Abstract:
Perpendicular recording and magnetoresistive sensing transducers are disclosed having additional coil windings carrying current in an opposite direction to windings encircled by a core. The magnetic influence of the recording transducer on the sense transducer is reduced or eliminated. The inductance of the coils used to drive the recording transducer is reduced, facilitating high-frequency operation. Moreover, the magnetic flux induced by the coils and transmitted by the recording pole tip is increased, improving recording capabilities.

Description:
BACKGROUND 
     The present invention relates to electromagnetic transducers for information storage and retrieval systems, such as disk or tape drives. 
     Current commercially available disk drives employ magnetoresistive (MR) sensors for reading data, and store data in domains having magnetizations that are substantially parallel to concentric media tracks, the parallel magnetic storage sometimes called longitudinal recording. It has been predicted that such longitudinal magnetic storage will become unstable at normal operating conditions when the domains reach a minimal size, termed the superparamagnetic limit. In order to store the data at higher density, the drive system may instead be designed to store data in domains that are substantially perpendicular to the disk surface, which may be termed perpendicular recording. 
     Prior art systems for perpendicular recording include an inductive transducer positioned in close proximity to a surface of a disk. The inductive transducer has a U-shaped core formed of high-permeability, low-coercivity or “soft” magnetic material and the media has a soft magnetic underlayer, the core and underlayer forming a magnetic circuit that traverses a higher coercivity media layer, for magnetizing the media layer or reading the magnetization of the media layer. The core has magnetic pole tips that differ in area so that the magnetic signal is concentrated in the smaller pole tip for reading or writing data. The pole tips are sufficiently separated to encourage magnetic flux to travel through the media, instead of across a submicron nonmagnetic gap that is typically employed for longitudinal recording. 
     MR sensors sense a change in magnetic field at the sensor with a change in resistance of the sensor, which may be measured as a change in current or voltage across the sensor. In an attempt to limit the sensing of a MR sensor to the individual bit directly adjacent the sensor, magnetic shields are disposed in the transducer adjacent the sense element, shielding the sense element from the magnetic fields emanating from adjacent bits. 
     The present inventors have discovered, however, that the shields can form a magnetic circuit with the media underlayer used in perpendicular recording, causing problems in reading and writing. Moreover, the relatively large distance between the trailing perpendicular recording pole tip and a MR sensor disposed on an opposite side of the flux return pole tip can cause misalignment of the MR sensor and the recording pole tip. In addition, increasing the density of bits on each track and the disk speed requires higher frequency recording, for which inductance of the coils and core may become problematic. 
     SUMMARY 
     In accordance with the present invention, embodiments of a merged perpendicular recording and magnetoresistive sensing transducer are disclosed in which the magnetic influence of the recording transducer on the sense transducer and the shields is reduced. As one example, the magnetic flux produced by the recording coil may be essentially zero at the sense transducer. Another advantage of the invention is that the inductance of the coils used to generate magnetic flux in the recording transducer is reduced, facilitating high-frequency operation. Moreover, the magnetic flux generated by the core and transmitted by the recording pole tip may be increased, improving recording capabilities. In brief, various embodiments of a merged transducer are disclosed having increased recording flux, reduced inductance and reduced influence of the recording elements on the sensing elements, for greatly improved performance. 
    
    
     BRIEF DESCRIPTION OF THE FIGURES 
     FIG. 1 is a cutaway cross-sectional view of a portion of an information storage system including a merged perpendicular recording and magnetoresistive sensing transducer disposed adjacent to a spinning disk, with a pair of coil layers carrying current in opposite directions. 
     FIG. 2 is a cutaway cross-sectional view of a merged perpendicular recording and magnetoresistive sensing transducer with a solenoidal configuration that encircles one of the pole layers of the transducer. 
     FIG. 3 is a cutaway cross-sectional view of the transducer of FIG. 1 showing various distances and dimensions. 
     FIG. 4 is a plot of the inductance of the coil layers and the magnetic field strength at the sensor while varying the number of windings in one of the coil layers. 
     FIG. 5 is a plot of the write field and the write field gradient at the media layer adjacent the recording pole tip while varying the number of windings in one of the coil layers. 
     FIG. 6 is a plot of the write field at the media layer adjacent the recording pole tip and the magnetic field strength at the sensor while varying the distance of one coil layer from the media-facing surface. 
     FIG. 7 is a plot of the write field at the media layer adjacent the recording pole tip and the magnetic field strength at the sensor while varying the length of a shield layer from the media-facing surface. 
     FIG. 8 is a perspective view of a pair of interconnected spiral coil layers sandwiching a recording pole layer. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 depicts a cutaway cross-sectional view of a portion of an information storage system  20  including a merged perpendicular recording and magnetoresistive sensing transducer  22  disposed adjacent to a media such as a spinning disk  25 . The transducer  22  is formed in a plurality of adjoining solid layers on a wafer substrate  28  that may remain affixed to the transducer  22 . A media-facing surface  33  of the solid body that includes the transducer  22  may be formed with a desired relief for fluid and solid interaction with the disk  25 , and the body may be termed a head or slider. 
     The disk  25  may be conventional and includes a self-supporting substrate  35 , a low-coercivity, high-permeability or “soft” magnetic underlayer  34 , a media layer  37  and a protective overcoat  39 . The disk  25  is spinning in a direction indicated by arrow  31  and has a surface  32  adjacent the media-facing surface  33  of the head. 
     Atop the slider substrate  28  a first soft magnetic shield layer  30  has been formed, for example of permalloy (Ni 0.8 Fe 0.2 ) either directly or atop an undercoat layer, not shown. A first layer of nonmagnetic, electrically insulating material has been formed on the shield layer, followed by a magnetoresistive (MR) sensor  44 . The MR sensor can be any sensor that utilizes a change in resistance caused by a change in magnetic field to sense that field, which may be measured as a change in current or voltage across the sensor, including anisotropic magnetoresistive (AMR) sensors, spin-valve (SV) sensors, spin-tunneling (ST) sensors, giant magnetoresistive (GMR) sensors and colossal magnetoresistive (CMR) sensors. A second layer of nonmagnetic, electrically insulating material has been formed between the MR sensor and a second soft magnetic shield layer  46 . The first and second layers of nonmagnetic, electrically insulating material, as well as additional layers of such material, are indicated together as region  40 . The MR sensor  44  may be electrically connected to the shield layers  30  and  46  in some embodiments, such as spin-tunneling sensors. 
     A first electrically conductive coil layer  55  is separated from second shield layer  46  by another nonmagnetic, electrically insulating layer, and is isolated from a first soft magnetic pole layer  58  by additional nonmagnetic, electrically insulating material. First pole layer  58  terminates adjacent the media-facing surface in a first pole tip  60  that faces the media  25 . A soft magnetic stud  62  connects the first pole layer  58  with a second soft magnetic pole layer  64 . Second pole layer  64  terminates adjacent the media-facing surface in a second pole tip  68  that faces the media  25 . Second pole layer  64  is thicker than the first pole layer  58  and serves as a flux return pole, and first pole tip  60  has a much smaller media-facing area than second pole tip  68 . In an alternative embodiment, the first pole layer  58  is thicker than the second pole layer  64  and serves as a flux return pole, and the second pole tip  68  has a much smaller media-facing area than first pole tip  60 . 
     A second electrically conductive coil layer  66  is partly disposed between first pole layer  58  and second pole layer  64  for driving the magnetic circuit. Coil layer  66  has a first plurality of winding sections  75  that are all directed in substantially the same direction in a region encircled by a magnetic circuit  72  formed by first pole layer  58 , stud  62 , second pole layer  64  and underlayer  34 . With the electrical current directed into the page as indicated by the crosses in winding sections  75 , magnetic flux  70  is directed as shown, with each of the pole layers contributing magnetic flux in the same (clockwise) direction of the circuit  72 . Since magnetic flux  70  travelling through magnetic circuit  72  is concentrated at first pole tip  60 , that pole tip  60  provides a stronger magnetic field to the media  25  and is used to write information such as data to the media. 
     A second plurality of winding sections  77  is disposed between pole layer  58  and shield  46  and carries current in an opposite direction from winding sections  75 , as indicated by the points in winding sections  77  representing current directed out of the page. Magnetic flux induced by winding sections  77  is directed toward media  25  in both pole layer  58  and pole layer  64 , those fluxes opposing each other so that winding sections  77  contribute less overall magnetic flux to the magnetic circuit  72  than that contributed by winding sections  75 . 
     Winding sections  77  counteract the magnetic flux induced by winding sections  75  in shield  30 , shield  40  and MR sensor  44 , reducing destabilizing effects of the perpendicular write transducer on the MR sensor. As described below, the induced flux from coil layer  55  can be configured to essentially completely cancel the magnetomotive force induced by coil layer  66  at the MR sensor  44 , substantially eliminating the effect of those coil layers on the MR sensor. 
     Moreover, additional winding sections  80  of coil layer  55  carry current in an opposite direction from additional winding sections  82  of coil layer  66 , so that the inductance of those sections is substantially canceled by each other. Similarly, the inductance of winding sections  75  is substantially canceled by the inductance of winding sections  77 . Thus the overall inductance of coil layers  55  and  66  is substantially less than that of either layer  55  or layer  66  alone, significantly increasing the frequency at which data can be written, thereby providing increased storage density and, for disks that spin at a substantially constant speed, increased data access rates. 
     The coil layers  55  and  66  can be substantially identical spirals that are interconnected at the innermost section of each spiral, with an outermost section of each spiral connected to receive current from electronics of the information storage system. Thus a current spiraling inward along coil layer  55  spirals outward along coil layer  66 , with the direction of the current opposite for the two layers. Alternatively, the coil layers  55  and  66  may be identical spirals that are connected to drive electronics in the middle and connected to each other at an outermost section. Moreover, although a plurality of coil sections  75  and  77  are shown, a single coil section  75  and a single coil section  77  may suffice. 
     Alternatively, as shown in FIG. 2, a conductive coil can be connected in a solenoidal configuration that encircles one of the pole layers of transducer  82 . In order to illustrate differences of this approach, FIG. 2 is similar to FIG. 1, except for coil layers  85  and  88  and MR sensor  94 . In the embodiment shown in FIG. 2, coil layers  85  and  88  do not have sections that wind in a spiral in each respective layer. Instead, layer  85  has a plurality of winding sections  86 , and layer  88  has a plurality of winding sections  89 , with each winding section  86  connected to a winding section  89 . 
     In the embodiment of FIG. 2, a spin-tunneling sensor  94  is shown connected to the shield layers  30  and  46 , which also serve as or include conductive leads for the sensor  94 . Electrical current in sensor  94  is directed perpendicular to the plane of the sensor  94  layers, versus an in-plane direction of current for sensor  44 . The electrical connection between the shields  30  and  46  and the sensor  94  can make stray magnetic flux in the shields even more problematic for the spin-tunneling sensor  94  than for other sensors such as sensor  44 . 
     While FIG. 1 shows a current in-plane sensor  44  combined with a pair of spiral coil layers  55  and  66 , and FIG. 2 shows a current perpendicular-to-plane sensor  94  combined with solenoidal configuration of coil layers  85  and  88 , converse combinations are possible. Moreover, although FIG.  1  and FIG. 2 show the recording pole tip  60  closer than the return flux pole tip  68  to the MR sensor  44 , the reverse configuration is also possible. It is also possible for an electromagnetic sensor such as a MR or optical sensor to be located closer than the recording transducer to a trailing edge  90  of the head. 
     To facilitate discussion of additional inventive features, FIG. 3 labels the transducer  22  of FIG. 1 with dimensions for various elements, as shown in X and Y directions. The Y direction is away from the media and substantially perpendicular to the media-facing surface  33 . The X direction is orthogonal to the Y direction and oriented substantially along a line between a center of the MR sensor  44  and a center of the recording pole tip  60 . The X direction is thus oriented substantially along a track that is closest to sensor  44  and pole tip  60 , neglecting skew. The Z direction is into the drawing page, away from the viewer. 
     Y dimensions for elements are measured from the media-facing surface  33 , although a thin protective coating  98  (e.g., less than 10 nm of DLC) may isolate magnetically active elements from the media-facing surface  33 . Thus D1 is the distance of first coil layer  55  from the media-facing surface  33 , and D2 is the distance of second coil layer  66  from the media-facing surface  33 . Similarly, S1L is a length of first shield  30  measured from the media-facing surface  33 , and S2L is a length of second shield  46  measured from the media-facing surface  33 . T1 through T7 are the thicknesses of various layers of active elements. That is, T1 is the thickness of the first shield  30 , T2 is the thickness of the second shield  46 , T3 is the thickness of the first coil layer  55 , T4 is the thickness of the second coil layer  66 , T5 is the thickness of the first pole layer  58 , T6 is the thickness of the stud  62  and T7 is the thickness of the second pole layer  64 . N1 is the number of turns in first coil layer  55 , and N2 is the number of turns in second coil layer  66 . 
     FIG. 4 shows some effects of varying the number of winding sections N1 of auxiliary coil layer  55  while holding other elements constant. FIG. 4 plots the inductance L of the coil layers  55  and  66 , and the magnetic field strength in the Y direction (H y ) at the sensor  44  caused by coil layers  55  and  66 , for the case in which second coil layer  66  has nine turns (N2=9) and first coil layer  55  varies between zero and nine turns (0≧N1≧9). The inductance L is shown in nano-Henries (nH) as a solid line  101  and magnetic field H y  is shown in Oersted (Oe) as a broken line  103  in FIG.  4 . 
     The conventional situation in which coil layer  55  does not exist is shown as zero turns (N1=0), for which the magnetic field H y  at the sensor is nearly one-thousand Oe and the inductance L of coil layer  66  is nearly twenty-five nH. Improvement in both measures can be seen with the provision of additional coil turns in coil layer  55  up to the case in which coil layer  55  also has nine turns (N1=9), for which the magnetic field H y  at the sensor has dropped to nearly zero (about one) Oe and the inductance L of coil layer  66  is about seven nH. FIG. 4 provides a graphic illustration of the reduction in inductance and substantial cancellation of stray recording field at the sensor with the addition of a matching auxiliary coil layer  55  carrying current opposite to that of the coil layer  66  disposed between the pole layers  58  and  64 . 
     FIG. 5 shows other performance parameters for a transducer similar to that shown in FIG.  3  and for which second coil layer  66  has nine turns (N2=9) and first coil layer  55  varies between zero and nine turns (0≧N1≧9). The write field H y  at the media layer  37  adjacent recording pole tip  60  is shown in Oersted (Oe) as a solid line  105  and the write field gradient dH y /dx at that location is shown in Oersted/micron (oe/μm) as a broken line  107 . The conventional situation in which coil layer  55  does not exist is shown as zero turns (N1=0), for which the magnetic field H y  at the media layer  37  is about six-thousand one-hundred Oe and the write field gradient dH y /dx is less than thirty-eight-thousand Oe/μm. Improvement in both write field H y  and write field gradient dH y /dx can be seen with the provision of additional coil turns in coil layer  55  up to the case in which coil layer  55  also has nine turns (N1=9), for which the magnetic field H y  at the sensor has increased to about eight-thousand one-hundred Oe and the write field gradient dH y /dx is about than fifty-four-thousand Oe/μm. FIG. 5 thus provides a graphic illustration of the increase in recording field H y  and recording field gradient dH y /dx at the media layer  37  with the addition of a matching auxiliary coil layer  55  carrying current opposite to that of the coil layer  66  disposed between the pole layers  58  and  64 . 
     FIG. 6 shows some effects of varying the distance D1 of auxiliary coil layer  55  from the media-facing surface  33  while D2 is held fixed at six microns and both coils have six turns (N1=N2=6). On the left side of FIG. 6 is the magnetic field H y  at the sensor  44  from the coil layers  55  and  66 , which is plotted versus D1 as a solid line  109 . On the right side of FIG. 6 is the magnetic field H y  at the media adjacent the recording pole tip  60 , which is plotted versus D1 as a broken line  111 . The stray field H y  at the sensor  44  is approximately zero for D1 equal to two microns. Surprisingly, the stray field H y  at the sensor  44  increases as D1 increases to six microns, at which D1=D2. The magnetic field H y  at the media adjacent the recording pole tip  60  is about 8600 Oe for D1 equal to two microns, and decreases to about 8175 D1 equal to six microns. In other words, for this embodiment the stray field at the sensor can be cancelled and the write field improved by positioning the auxiliary coil layer  55  closer than the main coil layer  66  to the media-facing surface  33 . Although the invention is not to be limited to any particular theory, a reason for this effect may be the more efficient coupling of main coil layer  66  than auxiliary coil layer  55  to magnetic circuit  72 , so that auxiliary coil layer  55  in this example is closer than the main coil layer  66  to the sensor  44  in both the X and Y directions. 
     FIG. 7 shows some effects of varying the length S2L of second shield layer  46  from the media-facing surface  33  while other elements are unchanged. In this example, D1 is fixed at six microns, D2 is fixed at four microns and both coils have six turns (N1=N2=6) . First pole layer  58  has a length in this example of twenty-nine microns. The length S1L of first shield layer  30  does not have a substantial effect on performance provided that it is in a range between about ten microns and one hundred microns. The stray field H y  at the sensor  44  is listed on the left side of FIG.  7  and plotted versus S2L as a solid line  113 . The recording field H y  at the media layer adjacent pole tip  60  is listed on the right side of FIG.  7  and plotted versus S2L as a broken line  115 . The stray field H y  at the sensor  44  is zero when the length S2L of the second shield layer  46  about twelve microns in this example. 
     The length S2L of the second shield layer  46  will influence the amount of flux coupled to the sensor from the first coil  55  since it comprises part of the magnetic circuit of first coil  55 . The length of S2L will also influence the amount of flux coupled to the sensor from the second coil  66 . That is, the second shield  46  is also part of the magnetic circuit of the second coil  66 . The sensitivity of flux coupling with S2L length is different for each of the coils  55  and  66  and the signs of the respective fluxes are opposite. Thus when S2L is very small, first coil  55  dominates and a large positive flux is coupled to the sensor. When S2L is large, second coil  66  dominates and a large negative flux is coupled to the sensor. In example of FIG. 7, at S2L equal to about 12 microns the two fluxes cancel leaving the sensor unaffected by the write current. 
     The recording field H y  at the media layer adjacent pole tip  60  is slightly reduced S2L=12 μm compared to S2L=30 μm, at about 8596 Oe compared to about 8609 Oe, respectively. Thus it is advantageous for S2L to be less than the length of first pole layer  58  in this example. 
     Referring again to FIG. 3, a method for making the transducer  22  in accordance with the present invention is described. The transducer  22  is formed along with thousands of similar transducers, not shown, on the wafer substrate  28 , which may be made of AlTiC, Alumina, SiC or other known materials. Atop the wafer substrate  28  the first soft magnetic shield layer  30  is formed, for example by window frame plating, either directly on the substrate or atop a seed layer, not shown. First shield layer  30  may have a thickness T1 after lapping of about two μm, a height S1L of about thirty μm and a width of about ten μm, for example. 
     An alumina or other dielectric layer is then deposited and lapped to form a coplanar surface with the first shield layer  30 . A first submicron read gap layer of nonmagnetic, electrically insulating material is formed on the shield layer, followed by a magnetoresistive (MR) sensor  44 . A second submicron read gap layer of nonmagnetic, electrically insulating material is then formed between the MR sensor and the second soft magnetic shield layer  46 . The first and second layers of nonmagnetic, electrically insulating material, as well as additional layers of such material, are indicated together as region  40 . The MR sensor  44  may be electrically connected to the shield layers  30  and  46  in some embodiments, such as spin-tunneling sensors. 
     The second shield layer  46  is formed, for example by window frame plating, to a thickness T2 after lapping of about two μm and a width of about ten μm, for example. As noted above, the height S2L of second shield layer  46  is a controlled parameter in obtaining zero stray field at the MR sensor  44 , and may be about equal to that of the pole layers  58  and  64 , or about twelve μm in this embodiment. Since other factors may be employed to obtain zero stray field at the MR sensor  44 , the height of the second shield layer may be in a range between about five μm and one hundred μm. 
     After lapping the second shield layer  46  another dielectric layer is formed to a thickness that may preferably be between less than one μm and several μm, upon which the first electrically conductive coil layer  55  is formed, for example by frame plating. First coil layer  55  may be formed of copper, gold, silver or other electrically conductive materials, and is shown in perspective view in FIG.  8 . First coil layer  55  is formed in a spiral formation with winding sections  77  substantially parallel to the media-facing surface  33  in a region adjacent to second shield  46 . First coil layer  55  may have thickness T3 on the order of one μm, and winding sections  77  have a square cross-section about 1.5 μm on each side in one embodiment, with a distance between winding sections  77  about one μm. As noted above, the distance D1 of first coil layer  55  from the media-facing surface  33  is a controlled parameter in obtaining zero stray field at the MR sensor  44 , and may be less than that the distance D2 of second coil layer  66  from the media-facing surface, or about four microns in this embodiment. Since other factors may be employed to obtain zero stray field at the MR sensor  44 , distance D1 may be in a range between about one μm and ten μm, and may be equal to, greater than or less than the distance D2. 
     After polishing the first coil layer  55  a first portion of an electrically conductive interconnect  120  shown in FIG. 8 is formed, upon which another dielectric layer is formed to a thickness that may preferably be between less than one μm and several μm, after lapping that exposes the interconnect portion. The first soft magnetic pole layer  58  is then formed along with another portion of the electrically conductive interconnect  120 , for example by separate frame plating steps. The first pole layer  58  has a thickness T5 after lapping that may be less than one micron, e.g., 0.3 μm and a height of about ten to fifteen microns, for example. The first pole layer  58  has a tapered width that funnels magnetic flux through the pole tip  60 , the width ranging from about ten microns distal to the media-facing surface  33  to lees than one micron, e.g., 0.3 μm at the pole tip  60 , so that the pole tip has a media-facing area preferably about 0.1 μm 2  or less. 
     The soft magnetic stud  62  is formed to a thickness T6 of between about two and ten microns by techniques such as window frame plating in plural layers to connect the first pole layer  58  with the second pole layer  64 . After polishing the first pole layer  58  a first layer of the stud is formed along with another portion of the electrically conductive interconnect  120 , for example by separate frame plating steps. Another dielectric layer is formed to a thickness that may preferably be between less than one μm and several μm after lapping of it, the interconnect portion and the stud layer. 
     The second electrically conductive coil layer  66  is then formed, for example by frame plating of copper, gold, silver or other electrically conductive materials. Second coil layer  66 , shown additionally in FIG. 8, is formed in a spiral formation with winding sections  75  substantially parallel to the media-facing surface  33  in a region adjacent to first pole layer  58 . A central winding section  82  is connected with interconnect  120 . Second coil layer  66  may have thickness T4 on the order of one μm, and winding sections  75  have a square cross-section about 1.5 μm on each side in one embodiment, with a distance between winding sections  75  about one μm. Second coil layer  66  may be substantially identical to first coil layer  55  but may differ in distance D2 from the media-facing surface. Alternatively, second coil layer  66  may differ from first coil layer  55  in many ways to enhance the performance of transducer  22 . 
     After polishing the second coil layer  66  a final portion of the soft magnetic stud  62  is formed, upon which another dielectric layer is formed to a thickness that may preferably be between less than one μm and several μm, after lapping that exposes the stud portion. Second pole layer  64  is then formed, for example by frame plating, to a thickness between less than one and several microns, e.g., 1.5 μm, a height that preferably matches the first pole layer  58  and a width that may be tens of microns. Second pole layer  64  terminates adjacent the media-facing surface in a second pole tip  68  that faces the media  25 , second pole tip  68  having a media-facing surface at least an order of magnitude larger than that of first pole tip  60 . For example, second pole tip  68  may have a media-facing area that is greater than 10 μm 2 , so that second pole tip may have a media-facing area that is between 100 and 100,000 times as large as that of first pole tip  60 . In an alternative embodiment, the first pole layer  58  is thicker than the second pole layer  64  and serves as a flux return pole, and the second pole tip  68  has a much smaller media-facing area than first pole tip  60 . 
     A protective coating  96  of dielectric material such as alumina is formed on the second pole layer  64 , which will become the trailing end of the transducer  22 . Electrical connections  122  and  125 , shown in FIG. 8, extend from coil layers  55  and  66 , respectively, to provide electrical contacts either on the trailing end  90  or on a back surface of the head disposed opposite to the media-facing surface  33 . Similar electrical leads, not shown, extend from the MR sensor  44  to provide additional electrical contacts either on the trailing end  90  or the back surface. 
     After forming the protective coating  96  on the trailing end  90 , the wafer  28  is diced to form rows of heads, as is known in the art, and the media-facing surface is formed. The protective coating  98  of hard dielectric material such as diamond-like carbon (DLC), tetrahedral amorphous carbon (ta-C), silicon carbide (SiC) or the like is formed. The rows are then divided into individual heads that are attached to suspensions for positioning adjacent disks such as disk  25  in drive system  20 . 
     FIG. 8 shows a perspective view of the spiral coil layer  55  and spiral coil layer  66  interconnected at interconnect  120 . Electrical connections  122  and  125  provide current for the coil layers  55  and  66 . Tapered first pole layer  48  and pole tip  60  are shown but, for clarity, stud  62  and second pole layer  64  are not. 
     Although we have focused on teaching the preferred embodiments of an improved electromagnetic transducer, other embodiments and modifications of this invention will be apparent to persons of ordinary skill in the art in view of these teachings. Therefore, this invention is limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings.