Patent Publication Number: US-11657835-B2

Title: Magnetic head with assisted magnetic recording comprising an electrically conductive, non-magnetic material

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 17/141,068, filed Jan. 4, 2021, which is a continuation of U.S. patent application Ser. No. 16/252,419, filed Jan. 18, 2019, which application claims benefit of U.S. Provisional Patent Application Ser. No. 62/743,110, filed Oct. 9, 2018, each of which is herein incorporated by reference. 
    
    
     FIELD 
     The present disclosure relates generally to the field of magnetic recording heads, and particular to assisted magnetic recording. 
     BACKGROUND 
     Disk drives comprise a disk and a head connected to a distal end of an actuator arm which is rotated about a pivot by a voice coil motor (VCM) to position the head radially over the disk. The disk comprises a plurality of radially spaced, concentric tracks for recording user data sectors and servo sectors. The servo sectors comprise head positioning information (e.g., a track address) which is read by the head and processed by a servo control system to control the actuator arm as it seeks from track to track. 
       FIG.  1    shows a prior art disk  902  comprising a number of servo tracks  904  defined by servo sectors  906   0 - 906   N  recorded around the circumference of each servo track. Each servo sector  906   i  comprises a preamble  908  for storing a periodic pattern, which allows proper gain adjustment and timing synchronization of the read signal, and a sync mark  910  for storing a special pattern used to symbol synchronize to a servo data field  912 . The servo data field  912  stores coarse head positioning information, such as a servo track address, used to position the head over a target data track during a seek operation. Each servo sector  906   i  further comprises groups of servo bursts  914  (e.g., N and Q servo bursts), which are recorded with a predetermined phase relative to one another and relative to the servo track centerlines. The phase based servo bursts  914  provide fine head position information used for centerline tracking while accessing a data track during write/read operations. A position error signal (PES) is generated by reading the servo bursts  914 , wherein the PES represents a measured position of the head relative to a centerline of a target servo track. A servo controller processes the PES to generate a control signal applied to a head actuator (e.g., a voice coil motor) in order to actuate the head radially over the disk in a direction that reduces the PES. 
       FIG.  2 A  illustrates a conventional disk drive  810  used for data storage. A disk media (i.e., a magnetic disk)  850  is attached to a spindle motor and hub  820 . The spindle motor and hub  820  rotate the media  850  in a direction shown by arrow  855 . A head stack assembly (HSA)  815  includes a carriage  820  and a voice coil motor (VCM)  825 . A first end of an actuator arm  870  is supported by the carriage  820 . A second end of the actuator arm  870  supports a head-gimbal assembly (HGA)  830 . The HSA  815  positions the actuator arm  870  using the voice coil motor (VCM)  825  and a pivot shaft and bearing assembly  860  over a desired data track  840  of the disk media  850  to read and/or write data from and/or to the data track  840 . 
       FIG.  2 B  illustrates the details of the HGA  830  located over the data track  840 . The HGA  830  includes a slider  880  located above the data track  840  and a magnetic head  600  (also called a recording head or a reading and recording head) located on the slider  880 . The magnetic head  600  contains a recording head (also called a magnetic recording transducer, a writing head or a writer)  660 . The magnetic head  600  may also contain a reading head (also called a magnetic reading transducer, a reading element or a reader)  610 . The media  850  and the track  840  move under the slider  880  in a down-track direction shown by arrow  842 . The cross-track direction is shown by arrow  841 . The recording head  660  has a leading edge  891  and a trailing edge  892 . In this embodiment, the trailing edge  892  of the recording head  660  is the final portion of the recording head  660  that writes (i.e., records) data onto the data track  840  as the media  850  moves under the slider  880  in the down-track direction  842 . 
       FIG.  3    illustrates a side view of the disk drive  810  shown in  FIG.  2 A . At least one disk media  850  (e.g., plural disk media  850 ) are mounted onto the spindle motor and hub  820 . The HSA  815  supports at least one actuator arm  870  (e.g., plural arms  870 ). Each actuator arm  870  carries a suspension  875  and the slider  880 . The slider  880  has an air bearing surface (ABS) facing the media  850 . When the media  850  is rotating and the actuator arm  870  is positioned over the media  850 , the slider  880  slides above the media  850  by aerodynamic pressure created between the slider ABS and the surface of media  850 . 
     Data is typically written to the disk by modulating a write current in an inductive coil to record magnetic transitions onto the disk surface in a process referred to as saturation recording. During readback, the magnetic transitions are sensed by a read head and the resulting read signal demodulated by a suitable read channel. However, as conventional perpendicular magnetic recording (PMR) approaches its limit, further growth of the areal recording density becomes increasingly challenging. 
     SUMMARY 
     According to an aspect of the present disclosure, a magnetic head includes a main pole configured to serve as a first electrode, an upper pole containing a trailing magnetic shield configured to a serve as a second electrode, and an electrically conductive portion located in a trailing gap between the main pole and the trailing magnetic shield. The electrically conductive portion is not part of a spin torque oscillator stack, and the electrically conductive portion comprises at least one electrically conductive, non-magnetic material layer. The main pole and the trailing magnetic shield are electrically shorted by the electrically conductive portion across the trailing gap between the main pole and the trailing magnetic shield such that an electrically conductive path is present between the main pole and the trailing magnetic shield through the electrically conductive portion. 
     According to another aspect of the present disclosure, a method of operating a magnetic recording head comprises providing a current between a main pole and an upper pole containing a trailing magnetic shield through an electrically conductive portion located in a trailing gap between the main pole and the trailing shield while applying a magnetic field to the main pole from a coil to record data to a magnetic disk. The electrically conductive portion is not part of a spin torque oscillator stack, and the electrically conductive portion comprises at least one electrically conductive, non-magnetic material layer. 
     According to yet another aspect of the present disclosure, a method of forming a magnetic head comprises forming a main pole over a substrate, forming an electrically conductive, non-magnetic material layer over the main pole, forming a trailing magnetic shield directly on a trailing sidewall of the electrically conductive, non-magnetic material layer, and forming an air bearing surface (ABS) of the magnetic head by lapping portions of the main pole and the trailing magnetic shield. An electrically conductive path is present between the main pole and the trailing magnetic shield through the electrically conductive, non-magnetic material layer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    shows a top view of prior art disk including a plurality of servo tracks defined by servo sectors. 
         FIG.  2 A  illustrates a top view of a conventional hard disk drive and  FIG.  2 B  schematically illustrates a top view of a head-gimbal assembly of the hard disk drive of  FIG.  2 A . 
         FIG.  3    illustrates a side view of the conventional hard disk drive of  FIG.  2 A . 
         FIG.  4    is an in-track vertical cross-sectional view of an exemplary magnetic head of the present disclosure. 
         FIG.  5 A  is an in-track vertical cross-sectional view of a first exemplary recording head according to a first embodiment of the present disclosure. 
         FIG.  5 B  is an air bearing surface (ABS) view of a portion of the first exemplary recording head according to the first embodiment of the present disclosure. 
         FIG.  6    is an in-track vertical cross-sectional view of a second exemplary recording head according to a second embodiment of the present disclosure. 
         FIG.  7 A  is an in-track vertical cross-sectional view of a third exemplary recording head according to a third embodiment of the present disclosure. 
         FIG.  7 B  is an ABS view of a portion of the third exemplary recording head according to the third embodiment of the present disclosure. 
         FIGS.  8 A- 8 F  are sequential vertical cross-sectional views of a first exemplary structure for manufacture of the first exemplary recording head according to the first embodiment of the present disclosure. 
         FIGS.  9 A- 9 E  are sequential vertical cross-sectional views of a second exemplary structure for manufacture of the second exemplary recording head according to the second embodiment of the present disclosure. 
         FIGS.  10 A- 10 C  are sequential vertical cross-sectional views of a third exemplary structure for manufacture of the third exemplary recording head according to the third embodiment of the present disclosure. 
         FIG.  11    shows magnetization M, bias current I, and the current induced Ampere&#39;s field in the main pole and in the trailing shield in the vicinity of a trailing gap according to an embodiment of the present disclosure. 
         FIG.  12    shows finite element model (FEM) simulation results of the bias current distribution and the Ampere&#39;s field (MP) produced by 5 mA of the bias current through the main pole according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     As discussed above, the present disclosure is directed to magnetic recording heads employing Ampere field enhancement and methods of manufacturing such magnetic recording heads. 
     The drawings are not drawn to scale. Multiple instances of an element may be duplicated where a single instance of the element is illustrated, unless absence of duplication of elements is expressly described or clearly indicated otherwise. Ordinals such as “first,” “second,” and “third” are employed merely to identify similar elements, and different ordinals may be employed across the specification and the claims of the instant disclosure. The same reference numerals refer to the same element or similar element. Unless otherwise indicated, elements having the same reference numerals are presumed to have the same composition. As used herein, a first element located “on” a second element can be located on the exterior side of a surface of the second element or on the interior side of the second element. As used herein, a first element is located “directly on” a second element if there exist a physical contact between a surface of the first element and a surface of the second element. 
     As used herein, a “layer” refers to a material portion including a region having a thickness. A layer may extend over the entirety of an underlying or overlying structure, or may have an extent less than the extent of an underlying or overlying structure. Further, a layer may be a region of a homogeneous or inhomogeneous continuous structure that has a thickness less than the thickness of the continuous structure. For example, a layer may be located between any pair of horizontal planes between, or at, a top surface and a bottom surface of the continuous structure. A layer may extend horizontally, vertically, and/or along a tapered surface. A substrate may be a layer, may include one or more layers therein, or may have one or more layer thereupon, thereabove, and/or therebelow. 
     As used herein, an “electrically conductive material” refers to a material having electrical conductivity greater than 1.0×10 5  S/cm. As used herein, a “metallic material” refers to a conductive material including at least one metallic element therein. As used herein, an “electrically insulating material” or a “dielectric material” refers to a material having electrical conductivity less than 1.0×10&#39;S/cm. As used herein, a “semiconducting material” refers to a material having electrical conductivity in the range from 1.0×10&#39;S/cm to 1.0×10 5  S/cm. All measurements for electrical conductivities are made at the standard condition. 
     Referring to  FIG.  4   , an in-track vertical cross-sectional view of an exemplary magnetic head  600  of one embodiment of the present disclosure is illustrated. The magnetic head  600  is configured for magnetic recording employing a spin torque oscillator (STO). The magnetic head  600  is positioned over a recording track  840  on a disk media. The magnetic head  600  comprises, from the leading side of the head (i.e., the left side of  FIG.  4   ), a reading head  610  and a recording head  660 . The reading head comprises a lower reading shield  620 , a read sensor  650  (i.e., a reading element), and an upper reading shield  690 . The read sensor  650  can include a tunnel magnetoresistance (TMR) device, a giant magnetoresistance (GMR) device, or the like. 
     The recording head  660  can comprise a record element  200  that includes a spin torque oscillator (STO) element, an optional auxiliary pole  202 , a main pole  220 , a magnetic coil  225  that is wound around the main pole  220 , and a trailing shield  280  which may be integrated with an upper pole  285 . The record element  200  is formed in a gap between the main pole  220  and the trailing shield  280 . The main pole  220  and trailing shield  280  serve as first and second electrodes for flowing electrical current through the record element  200  during recording (i.e., writing). A bias circuitry  290  can be electrically connected to the main pole  220  and the upper pole  285 , such as to the end portions of the main pole and the upper pole  285  distal from the ABS and the record element  200 . The bias circuitry  290  may include a voltage or current source (or a connection to an external voltage or current source) and one or more switching devices, such as transistors or relays which can switch the voltage or current on and off. The bias circuitry  290  is configured to provide a current or voltage to the main pole  220  and the upper pole  285 . For example, the bias circuitry  290  may provide a current between the main pole  220  and the upper pole  285 /trailing shield  280  that flows through the record element  200 . An insulating material portion  270  is provided around the magnetic coil  225  between the main pole  220 , the trailing shield  280  and the upper pole  285 . An electrically insulating material layer  272  can be provided between end portions of the main pole  220  and the upper pole  285  where the bias circuitry connections (i.e., electrical contacts  291 ,  292  attached to the ends of the main pole and upper pole respectively) are made (i.e., distal from the ABS). 
     During operation of the recording head  660 , if perpendicular magnetic recording is employed, a magnetic field emitted from the main pole  220  passes through a magnetic recording layer (e.g., hard magnetic layer)  710  and a soft magnetic underlayer  720  of the recording track  840  of the disk media  850 , and returns to the auxiliary pole  202 . A magnetization pattern (represented by arrows) is recorded in the magnetic recording layer  710 . In an implementation of a MAMR system, the magnetization pattern is recorded when electrical current flows between the main pole  210  and the upper pole  285  which is physically and electrically connected to trailing shield  280 , and, in one embodiment, a high-frequency magnetic field from the STO element of the record element  200  is applied to the recording track  840  to temporarily reduce the coercivity of the magnetic recording layer  710 . 
       FIGS.  5 A and  5 B  show magnified views of a first exemplary embodiment of the recording head  660  of a system that includes a record element  200  according to a first embodiment of the present disclosure. The main pole  220  is configured to emit a recording magnetic field for affecting the magnetic medium of the magnetic recording layer  710  (shown in  FIG.  4   ). When electrical current passes through the magnetic coil  225 , the magnetic field generated by the electrical current through the magnetic coil  225  magnetizes the soft magnetic material of the main pole  220 , and the magnetic field is guided by through the main pole  220  and the trailing shield  280  to complete a magnetic loop. 
     As shown in  FIG.  5 B , the record element  200  includes a spin torque oscillator (STO) stack  250  located on a trailing sidewall of the main pole  220  in a gap between the main pole and the trailing shield. Side magnetic shields (also known as wrap around shield, WAS)  206  can be provided around the main pole  220  without physically contacting the main pole  220 . A gap  205  which can be filled with a non-magnetic material, such as a dielectric material, for example aluminum oxide, is provided between the main pole  220  and each of the seed layer  207  and the side magnetic shields  206 . The side magnetic shields  206  can be provided on the sides of the main pole  220 , and may contact an electrically conductive seed layer  207  and the trailing shield  280 . The trailing shield  280  is a magnetic shield located on a trailing sidewall of the spin torque oscillator  250  stack. 
     The main pole  220  is configured to serve as a first electrode of an electrical circuit, and the trailing shield  280  is configured to serve as a second electrode of the electrical circuit. The electrical circuit is biased by the bias circuitry  290 , which is configured to provide electrical current between the main pole  220  and the trailing shield  280 /upper pole  285  through the record element  200  in two opposite directions, which correspond to the two opposite magnetization directions that the record element  200  can induce in the magnetic medium to be recorded. An air bearing surface (ABS) of the magnetic head  600  includes planar surfaces of the main pole  220 , the spin torque oscillator  250 , and the magnetic shield as embodied as the trailing shield  280 . Thus, the spin torque oscillator is exposed to the ABS. The planar surfaces can be within a same two-dimensional plane that provided by lapping during a manufacturing process. 
     As shown in the inset in  FIG.  5 A , according to an aspect of the present disclosure, a first electrically conductive path ECP 1  is present through the spin torque oscillator  250  stack between the first electrode (as embodied as the main pole  220 ) and the second electrode (as embodied as the trailing shield  280 ). A second electrically conductive path ECP 2  in a parallel connection with the first electrically conductive path ECP 1  is present between the first electrode and the second electrode through a conductive material portion  360 . Preferably but not necessarily, the conductive material portion  360  includes an electrically conductive, non-magnetic metal or a non-magnetic metallic alloy. In one embodiment, the conductive material portion  360  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. 
     In one embodiment, the conductive material portion  360  is located in the gap between the main pole  220  and the trailing shield  280 . In one embodiment, the conductive material portion  360  is not exposed to the ABS and is spaced from the ABS by a portion of the trailing shield  280  and or by the STO  250 . In one embodiment, the conductive material portion  360  contacts a leading surface of the trailing shield  280 . In one embodiment, the conductive material portion  360  includes a non-magnetic electrically conductive material, which can be a non-magnetic metal such as copper, tungsten, ruthenium, chromium and/or any other non-magnetic metal or a non-magnetic metallic alloy. 
     In one embodiment, a conductive layer stack  350  can also be provided in the gap between the main pole  220  and the trailing shield  280  within the second electrically conductive path ECP 2 . The conductive layer stack  350  can have a same set of component layers as the spin torque oscillator  250  stack, and can be spaced from the spin torque oscillator  250  stack by a dielectric spacer  310 . The dielectric spacer  310  includes a dielectric material such as aluminum oxide, silicon oxide, and/or silicon nitride, and prevents the conductive layer stack  350  from functioning as another spin torque oscillator stack. In one embodiment, the conductive material portion  360  causes a predominant portion of the magnetic flux through the main pole  220  to flow through the spin torque oscillator  250  stack, and significantly reduces the magnetic flux through the conductive layer stack  350 . For this reason, spin torque effect in the conductive layer stack  350  is much less than the spin torque effect in the spin torque oscillator  250  stack. 
     In one embodiment, the conductive layer stack  350  and the spin torque oscillator  250  stack can be located directly on the trailing sidewall of the main pole  220  in the trailing gap  222  between the main pole and the trailing shield  280 . The conductive material portion  360  can be located on a trailing sidewall of the conductive layer stack  350 . In one embodiment, an interface between the spin torque oscillator  250  stack and the magnetic shield (as embodied as the trailing shield  280 ) can be within a same plane as an interface between the conductive layer stack  350  and the conductive material portion  360 . 
     Referring to the inset in  FIG.  5 A , the main pole  220  can have a trailing edge taper such that the trailing edge of the main pole and the trailing gap  222  between the main pole  220  and the trailing shield  280  can be tapered (i.e., slanted) in a non-perpendicular direction compared to the ABS. For example, the trailing edge of the main pole  220  and the trailing gap  222  can extend in a direction which is inclined with respect to the plane of the ABS by an angle of 10 to 80 degrees, such as 30 to 60 degrees. The trailing shield  280  can have a “bump” structure at a throat portion which results in the narrowing of the trailing gap  222  adjacent to the ABS where the STO  250  is located. The bump structure which defines a short effective trailing shield throat height (eTH) that may range from 20 nm to 150 nm. The shortest dimension in the direction into the air bearing surface (ABS) that determines the current path can be defined by either the eTH (if the bump material is non-conducting), or back edge position of the conducting trailing gap (if it is patterned and shorter than eTH), or both (if the two coincide). 
     Above the STO  250  and above the bump in the trailing shield  280 , the trailing gap  222  is wider (i.e., has a larger width) than the width of the trailing gap  222  adjacent to the bump (i.e., the throat portion) of the trailing shield  280 . The conductive layer stack  350  and the conductive material portion  360  are located in the wider portions of the trailing gap  222  above the throat portion of the trailing shield  280  while the STO  250  stack is located adjacent to the throat portion of the trailing shield in the narrower portion of the trailing gap  222 . Thus, the conductive layer stack  350  and the conductive material portion  360  electrically short the main pole  220  and the trailing shield  280  across the trailing gap  222 . 
     The electrical bias circuitry  290  is configured to flow electrical current between the first electrode (embodied as the main pole  220 ) and the second electrode (embodied as the trailing shield  280 ) through the first electrically conductive path ECP 1  and the second electrically conductive path ECP 2  in a forward direction and in a reverse direction depending on selection of a bias direction by the switching elements of the electrical bias circuitry  290 . 
     In one embodiment, the spin torque oscillator  250  stack is configured to generate a high-frequency magnetic field which is superimposed with the recording magnetic field to record data to the magnetic medium when current flows through the first and second electrically conductive paths (ECP 1 , ECP 2 ). The spin torque oscillator  250  stack can include any material layer stack that is effective for the purpose of generating the high-frequency magnetic field for superposition with the recording magnetic field. The combination of the high-frequency magnetic field with the recording magnetic field lowers the coercivity of the magnetic medium on a disk during the recording process. 
     In an illustrative example shown in  FIG.  5 B , the spin torque oscillator  250  stack can include a stack, from the side of the leading edge to the side of the trailing edge, an electrically conductive, non-magnetic seed layer  252 , a spin polarized layer  256  that generates precession of magnetization during operation, a non-magnetic electrically conductive spacer layer  256 , and an optional magnetic field generating layer  258 . In an illustrative example, the non-magnetic conductive seed layer  252  can include a non-magnetic conductive material such as Cr, Ru, W, and Cu, the spin polarized layer can include a magnetic nickel-iron alloy, the non-magnetic conductive spacer layer  256  can include a non-magnetic conductive material such as Cu, and the optional field generating layer  258 , if present, can include another magnetic nickel-iron alloy. If the field generating layer  258  is present, then another optional non-magnetic, electrically conductive spacer layer (e.g., copper spacer layer) may be located between layer  258  and the trailing shield  280 . 
     The thickness of the non-magnetic conductive seed layer  252  can be in a range from 3 nm to 12 nm, although lesser and greater thicknesses can also be employed. The thickness of the spin polarized layer  256  can be in a range from 3 nm to 12 nm, although lesser and greater thicknesses can also be employed. The frequency of the magnetic field generated by the spin polarized layer  256  can be in a range from 10 GHz to 40 GHz, although lesser and greater frequencies can be employed. The magnitude of the magnetic field generated by the spin polarized layer  256  can be in a range from 250 Gauss to 1,000 Gauss, although lesser and greater magnitudes can be employed for the magnetic field. The thickness of the non-magnetic conductive spacer layer  256  may be in a range from 3 nm to 15 nm, although lesser and greater thicknesses can also be employed. The thickness of the field generating layer  258 , if present, may be in a range from 3 nm to 12 nm, although lesser and greater thicknesses can also be employed. Additional layers may be optionally employed to enhance performance of the spin torque oscillator  250  stack. 
       FIG.  6    shows magnified views of a second exemplary embodiment of a recording head  660  that includes a record element  200  according to a second embodiment of the present disclosure. The recording head  660  illustrated in  FIG.  6    can be derived from the recording head  660  illustrated in  FIGS.  5 A and  5 B  by modifying the record element  200 . 
     The recording head  660  of the second exemplary embodiment is the same as the recording head  660  of the first exemplary embodiment, except that the conductive layer stack  350  is replaced by a first conductive material portion  340 , and the dielectric spacer  310  may be omitted. All other components of the recording head  660  of the second exemplary embodiment are the same as those of the recording head  660  of the first exemplary embodiment and will not be repeated herein for brevity. 
     The first conductive material portion  340  is provided within the second electrically conductive path ECP 2 . The first conductive material portion  340  is not exposed to the ABS and is spaced from the ABS by the spin torque oscillator  250  stack and/or the throat portion of the trailing shield  280 . Preferably but not necessarily, the first conductive material portion  340  includes an electrically conductive non-magnetic metal (e.g., copper) or a non-magnetic metallic alloy. Alternatively, the first conductive material portion  340  can include a conductive multilayer stack of non-magnetic layers. In one embodiment, the first conductive material portion  340  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. 
     In one embodiment, the first conductive material portion  340  contacts the trailing sidewall of the main pole  220  and a rear sidewall of the spin torque oscillator  250  stack that is located on an opposite side of the STO  250  stack from the ABS. The second conductive material portion  360  can be located on a trailing sidewall of the first conductive material portion  340  and contact the trailing shield  280 . Thus, the first and the second conductive material portions  340 ,  360  electrically short the main pole  220  to the trailing shield  280 . In one embodiment, an interface between the spin torque oscillator  250  stack and the trailing shield  280  can be within the same plane as an interface between the first conductive material portion  340  and the second conductive material portion  360 . In one embodiment, the first conductive material portion  340  and the spin torque oscillator  250  stack can be located directly on the trailing sidewall of the main pole  220 . The STO  250  stack is located in the trailing gap  222  adjacent to the throat portion of the trailing shield  280 , while the first and the second conductive material portions  340 ,  360  are not exposed to the ABS and are located in the wider portion of the gap above the throat portion of the trailing shield  280 . 
     The electrical bias circuitry  290  is configured to flow electrical current between the first electrode (embodied as the main pole  220 ) and the second electrode (embodied as the trailing shield  280 /upper pole  285 ) through the first electrically conductive path ECP 1  and the second electrically conductive path ECP 2  in a forward direction and in a reverse direction depending on selection of a bias direction. The spin torque oscillator  250  stack can have the same configuration as, and provide the same function as, in the first embodiment. 
     In an alternative embodiment, first and the second conductive material portions  340 ,  360  may be replaced by single electrically conductive, non-magnetic layer, such as copper. Thus, a single electrically conductive, non-magnetic layer may be located in the trailing gap  222  in addition to the STO  250 . 
       FIGS.  7 A and  7 B  show magnified views of a third exemplary embodiment of a recording head  660  that includes a conductive material portion  360  as a read element according to a third embodiment of the present disclosure. The recording head  660  illustrated in  FIGS.  7 A and  7 B  can be derived from the recording head  660  illustrated in  FIGS.  5 A and  5 B  by modifying the record element  200 . 
     The recording head  660  of the third exemplary embodiment is the same as the recording head  660  of the first exemplary embodiment, except that the STO  250  and the conductive layer stack  350  are replaced by a conductive material portion  360 , and the dielectric spacer  310  may be omitted. All other components of the recording head  660  of the second exemplary embodiment are the same as those of the recording head  660  of the first exemplary embodiment and will not be repeated herein for brevity. 
     Preferably but not necessarily, the conductive material portion  360  includes at least one electrically conductive, non-magnetic material layer, such as at least one metal (e.g., copper, gold, platinum, ruthenium, chromium or tungsten) layer or a non-magnetic metallic alloy layer, such as a single electrically conductive non-magnetic material layer. Alternatively, the conductive material portion  360  can include a conductive multilayer stack of non-magnetic layers, or a multilayer stack of electrically conductive, magnetic and non-magnetic layers. In one embodiment, the conductive material portion  360  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. 
     The record element  200  can consist of only the conductive layer  360 , which is located on a trailing sidewall of the main pole  220 . Side magnetic shields  206  can be provided around the main pole  220  tip without physically contacting the main pole  220  as illustrated in  FIG.  7 B . The side magnetic shields  206  can be provided on the sides of the main pole  220 , and may contact the seed layer  207  and the trailing shield  280 . A gap  205  filled with a dielectric is provided between the main pole  220  and each of the seed layer  207  and the side magnetic shields  206 . The trailing shield  280  is a magnetic shield located on a trailing sidewall of the spin torque oscillator  250  stack. 
     The main pole  220  is configured to serve as a first electrode of an electrical circuit, and the trailing shield  280  is configured to serve as a second electrode of the electrical circuit. The electrical circuit is biased by the bias circuitry  290 , which is configured to provide electrical current through the main pole  220  and the trailing shield  280 /upper pole  285  in two opposite directions, which correspond to the two opposite magnetization directions that the record element  200  can induce in the magnetic medium to be recorded. An air bearing surface (ABS) of the magnetic head  600  includes planar surfaces of the main pole  220 , the conductive material portion (e.g., the non-magnetic conductive layer)  360 , and the trailing shield  280 . Thus, in this embodiment, the conductive material portion  360  is exposed to the ABS. The planar surfaces can be within a same two-dimensional plane that provided by lapping during a manufacturing process. In one embodiment, the conductive layer  360  located in the trailing gap  222  contacts the trailing sidewall of the main pole  220  and a leading sidewall of trailing shield  280  to electrically short them. 
     According to an aspect of the present disclosure, an electrically conductive path ECP is present through the conductive layer  360  between the first electrode (as embodied as the main pole  220 ) and the second electrode (as embodied as the trailing shield  280 ). The electrical bias circuitry  290  is configured to flow electrical current between the first electrode (embodied as the main pole  220 ) and the second electrode (embodied as the trailing shield  280 ) through the electrically conductive path ECP in a forward direction and in a reverse direction depending on selection of a bias direction. 
     In one embodiment, a distal end of the main pole  220  and a distal end of the trailing magnetic shield  280 , can be located on an opposite side of the air bearing surface ABS. The distal end of the main pole  220  which is connected to one electrical contact  291  can be an end portion of the first electrode the electrical bias circuitry  290 , and the distal end of the trailing shield  280  which is connected to another electrical contact  292  of the electrical bias circuitry  290  can be an end portion of the second electrode. The electrically conductive path ECP through the conductive layer  360  (i.e., through the record element  200  which consists of only layer  360 ) can be the only path that provides electrical conduction between the distal end of the main pole  220  and the distal end of the trailing magnetic shield  280  for conduction of electrical current through the main pole. In one embodiment, an electrically insulating material layer  272  can provide physical isolation and electrical isolation between the distal end of the main pole  220  and the distal end of the upper pole  285 . 
     The record element  200  of the first, second and/or third embodiments may be incorporated into the magnetic head  600  shown in  FIG.  4   . A magnetic storage device can be provided, which includes the magnetic head  600  incorporating the features of the first, second or third exemplary recording head  660 , the magnetic medium which may be embodied as the magnetic recording layer  710  of the recording track  840  of a disk medium  850 , a drive mechanism for passing the magnetic medium over the magnetic head  600 , and a controller electrically coupled to the magnetic head  600  for controlling operation of the magnetic head  600  as illustrated in  FIGS.  2  and  3   . 
       FIGS.  8 A- 8 F  illustrate a sequence of processing steps that can be employed to manufacture the first exemplary recording head. Referring to  FIG.  8 A , an auxiliary pole  202 , side magnetic shields  206 , and a dielectric material filling a portion of the gap  205  between the main pole  220  and the side magnetic shields  206  (not shown for clarity) are formed over a substrate  300 . The main pole  220  is subsequently formed within a groove formed in the dielectric material. In one embodiment, the main pole  220  may have a leading edge tapered surface  220 A (which may be supported by the side magnetic shield  206  and/or by a dielectric layer, which is not shown for clarity) and a trailing edge tapered surface  220 B. Subsequently, a layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) for forming a spin torque oscillator stack can be formed on a top (i.e., trailing) surface of the main pole  220 , which is a trailing sidewall of the main pole  220 . The layer stack may extend over the trailing edge tapered surface  220 B of the main pole (not shown for clarity). Specifically, the non-magnetic conductive seed layer  252 , the spin polarized layer  256  that generates precession of magnetization during operation, the non-magnetic conductive spacer layer  256 , and the optional field generating layer  258  can be sequentially deposited. The composition and the thickness of the various component layers ( 252 ,  254 ,  256 ,  258 ) for the spin torque oscillator  250  stack can be as described above. The various component layers ( 252 ,  254 ,  256 ,  258 ) can be formed by conformal and/or non-conformal deposition process such as chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), and/or various plating methods. 
     Referring to  FIG.  8 B , the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) for forming the spin torque oscillator stack can be patterned by a combination of a lithographic patterning process and an etch process. For example, a photoresist layer (not shown) can be applied over the spin torque oscillator  250  stack, and can be lithographically patterned to cover two discrete portions near an edge of the main pole  220  that is proximal to the air bearing surface to be subsequently formed. The gap between the two discrete portions of the patterned photoresist layer can have the dimension of the width of the dielectric spacer  310  to be subsequently formed, and may be in a range from 15 nm to 60 nm, although lesser and greater widths can also be employed. The pattern in the photoresist layer is transferred to through the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) by the etch process. For example, an ion milling process that employs the patterned photoresist layer as an etch mask can be employed to pattern the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ). 
     A continuous remaining portion of the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) located at the air bearing surface side constitutes the spin torque oscillator  250  stack, which is a mesa structure. Another continuous remaining portion of the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) located adjacent to the spin torque oscillator  250  stack constitutes the conductive layer stack  350 , which is another mesa structure. A trench  309  is provided between the spin torque oscillator  250  stack and the conductive layer stack  350 . A field region  269  is provided, which includes a physically exposed top surface of the main pole  220  and is free of remaining portions of the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ). The conductive layer stack  350  has a same set of component layers ( 252 ,  254 ,  256 ,  258 ) as the spin torque oscillator  250  stack. 
     Referring to  FIG.  8 C , a dielectric material can be deposited in the trench  309  and in the field region  269 . Excess portions of the dielectric material can be removed from above the top surfaces of the conductive layer stack  350  and the spin torque oscillator  250  stack by a planarization process such as chemical mechanical planarization (CMP). The remaining portion of the dielectric material in the trench  309  constitutes the dielectric spacer  310 . The remaining portion of the dielectric material in the field region  269  constitutes a first dielectric material portion  270 A. The dielectric spacer  310  and the first dielectric material portion  270 A include a dielectric material such as aluminum oxide, silicon oxide, or silicon nitride. The conductive layer stack  350  is spaced from the spin torque oscillator  250  stack by the dielectric spacer  310 . 
     Referring to  FIG.  8 D , another dielectric material can be deposited and patterned to form a second dielectric material portion  270 B, which can be formed directly on the top surface of the first dielectric material portion  270 A. The second dielectric material portion  270 B includes a dielectric material such as aluminum oxide, silicon oxide, or silicon nitride. The first and second dielectric material portions ( 270 A,  270 B) can be components of the insulating material portion  270 . An electrically conductive, non-magnetic material can be deposited over the top surface of the conductive layer stack  350 . For example, a lithographic patterning process can be performed to form a patterned photoresist layer including an opening within the area of the conductive layer stack  350 . The conductive material can be deposited in the opening in the photoresist layer, and the photoresist layer can be lifted off to form the conductive material portion  360  described above. Alternatively, a non-conductive material layer may be deposited as a continuous layer, and can be patterned by a combination of a lithographic patterning process and an etch (e.g., ion milling) process to provide the conductive material portion  360 . In this case, the second dielectric material portion  270 B can be formed before or after forming the conductive material portion  360 . In one embodiment, the conductive material portion  360  does not physically contact the spin torque oscillator  250  stack. 
     Preferably but not necessarily, the conductive material portion  360  includes a non-magnetic metal or a non-magnetic metallic alloy. Alternatively, the conductive material portion  360  can include a conductive multilayer stack of non-magnetic layers. In one embodiment, the conductive material portion  360  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. 
     In one embodiment, the conductive material portion  360  can have a homogeneous composition throughout. In one embodiment, the conductive material portion  360  can comprise, and/or consist essentially of, copper, tungsten, ruthenium, chromium, and/or any other non-magnetic metal or a non-magnetic metallic alloy. The thickness of the conductive material portion  360  can be in a range from 20 nm to 200 nm, although lesser and greater thicknesses can also be employed. The conductive material portion  360  is formed over the trailing sidewall of the main pole  220 , and directly on a trailing sidewall of the conductive layer stack  350 . 
     Referring to  FIG.  8 E , the trailing shield  280  (which is a magnetic shield located on the side of the trailing sidewall of the spin torque oscillator  250  stack) can be formed. The trailing shield  280  can be formed directly on the top surfaces (which are trailing sidewalls) of the conductive material portion  360  and the spin torque oscillator  250  stack by deposition and patterning of a soft magnetic material. Subsequently, additional material layer can be deposited and patterned as needed. For example, components of the magnetic coil  225 , additional portions of the insulating material portion  270  and the upper pole  285  can be formed and a recess in a trailing sidewall of the main pole can be formed by ion milling (not shown for clarity). 
     Referring to  FIG.  8 F , an air bearing surface (ABS) of the magnetic head  600  can be provided by lapping portions of the main pole  220 , the spin torque oscillator  250  stack, and the trailing shield  280 . As discussed above, the first electrically conductive path ECP 1  includes the spin torque oscillator  250  stack, and the second electrically conductive path ECP 2  includes the conductive layer stack  350  and the conductive material portion  360 . 
       FIGS.  9 A- 9 E  illustrate a sequence of processing steps that can be employed to manufacture the second exemplary recording head. Referring to  FIG.  9 A , an exemplary structure that can be employed to form the second exemplary recording head is shown, which can be the same as the exemplary structure shown in  FIG.  8 A . 
     Referring to  FIG.  9 B , the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) for forming the spin torque oscillator stack can be patterned by a combination of a lithographic patterning process and an etch process. For example, a photoresist layer (not shown) can be applied over the spin torque oscillator  250  stack, and can be lithographically patterned to cover a discrete portion near an edge of the main pole  220  that is proximal to the air bearing surface to be subsequently formed. The pattern in the photoresist layer is transferred to through the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) by the etch process. For example, an ion milling process that employs the patterned photoresist layer as an etch mask can be employed to pattern the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ). A continuous remaining portion of the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ) located at the air bearing surface side constitutes the spin torque oscillator  250  stack, which is a mesa structure. A field region  269  is provided, which includes a physically exposed top surface of the main pole  220  and is free of remaining portions of the layer stack of component layers ( 252 ,  254 ,  256 ,  258 ). 
     Referring to  FIG.  9 C , a first electrically conductive, non-magnetic material can be deposited over a physically exposed top surface of the main pole  220  adjacent to the spin torque oscillator  250  stack. For example, a lithographic patterning process can be performed to form a patterned photoresist layer including an opening adjacent to the spin torque oscillator  250  stack. The first conductive material can be deposited in the opening in the photoresist layer, and the photoresist layer can be lifted off. The remaining portion of the first conductive material constitutes a first conductive material portion  340 . Alternatively, the first conductive material layer may be deposited as a continuous layer, and can be patterned by a combination of a lithographic patterning process and an etch (e.g., ion milling) process to provide the first conductive material portion  340 . 
     Preferably, but not necessarily, the first conductive material portion  340  includes a non-magnetic metal or a non-magnetic metallic alloy. Alternatively, the first conductive material portion  340  can include a conductive multilayer stack of non-magnetic layers. In one embodiment, the first conductive material portion  340  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. In one embodiment, the first conductive material layer includes a non-magnetic conductive material such as copper, ruthenium, chromium, tungsten, another non-magnetic elemental metal, or a non-magnetic alloy thereof. 
     In one embodiment, the first conductive material portion  340  can contact a sidewall of the spin torque oscillator  250  stack. In one embodiment, the top surface of the first conductive material portion  340  may be planarized. In this case, the top surface of the first conductive material portion  340  can be coplanar with the top surface of the spin torque oscillator  250  stack. In one embodiment, the first conductive material portion  340  can comprise, and/or consist essentially of, copper, tungsten, ruthenium, chromium, and/or any other non-magnetic metal or a non-magnetic metallic alloy. The first conductive material portion  340  is formed directly on a trailing sidewall of the main pole  220 . 
     Referring to  FIG.  9 D , a dielectric material can be deposited in the region that is not covered by the spin torque oscillator  250  stack or the first conductive material portion  340 . The dielectric material can be deposited as a continuous material layer, and excess portions of the dielectric material can be removed from above the first conductive material portion  340  and the spin torque oscillator  250  stack by a masked etch process. The remaining portion of the dielectric material constitutes a dielectric material portion  270 C, which can be a portion of the insulating material portion  270 . 
     A second electrically conductive, non-magnetic material can be deposited on the first conductive material portion  340 . For example, a lithographic patterning process can be performed to form a patterned photoresist layer including an opening overlying the first conductive material portion  340 . The second conductive material can be deposited in the opening in the photoresist layer, and the photoresist layer can be lifted off. The remaining portion of the second conductive material constitutes a second conductive material portion  360 . Alternatively, the second conductive material layer may be deposited as a continuous layer, and can be patterned by a combination of a lithographic patterning process and an etch (e.g., ion milling) process to provide the second conductive material portion  360 . 
     Preferably but not necessarily, the second conductive material portion  360  includes a non-magnetic metal or a non-magnetic metallic alloy. Alternatively, the second conductive material portion  360  can include a conductive multilayer stack of non-magnetic layers, or a conductive multilayer stack of magnetic layers. In one embodiment, the second conductive material portion  360  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. In one embodiment, the second conductive material portion  360  includes a non-magnetic conductive material such as copper, ruthenium, chromium, tungsten, another non-magnetic elemental metal, or a non-magnetic alloy thereof. The second conductive material portion  360  can include the same material as, or a different material from, the first conductive material portion  340 . In one embodiment, the second conductive material portion  360  can have a homogeneous composition throughout. In one embodiment, the second conductive material portion  360  can comprise, and/or consist essentially of, copper, tungsten, ruthenium, chromium, and/or any other non-magnetic metal or a non-magnetic metallic alloy. The thickness of the second conductive material portion  360  can be in a range from 20 nm to 200 nm, although lesser and greater thicknesses can also be employed. The second conductive material portion  360  is formed over the main pole  220 , and directly on a trailing sidewall of the first non-magnetic conductive material portion  340 . 
     Referring to  FIG.  9 E , the trailing shield  280  (which is a magnetic shield located on the side of the trailing sidewall of the spin torque oscillator  250  stack) can be formed. The trailing shield  280  can be formed directly on the top surfaces (which are trailing sidewalls) of the conductive material portion  360  and the spin torque oscillator  250  stack by deposition and patterning of a soft magnetic material. Subsequently, additional material layers can be deposited and patterned as needed. For example, components of the magnetic coil  225 , additional portions of the insulating material portion  270  and the upper pole  285  can be formed and a recess in a trailing sidewall of the main pole can be formed by ion milling (not shown for clarity). 
     An air bearing surface (ABS) of the magnetic head  600  can be provided by lapping portions of the main pole  220 , the spin torque oscillator  250  stack, and the trailing shield  280 . As discussed above, the first electrically conductive path ECP 1  includes the spin torque oscillator  250  stack, and the second electrically conductive path ECP 2  includes the first and second conductive material portions ( 340 ,  360 ). 
       FIGS.  10 A- 10 C  illustrate a sequence of processing steps that can be employed to manufacture the third exemplary recording head. Referring to  FIG.  10 A , an auxiliary pole  202 , side magnetic shields  206 , and a dielectric material filling a portion of the gap  205  between the main pole  220  and the auxiliary pole  202  and the side magnetic shields  206  are formed over a substrate (not shown). The main pole  220  is subsequently formed within a groove formed in the dielectric material. 
     Subsequently, an electrically conductive, non-magnetic material can be deposited on the air bearing side of the top surface of the main pole  220 . For example, the conductive material layer may be deposited as a continuous layer, and can be patterned by a combination of a lithographic patterning process and an etch (e.g., ion milling) process to provide a conductive material portion  360 . Alternatively, the conductive material portion  360  can be formed by a lift-off process. Preferably but not necessarily, the conductive material portion  360  includes a non-magnetic metal or a non-magnetic metallic alloy. Alternatively, the conductive material portion  360  can include a conductive multilayer stack of non-magnetic layers, or a conductive multilayer stack of magnetic layers. In one embodiment, the conductive material portion  360  does not include a material that generates an alternating magnetic field upon application of an electrical current therethrough. In one embodiment, the conductive material portion  360  includes a non-magnetic conductive material such as copper, gold, platinum, ruthenium, chromium, tungsten, another non-magnetic elemental metal, or a non-magnetic alloy thereof. In one embodiment, the conductive material portion  360  can comprise, and/or consist essentially of, copper, gold, platinum, tungsten, ruthenium, chromium, and/or any other non-magnetic metal or a non-magnetic metallic alloy. The conductive material portion  360  is formed directly on a trailing sidewall of the main pole  220 . 
     Referring to  FIG.  10 B , a dielectric material can be deposited in the region that does not overlap with the conductive material portion  360 . The dielectric material can be deposited as a continuous material layer, and excess portions of the dielectric material can be removed from above the conductive material portion  360  by a masked etch process. Alternatively, a patterned mask layer including an opening adjacent to the conductive material portion  360  can be formed. A dielectric material can be deposited within the opening, and the patterned mask layer can be lifted off. The remaining portion of the dielectric material constitutes a dielectric material portion  270 D, which can be a portion of the insulating material portion  270 . The dielectric material portion  270 D includes a dielectric material such as aluminum oxide, silicon oxide, or silicon nitride. 
     Referring to  FIG.  10 C , the trailing shield  280  (which is a magnetic shield located on the side of the trailing sidewall of the spin torque oscillator  250  stack) can be formed. The trailing shield  280  can be formed directly on the top surface (which is the trailing sidewall) of the conductive material portion  360  by deposition and patterning of a soft magnetic material. Subsequently, additional material layers can be deposited and patterned as needed. For example, components of the magnetic coil  225 , additional portions of the insulating material portion  270  and the upper pole  285  can be formed and a recess in a trailing sidewall of the main pole can be formed by ion milling (not shown for clarity). 
     An air bearing surface (ABS) of the magnetic head  600  can be provided by lapping portions of the main pole  220 , the conductive material portion  360 , and the magnetic shield (i.e., the trailing shield  280 ). As discussed above, the electrically conductive path ECP includes the magnetic conductive material portion  360 . 
     The various recording heads of the present disclosure provide advantages over prior art recording heads by utilizing Ampere&#39;s field generated by electrical current through a conductive material portion  360 . Specifically, the electrical current flowing between the main pole  220  and the trailing shield  280  generates the Ampere&#39;s field, which is employed to achieve significant areal density capability (ADC) gain. The areal density capability from the Ampere&#39;s field can be significant. 
       FIG.  11    shows magnetization M, bias current I, and the current induced Ampere&#39;s field in the main pole  220  and in the trailing shield  280  in the vicinity of a trailing gap  222 , which includes the record element  200  containing the conductive material portion  360 , for the third exemplary recording head. The principle of operation illustrated in  FIG.  11    applies equally to the second electrically conductive path ECP 2  of the first and second exemplary recording heads. 
     Referring back to  FIGS.  5 A,  5 B,  6 ,  7 A, and  7 B , the main pole  220  and the trailing magnetic shield  280  can be in direct electric contact through the conducting trailing gap  222  containing the record element  200 , which can consist of the conductive material portion  360  as in the third embodiment, or can include the conductive material portion  360  and the spin torque oscillator  250  stack and additional components as in the first and second embodiments. The main pole  220  and the trailing shield  280  are otherwise electrically insulated and isolated from each other. The main pole  220  constitutes a first electrode and the trailing shield  280 /upper pole  285  constitutes a second electrode. When an electrical bias voltage is applied across the first and second electrodes, electrical current flows from the main pole  220  into the trailing shield  280 , or vice versa through the record element  200 . 
     In one embodiment, the insulating material layer  272  can be a thin dielectric layer such as an aluminum oxide layer, which is provided in the back gap area between end portions of the first electrode and the second electrode. The insulating material layer  272  can have a thickness in a range from 10 nm to 100 nm, such as from 20 nm to 50 nm, although lesser and greater thicknesses can also be employed. Additional insulating material can be provided in order to provide electrical isolation between the first electrode (as embodied as the main pole  220 ) and the second electrode (as embodied as the trailing shield  280 ). 
     During operation of the recording heads of the present disclosure, an electrical bias voltage is applied across the main pole  220  and the trailing shield  280 . The electrical bias voltage induces electrical current between the main pole  220  and the trailing shield  280 . This electrical current improves performance of the recording head with a higher ADC, as elaborated below. The electrical bias voltage across the main pole  220  and the trailing shield  280  can be a direct current (DC) bias voltage (with either polarity), or can be an alternating current (AC) bias voltage. In the case of an AC bias voltage, it is preferred to have a waveform that follows the waveform of the write current through the magnetic coil  225  per the bits to be written, either in-phase, or out of phase. In other words, an AC bias voltage can be applied as a pulse only during the transition in the magnetization during the recording process. 
     During operation of the recording heads of the present disclosure, an electric current flows from the main pole  220  into the trailing shield  280 , or vice versa. As illustrated in  FIG.  12   , this current produces an Ampere field inside both the main pole  220  and the trailing shield  280 , as well as in the recording media.  FIG.  12    shows finite element model (FEM) simulation results of the bias current distribution and the Ampere&#39;s field (MP) produced by 5 mA of the bias current through the main pole according to an embodiment of the present disclosure. For a bias current of 5 mA (which corresponds to a bias voltage of 150 mV and a total resistance of 30 Ohm), a circular field inside the main pole  220  is clearly visible, with magnitude of ˜100 Oe at the ABS side, and ˜200 Oe in the back, which is consistent with the current density distribution (higher in the back and lower at the ABS). 
     Because of the small dimension defined by the bump position, the high current density is mainly concentrated inside the main pole  220  and the trailing shield  280  in the vicinity of the trailing gap  222  area, which is in the range of approximately from 100 nm to 150 nm into the air bearing surface (ABS). According to Ampere&#39;s law, this current will produce a circular magnetic field that is in the direction transverse to that of the current. Since the current direction is substantially the same as the direction of the magnetization of the main pole  220  and the trailing shield  280 , this Ampere field is also transverse to the magnetization, thus producing a transverse magnetization component with respect to the flux flow direction in the main pole  220  and the trailing shield  280  around the trailing gap  222 . This will in turn make faster the flux reversal in the main pole  220  and trailing shield  280 . 
     In addition to the current induced Ampere field inside the recording head that makes the magnetization switching faster, the Ampere field also has other non-limiting benefits. One benefit is that the Ampere field could change the magnetization direction of the main pole and the trailing shield in the vicinity of the trailing gap, such that the flux shunt from the main pole  220  into the trailing shield  280  is reduced, leading to higher field (thus higher overwrite) in the media. Another benefit is that the media will also experience this Ampere&#39;s field. 
     Although the foregoing refers to particular preferred embodiments, it will be understood that the disclosure is not so limited. It will occur to those of ordinary skill in the art that various modifications may be made to the disclosed embodiments and that such modifications are intended to be within the scope of the disclosure. Where an embodiment employing a particular structure and/or configuration is illustrated in the present disclosure, it is understood that the present disclosure may be practiced with any other compatible structures and/or configurations that are functionally equivalent provided that such substitutions are not explicitly forbidden or otherwise known to be impossible to one of ordinary skill in the art. All of the publications, patent applications and patents cited herein are incorporated herein by reference in their entirety.