disclose the use of an optical integrated circuit that is connected to a light source using three optical fibers. One of the optical fibers is used for writing or reading and the other two are for outputting light that has been read. The optical integrated circuit includes branching and connecting circuits that are coupled, using an integrated mirror portion, with a light waveguide path shown in  FIG. 14  of the &#39;122 patent. In contrast to the instant invention, which is directed to magnetic recording apparatus, the &#39;122 patent is limited to a magneto-optical recording apparatus. Thus, the &#39;122 patent is not concerned with and does not contemplate heat-assisted writing in a magnetic recording apparatus. Moreover, the overall structure of the magneto-optical head with optical integrated circuit disclosed in the &#39;122 patent has certain disadvantages with respect to the location and configuration of the optical integrated circuit. As a result, the teachings of the &#39;122 patent are not readily adaptable to magnetic recording applications, much less magnetic recording applications that incorporate heat-assisted writing.  
       SUMMARY OF THE INVENTION  
       [0009]     One aspect of the present invention is to satisfy the foregoing need by providing a read/write head having a magnetic reading element of high track density, combined with an improved heat-assisted magnetic write element.  
         [0010]     Another aspect of the invention is to provide a magnetic read/write head that incorporates an optical integrated circuit for heat-assisted writing operations.  
         [0011]     Another aspect of the invention is to provide an optical integrated circuit for heat-assisted writing having a configuration and orientation that provides certain advantages when incorporated into a magnetic read/write head.  
         [0012]     Another aspect of the invention is to provide an optical integrated circuit for heat-assisted magnetic writing having a configuration and orientation that enables the thickness of the magnetic read/write head to be minimized.  
         [0013]     A further aspect of the invention is to provide an optical integrated circuit for heat-assisted magnetic writing having a configuration and orientation that does not require the use of mirrors to focus or direct the light used for heat-assisted writing.  
         [0014]     In accordance with one embodiment, the invention provides a magnetic read/write head for use with magnetic storage medium, including a write section having an upper pole and lower pole defining a write gap therebetween, and an optical waveguide positioned in the write gap and including a plurality of input sections and a single output section. The input sections are optically coupled to a light beam source such that a plurality of light beams enter the plurality of input sections, respectively. The single output section outputs a light beam that provides thermally assisted writing of data on the magnetic storage medium. The plurality input sections are preferably located at a surface of the read/write head that is opposite to an air bearing surface thereof. This advantageously enables the thickness of the read/write head to be minimized.  
         [0015]     In accordance with another embodiment, the invention provides a magnetic read/write head for use with magnetic storage medium, including a write section including an upper pole and lower pole defining a write gap therebetween, and an optical waveguide positioned in the write gap and optically coupled to a light beam source. The optical waveguide outputs a light beam at an air bearing surface of the read/write head to provide heat-assisted writing of data on the magnetic storage medium. The optical waveguide has a waveguide core, and the width of the waveguide core at the air bearing surface is substantially wider than the width of the upper pole at the air bearing surface.  
         [0016]     The magnetic read/write head incorporates a laser beam and a waveguide to heat the recording medium in order to lower its coercive force during the write function. The lowered coercive force allows a relatively weak magnetic field to be used to write data in the recording medium which, upon cooling to ambient temperature, becomes magnetically hard and resistant to degradation over time.  
         [0017]     Another aspect of the present invention is to integrate an optical waveguide and a magnetic write element in a unique manner, without significantly enlarging the write gap or widening the data track width on the magnetic recording medium. The narrow data track width is preferably defined and controlled by an overlap region of the waveguide and the magnetic gap between the write poles. This results in a narrower data track than either the waveguide or the magnetic gap itself. The integration of the heat-assisted write element can be accomplished by, for example, mounting a heat source, such as a laser or light source on a slider, and by forming an optical waveguide circuit within the magnetic write gap of the write element. The structure is preferably formed using standard wafer fabrication processes. The waveguide directs a laser beam onto a target spot on or within the data storage medium, and is positionally shifted in the cross track direction (i.e., direction generally normal to the track) from the top write pole.  
         [0018]     The recording data track width is preferably determined by an overlap region of the waveguide and the top or upper write pole. This overlap region is defined at one end by the magnetic profile of the upper write pole edge, and at another end by the thermal profile of the waveguide edge. In one embodiment, a giant magneto-resistive (GMR) element is used as the read element, and has one edge aligned with the upper write pole edge and the other edge aligned with an edge of the waveguide. The head is capable of recording and reading a longitudinal medium, thereby enabling its use in conventional magnetic disk drives.  
         [0019]     The improved read/write head of the invention enables increased density of the magnetic recording medium and improves the servo writing process by reducing normally wasted dead space between tracks. The magnetic read operation provides a significantly better wide band signal-to-noise ratio than the optical read, which enhances the head performance especially at high frequencies. In addition, since the waveguide is aligned relative to the poles during wafer processing, the head requires minimal optical alignment, thereby making the head significantly simpler and less expensive to build as compared conventional read/write heads. Better writing capabilities are achieved at high track densities as compared to conventional magnetic recording systems.  
         [0020]     In accordance with another aspect of the invention, the waveguide is provided in the form of an optical circuit having a plurality of inputs, preferably located at the surface of the read/write head that is opposite to the air bearing surface (ABS), and a single output at the ABS for the laser light. The optical circuit includes at least one, and preferably a plurality of combination spots, where two branches of the optical circuit are combined into a single section for concentrating the light. As a result of the structure and orientation of the optical circuit, the optical circuit can extend beyond the back connection of the upper pole and emit a coherent wave to the disk from the ABS. The structure of the waveguide core prevents the light beam from scattering and enables the emitted light beam from the ABS to be as small as a writing bit. The structure of the optical circuit also enables the thickness of the read/write head to be minimized.  
         [0021]     In accordance with a further aspect of the invention, a read section of the read/write head includes a magneto-resistive element, and the width of the optical waveguide core at the air bearing surface (ABS) is substantially wider than the width of the upper write pole at the ABS.  
         [0022]     These and other features and advantages of the instant invention will be further understood by the following description of various exemplary embodiments of the invention and with reference to the appended drawings, in which: 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0023]      FIG. 1  is a fragmentary perspective view of a data storage system utilizing a read/write head according to the prior art;  
         [0024]      FIG. 2  is an enlarged perspective view of a head gimbal assembly (HGA) used in the prior art data storage system of  FIG. 1 ;  
         [0025]      FIG. 3  is a cross-sectional view of a read/write element forming part of a read/write head constructed in accordance with a preferred embodiment of the instant invention, and integrating a heat-assisted write section and a magnetic (GMR) read section;  
         [0026]      FIG. 4  is an enlarged, partial cross-sectional view of the read/write element of  FIG. 3 ;  
         [0027]      FIG. 5  is a front-view of the read/write element of  FIG. 3 , illustrating the optical waveguide circuit according to a preferred embodiment of the present invention;  
         [0028]      FIG. 5A  is an enlarged, partial front-view of the read/write element of  FIG. 5 ;  
         [0029]      FIG. 6A  is a perspective view of the read/write element of  FIG. 3  showing the optical waveguide according to the preferred embodiment of the present invention;  
         [0030]      FIG. 6B  is a perspective view of a read/write element showing an optical waveguide according to an alternative embodiment of the present invention;  
         [0031]      FIG. 7  is an ABS view of the read/write element of  FIG. 3 ; and  
         [0032]      FIG. 8  is a perspective view of an exemplary disk drive unit incorporating an embodiment of the heat-assisted read/write head of the instant invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]     The preferred embodiments of the thin film magnetic head and disk drive device will now be described with reference to the figures. It is noted that the magnetic head  110  of the instant invention can be incorporated into any suitable magnetic storage system, such as a storage system similar to that described above in connection with  FIGS. 1 and 2 . Due to the fact that the general overall structure of magnetic storage systems are well known, including head stack assemblies and head gimbal assemblies (as illustrated in  FIGS. 1 and 2 ), additional details on these elements are not provided herein. Instead, the following description of the invention will focus on the preferred embodiments of the thin film magnetic head, as it is understood that the head can be incorporated into any suitable magnetic storage system, such as but not limited to, the types shown in  FIGS. 1, 2  and  8  herein.  
         [0034]      FIG. 3  shows a thin film magnetic head  110  for use in a magnetic disk drive device and constructed in accordance with a preferred embodiment of the instant invention. As shown in  FIG. 3 , the head  110  primarily includes a slider  114  and a read/write element  162  that constitutes a hybrid transducer which integrates a thermally assisted magnetic write section and a magnetic read section.  
         [0035]     The magnetic read section includes a lower shield layer  116  preferably made of a material that is both magnetically and electrically conductive. For example, the lower shield  116  can have a nickel-iron composition, such as Permalloy, or a ferromagnetic composition with high permeability. The thickness of the lower shield  116  is preferably in the range of approximately 0.5 microns to approximately 14 microns, and more preferably in the range of approximately 1 micron to approximately 4 microns.  
         [0036]     The magnetic read section includes a read element  120  formed within a read gap defined between the lower shield  116  and an upper shield  118 . In this exemplary embodiment, the read section incorporates a giant magnetoresistive (GMR) element. An insulating layer  164 , which is preferably made of aluminum oxide or silicon nitride, for example, is formed within the read gap, over substantially the entire length of the read element  120 , but preferably not at the air bearing surface (ABS)  138  of the read element  120 .  
         [0037]     The giant magnetoresistive (GMR) read element  120  can be formed, for example, by depositing a plurality of alternating ultra-thin layers of magnetically conductive and nonconductive materials, such as Permalloy (Ni 80 Fe20) and copper (Cu), each layer being approximately 10 to 30 angstroms thick. The electric resistance of the GMR element  120  fluctuates when exposed to a time-varying magnetic flux.  
         [0038]     The read section also includes an upper shield layer  118 , that can be formed over substantially the entire insulating layer  164  (see  FIG. 4 ). Preferably, the upper shield  118  is made of an electrically and magnetically conductive material that can be similar or equivalent to that of the lower shield  116 . The thickness of the lower shield  118  can be, optionally but not necessarily, substantially similar or equivalent to that of the lower shield  116 . It is noted that the read section is not limited to GMR elements and, instead, can be formed of any other available and suitable magnetic elements, depending on the particular application in which the invention is employed.  
         [0039]     A read circuit  122  is connected to the lower shield  116  and the upper shield  118 , such that during a read mode the read circuit  122  sends a sensing electric current IR through the GMR element  120 . The read-sense current IR flows perpendicularly through the GMR element  120 , thus avoiding the along the plane electro-migration problems and magnetic-biasing due to paralleled-current problems associated with some prior art designs based on CIP operation (Current In the Plane mode). In this regard, reference is made to U.S. Pat. No. 5,576,914, which is incorporated herein by reference.  
         [0040]     The write section of the read/write head  162  includes a lower pole layer  124 , an upper pole layer  126  and a write gap therebetween. In accordance with the invention, an optical waveguide  128  is formed at least partially within the write gap between the lower pole  124  and upper pole  126 . A write element is provided that has a pole tip height dimension, referred to as “throat height” (“ABS”), formed by lapping and polishing the pole tip, and a zero throat level where the pole tip of the write head transitions to a back region. A pole tip region ( 146  in  FIG. 5 ) is defined as the region between the ABS and the zero throat level. Preferably, the optical waveguide  128  includes waveguide cladding ( 148  in  FIG. 5A ) that boarders two sides of the waveguide core ( 152  in  FIG. 5A ) within the pole tip region  146  and completely surrounds the waveguide core  152  above the pole tip region  146 . In the embodiment illustrated in  FIG. 3 , the lower pole  124  is not the same as the upper shield  118 . However, in other embodiments, the lower pole  124  can be the same as the upper shield  118 .  
         [0041]     The optical waveguide core  152  is preferably formed within the write gap and along substantially the entire length of the lower pole  124 . The waveguide core  152  is preferably formed of a material such as TiO2, SiO2 or Al 2 O3 that has a high optical index of refraction. The waveguide cladding  148  is preferably formed of a material, such as TiO2, SiO2 or Al 2 O3, with a low index of refraction. A light beam  134  is directed into input ends  128   a  of the optical waveguide  128  by, for example, the use of a light beam source and an optical fiber  136 . The light beam  134  is preferably a laser beam that provides the required energy to heat a target spot on a data layer within the disk  112  to a critical temperature. This heating lowers the coercive force (Hc) of the data layer temporarily in order to assist with erasing and writing data. In one embodiment, the critical temperature is close to the Curie temperature of the data layer. As the critical temperature is approached or reached, the field strength in the data layer magnetic domain is greatly reduced. An external magnetic field is generated by the field in the target domains, as desired, to record a “1” or a “0” data bit. Data is recorded, under control of the write circuit  132 , by orienting the magnetization of a spot or domain, directionally, for example in either an up or a down direction. The read element  120  reads the recorded data by measuring the change in the resistance of the GMR element.  
         [0042]      FIG. 4  shows an enlarged partial view of the read/write head  162  of  FIG. 3 , in order to more clearly show the lower shield  116 , read element  120 , insulating layer  164 , upper shield  118 , separating layer  142 , lower pole  124 , optical waveguide  128 , coil  130 , upper pole  126 , air bearing surface (ABS)  138  and disk  112 .  
         [0043]     As shown most clearly in  FIG. 5 , the optical waveguide  128  preferably has a plurality of waveguide core portions  152  and a plurality of waveguide combination spots  128   b  at which multiple light beams  134  are combined or concentrated. The optical waveguide  128  also preferably includes a plurality of input ends  128   a  that each receive a light beam  134  from the light beam source via the optical fiber  136 . The plurality of input ends are preferably located at a surface of the read/write head that is opposite to the ABS  138 , thereby enabling the thickness of the read/write head to be minimized. Thus, the waveguide  128  defines an optical combiner/splitter. Optical waveguide  128  preferably also includes parallel sides  156  and  158 , and its width is substantially constant along the height-direction (See  FIG. 5A ).  FIG. 5A  shows an enlarged partial view of the optical waveguide  128  near the ABS  138  and illustrating how the light beams  134  are combined at combination spot  128   b  to a single light beam  160  for heat-assisted writing at the output end  154  of the optical circuit  128 . Element  150  in  FIG. 5A  represents an overcoat layer.  
         [0044]      FIG. 6A  provides a perspective view of the slider  114  and read/write head  162  of this embodiment, which further illustrates the preferred configuration of the optical circuit  128 . The input ends  128   a  of the optical circuit  128  are preferably enlarged at the location of the optical fiber to facilitate coupling therewith and then have a reduce size to fit within the write gap formed between the upper pole  126  and lower pole  124 .  FIG. 6B  shows an alternative embodiment of the invention, in which the optical circuit  128  includes only two input sections  128   a  and one output section  154  (i.e., a 2-to-1 waveguide). Thus, in this alternative embodiment, the optical circuit  128  has only a single combination section that combines the light prior to reaching the ABS. In other embodiments, the light from the plurality of input sections can be combined at or near the ABS without the need for a specific combination section. Thus, while the invention involves a plurality of input sections for the heating light, the invention is not limited to any number of combination sections, as long as the light is concentrated from the plurality of input sections at or near the ABS for delivery to the disk in a manner that enables heat-assisted writing. A significant advantage that is achieved by the invention is that the configuration of the optical circuit enables the thickness of the slider (with the head) to be minimized. Another significant advantage is that the configuration of the optical waveguide enables the waveguide to pass or go around the back connection  140  of the upper pole  126  (as seen most clearly in  FIG. 5 ), and emit a coherent wave to the disk  112  from the ABS.  
         [0045]     As shown in  FIG. 7 , which represent an ABS view of the slider  114  and read/write head  162  of this embodiment, the optical waveguide core  128  has a rectangular cross sectional surface area. The optical waveguide  128  is designed to combine and concentrate the light beams  134  from the input ends  128   a  in order to provide a sharp-edged heat spot on the disk  112 . While the preferred shape and cross-section of the optical waveguide  128  is shown in  FIGS. 3-7 , other shapes and cross-sectional configurations can be employed (e.g., circular, square, enlongated, etc.).  
         [0046]     With reference to  FIGS. 5A and 7 , the optical waveguide core is defined by two side edges  156  and  158 . In a preferred embodiment, the two side edges  156  and  158  are flat and parallel. At or close to the air bearing surface (ABS)  138 , the optical waveguide core preferably has substantially the same thickness (“TABS”) as the waveguide cladding  148 , such that the write gap has a uniform thickness. Preferably, the thickness TABS can range between approximately 1 micron and approximately 0.02 micron.  
         [0047]     With reference to  FIG. 3, 4  and  7 , the upper pole layer  126  can be made of an electrically and magnetically conductive material that is similar or equivalent to that of the lower shield layer  116  and the lower pole layer  124 . The thickness of the upper pole layer  126  can be substantially the same (or the upper pole layer  126  can optionally be different from) that of the lower shield layer  116 . The upper pole layer  126  overlays part of the optical waveguide core and optical waveguide cladding along the throat height region. The upper pole layer  126  includes a pole tip region  146  and a yoke region  144 . The pole tip region  146  defines the width at ABS as the writing width of this head. The yoke region  144  is to connect between the lower pole layer  124  and the pole tip region  146  of the upper pole layer  126 . In this embodiment, the waveguide core has a width at ABS (OW) that is wider (preferably only a little wider) than the width of the pole tip region  146  of the upper pole layer  126  at ABS.  
         [0048]     In operation, the laser beam  134  propagating through the core of the optical waveguide  128  heats a section of the track of the disk  112 . The track has a width underneath the optical waveguide  88 , and the heating significantly reduces the coercive force of the disk  112 . The magnetic field from the read/write head  162  at the medium adjacent the write gap is sufficiently large to reorient the domains of the data bits in the section of the track having reduced coercive force from laser heating, thereby enabling the write element to write data within the track of the disk  112 . Only the region of the track  112  under the write gap (the optical waveguide core portion  154 ) can be overwritten because the magnetic field from the write gap applies only to its underneath region.  
         [0049]     The placement of the optical waveguide core portion  152  of the optical waveguide core within the write gap, combined with the extensions  152  of the optical waveguide core, and the location of the wave combination spot  128   b  (or spots) shown on FIG. SA beyond the overlap region, presents one of the important aspects of this embodiment of the invention. This design allows the magnetic and thermal gradients to interact concurrently to write data on the track. In other words, as the disk  112  travels in a direction relative to the read/write head, the heat generated on the data track as the laser beam is transmitted through the optical waveguide core, is sufficient to adequately reduce the coercive force of the disk for writing and does not dissipate before the magnetic field is applied.  
         [0050]     As has been described above, the optical waveguide core preferably has several optical combiners or combination spots  128   b , such as the combinations spot  128   b  shown in  FIG. 5A , that combine the light from waveguide core portions  152  into the output end  154  of the waveguide core. As a result of this structure, the light is concentrated as the light travels from the input ends  128   a  of the optical circuit  128  to the ABS. Therefore, in accordance with the invention, the waveguide can pass the back connection  140  of the upper pole  126 , and emit a coherent wave to the disk  112  from the ABS. Thus, the invention prevents the light beam from scattering and concentrates the light beam from the waveguide core to a point that is as small as the writing bit in the disk  112 .  
         [0051]      FIG. 8  shows an exemplary disk drive unit (HDD) incorporating the thin film magnetic head  110  of the instant invention. The HDD includes a housing  108 , a disk  101 , a spindle motor  102 , a VCM  107  with an HGA 3 having a heat-assisted read/write head  110  constructed in accordance with the instant invention. Because the structure, operation and assembly processes of disk drive units are well known to persons of ordinary skill in the art, further details regarding the disk drive unit are not provided herein so as not to obscure the invention.  
         [0052]     While the preferred forms and embodiments of the invention have been illustrated and described herein, various changes and/or modifications can be made within the scope of the instant invention. Thus, the embodiments described herein are meant to be exemplary only and are not intended to limit the invention to any of the specific features thereof, except to the extent that any of specific features are expressly recited in the appended claims.