Abstract:
A magnetic read head comprises a magnetic sensor mounted on a back surface of a slider, wherein the magnetic sensor includes a nonmagnetic member, a conductive shunt positioned adjacent to the nonmagnetic member, a first conductor electrically connected to the nonmagnetic member, and a second conductor electrically connected to the nonmagnetic member. Magnetic sensors comprising a nonmagnetic member including a material selected from the group consisting of: Bi, Sb and As, and alloys of Bi, Sb and As; a shunt conductor positioned adjacent to the nonmagnetic member; a first conductor electrically connected to the nonmagnetic member; and a second conductor electrically connected to the nonmagnetic member are also provided. Disc drives that include the read heads and sensors are also included.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to magnetic sensors having magnetoresistive read members that can be used in magnetic recording heads, as well as disc drives that include the sensors.  
         BACKGROUND OF THE INVENTION  
         [0002]    As magnetic data storage areal densities increase, read heads in disc drives need to become physically smaller in both the track-width and bit length directions. Therefore magnetic sensors used in the read heads need to be more sensitive to flux (φ media ) from the recording media. As the sensors become smaller, the demagnetization field in the free layer of a standard magnetic sensor, such as a spin-valve (SV) read head or a tunneling magnetoresistance (TMR) read head, becomes larger. Therefore, there is a reduction in the sensitivity of the read head to flux from the media that is ultimately limited by the superparamagnetic limit. This leads to a decreased signal-to-noise ratio. Attempting to increase magnetic stabilization normally will also lead to a decreased sensitivity to flux from the media.  
           [0003]    In addition, as the areal densities increase and the access times decrease (by increased media rotation speed), the data rate is naturally increasing. In addition to this natural increase in data rate, there is a desire for higher data rates. Standard magnetic sensors such as SV and TMR read heads may be limited in response time by the gyromagnetic frequency of the free layer. This frequency is on the order of a few GHz for the free layers of the devices (SV and TMR) that are being considered today.  
           [0004]    A possible solution to the above problems is to use a magnetic sensor including a nonmagnetic magnetoresistive element. A nonmagnetic magnetoresistive element is defined here as an element that is sensitive to magnetic fields, but does not contain a magnetic free layer as found in SV and TMR devices. Without a magnetic free layer there are no demagnetization fields that reduce sensitivity, there is no magnetic noise due to magnetic fluctuations in the free layer, there is no need for magnetically stabilizing the free layer, and the response time is not limited by the gyromagnetic frequency of the free layer.  
           [0005]    A magnetic sensor including a high electron mobility (μ e ) semiconductor and a high conductivity (μ e ) metal shunt has been previously proposed, and the effect was named Extraordinary Magneto-Resistance (EMR). However, this type of sensor has not been accepted for use in magnetic read heads.  
           [0006]    There is a need for a magnetic sensor that overcomes the limitations of spin-valve or tunneling magnetoresistance sensors, and which is suitable for use in magnetic read heads that can be used in disc drives.  
         SUMMARY OF THE INVENTION  
         [0007]    A magnetic read head comprises a magnetic sensor mounted on a back surface of a slider, wherein the magnetic sensor includes a nonmagnetic member, a conductive shunt positioned adjacent to the nonmagnetic member, a first conductor electrically connected to the nonmagnetic member, and a second conductor electrically connected to the nonmagnetic member.  
           [0008]    The nonmagnetic member can include a first surface lying generally parallel to an air bearing surface of the slider, and a second surface lying in a plane generally perpendicular to the air bearing surface, wherein the first conductor is electrically connected to the second surface of the nonmagnetic member and the second conductor is electrically connected to the second surface of the nonmagnetic member.  
           [0009]    A third conductor can be electrically connected to the second surface of the nonmagnetic member, and a fourth conductor can be electrically connected to the second surface of the nonmagnetic member, where the first and second conductors are positioned between the third and fourth conductors.  
           [0010]    In an alternative structure, the nonmagnetic member can include a first surface lying generally parallel to an air bearing surface of the slider, a second surface lying in a first plane generally perpendicular to the air bearing surface, and a third surface lying in a second plane generally perpendicular to the air bearing surface; and wherein the first conductor is electrically connected to the second surface of the nonmagnetic member and the second conductor is electrically connected to the third surface of the nonmagnetic member.  
           [0011]    Means can be provided for magnetically biasing the nonmagnetic member, and first and second shields can be positioned on opposite sides of the nonmagnetic member.  
           [0012]    The nonmagnetic member can be comprised of: Bi, Sb, As, alloys of Bi, Sb and As; or a semiconductor, including InSb, InAs and quantum wells made out of InSb or InAs.  
           [0013]    In another aspect, the invention encompasses a magnetic sensor comprising a nonmagnetic member including a material selected from the group consisting of: Bi, Sb and As, and alloys of Bi, Sb and As; a shunt conductor positioned adjacent to the nonmagnetic member; a first conductor electrically connected to the nonmagnetic member; and a second conductor electrically connected to the nonmagnetic member.  
           [0014]    The invention further encompasses a Hall Effect sensor comprising a nonmagnetic member comprised of a material selected from the group consisting of: Bi, Sb and As, and alloys of Bi, Sb and As; a first conductor connected to a first side of the nonmagnetic member; and a second conductor connected to a second side of the nonmagnetic member. The distance between the first and second conductors can be smaller than a height of the nonmagnetic member.  
           [0015]    Disc drives that include the read heads and sensors are also included. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]    [0016]FIG. 1 is a pictorial representation of a magnetic disc drive that can include magnetic heads constructed in accordance with this invention.  
         [0017]    [0017]FIG. 2 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0018]    [0018]FIG. 3 is a cross-sectional view of the magnetic recording head of FIG. 2.  
         [0019]    [0019]FIG. 4 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0020]    [0020]FIG. 5 is a cross-sectional view of the magnetic recording head of FIG. 4.  
         [0021]    [0021]FIG. 6 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0022]    [0022]FIG. 7 is a cross-sectional view of the magnetic recording head of FIG. 6.  
         [0023]    [0023]FIG. 8 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0024]    [0024]FIG. 9 is a cross-sectional view of the magnetic recording head of FIG. 8.  
         [0025]    [0025]FIG. 10 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0026]    [0026]FIG. 11 is a cross-sectional view of the magnetic recording head of FIG. 10.  
         [0027]    [0027]FIG. 12 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0028]    [0028]FIG. 13 is a cross-sectional view of the magnetic recording head of FIG. 12.  
         [0029]    [0029]FIG. 14 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0030]    [0030]FIG. 15 is a cross-sectional view of the magnetic recording head of FIG. 14.  
         [0031]    [0031]FIG. 16 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0032]    [0032]FIG. 17 is a cross-sectional view of the magnetic recording head of FIG. 16.  
         [0033]    [0033]FIG. 18 is an end view of a magnetic recording head including a nonmagnetic sensor constructed in accordance with the invention.  
         [0034]    [0034]FIG. 19 is a cross-sectional view of the magnetic recording head of FIG. 18.  
         [0035]    [0035]FIG. 20 is an isometric view of a slider having a magnetic sensor constructed in accordance with this invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0036]    Referring to the drawings, FIG. 1 is a pictorial representation of a disc drive  10  that can utilize magnetic recording heads having magnetic sensors constructed in accordance with this invention. The disc drive includes a housing  12  (with the upper portion removed and the lower portion visible in this view) sized and configured to contain the various components of the disc drive. The disc drive includes a spindle motor  14  for rotating at least one data storage medium  16  within the housing, in this case a magnetic disc. At least one arm  18  is contained within the housing  12 , with each arm  18  having a first end  20  with a recording and/or reading head or slider  22 , and a second end  24  pivotally mounted on a shaft by a bearing  26 . An actuator motor  28  is located at the arm&#39;s second end  24 , for pivoting the arm  18  to position the head  22  over a desired sector of the disc  16 . The actuator motor  28  is regulated by a controller that is not shown in this view and is well known in the art.  
         [0037]    [0037]FIG. 2 is an end view of a magnetic recording head  40  including a non-magnetic sensor  42  constructed in accordance with the invention, and FIG. 3 is a cross-sectional view of the magnetic recording head of FIG. 2 taken along line  3 - 3 . The read head includes a four-point contact, current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor  42  that can be mounted on the back of a slider  44 . The magnetic recording head  40  can further include other structures such as a write head, generally designated as item  46 . The sensor includes a high mobility, nonmagnetic member  48  having a generally rectangular cross-section and being positioned adjacent to a high conductivity shunt  50 . The high mobility member  48  includes a first surface  52  positioned adjacent to, and generally parallel to, an air bearing surface (ABS)  54  of the recording head  40 . The high mobility member  48  further includes a second surface  56  that lies in a plane generally perpendicular to the ABS. Four conductors  58 ,  60 ,  62  and  64  each include a portion adjacent to, and in electrical contact with, the second surface of the high mobility member and make electrical contact with the high mobility member. The shunt member is positioned adjacent to, and in electrical contact with, a third surface  66  of the high mobility member. Conductors  58  and  64  can be connected to a voltage or current source to supply a sense current (also called a bias current) to the high mobility member. Conductors  60  and  62  are positioned between conductors  58  and  64 , and serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , for storing data. The example of FIG. 3 shows a perpendicular magnetic recording medium  68 , having a magnetically hard layer  70  and a magnetically soft underlayer  72 . Arrows  74  illustrate the magnetization of portions of layer  70 . When the high mobility nonmagnetic member is subjected to a magnetic field  86 , it experiences a change in resistance resulting in a change in voltage between conductors  60  and  62 . A layer of insulation  76  separates the current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor from the remainder of the slider  40 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. The material outside of the two innermost electrodes can be the same high mobility material that is between the inner electrodes. Alternatively, that material could be a high conductivity material such as Cu, Au, Al or Ag. Shields may be incorporated into the structure of FIGS. 3 and 4. For example the material  82  between conductors  58  and  60 , and the material  84  between conductors  62  and  64  can be a magnetic shielding material such as NiFe, CoFe or CoNiFe.  
         [0038]    The head designs shown in FIGS. 2 and 3 would be most sensitive to magnetic fields  86  that are parallel to the ABS in the down track direction. This has been shown to be desirable for perpendicular recording, due to the voltage response not containing a DC component, and the response more closely resembling the voltage output that is seen in longitudinal recording. The magnetoresistance MR can be expressed as: MR=g(μ e H) 2 , where g is a geometrical factor, μ e  is the electron mobility, and H is the applied magnetic field. This response function will not result in the desired linear output for approximately ±200-500 Oe fields from the magnetic recording media. For this reason a bias field may need to be applied in order for the sensor to be operated in a linear region. Magnet  88  can be used to provide the bias field. Alternatively, the inner voltage conductors  60  and  62  may be offset with respect to the current conductors  58  and  64 . If the sensor only has two conductors instead of four, the g factor may be limited to values less than one and the option of biasing the sensor by offsetting the conductors is lost.  
         [0039]    [0039]FIG. 4 is an end view of an alternative magnetic recording head  90  constructed in accordance with the invention. FIG. 5 is a cross-sectional view of the magnetic recording head of FIG. 4 taken along line  5 - 5 . The magnetic recording head includes a three-point contact, current-in-the-plane (CIP) extraordinary magneto-resistance (EMR) sensor  92  mounted on the back of a slider  94 . The sensor includes a generally rectangular high mobility member  96  having a generally rectangular cross-section and positioned adjacent to a high conductivity shunt  98 . One surface  100  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  102  of the slider. A second surface  104  of the high mobility member lies in a plane generally perpendicular to the ABS. Three conductors  106 ,  108  and  110  each include a portion, which extends along the second surface of the high mobility member and is in electrical contact with the high mobility member. Conductors  106  and  110  can be connected to a current source to supply current to the high mobility member. Conductors  108  and  110  serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , for storing data. The magnetic recording medium  68  includes a magnetically hard layer  70  and a magnetically soft underlayer  72 . Arrows  74  illustrate the magnetization of portions of layer  70 . When the high mobility member is subjected to a magnetic field  112 , it experiences a change in resistance resulting in a change in voltage between conductors  108  and  110 . A layer of insulation  114  separates the CIP EMR sensor from the remainder of the slider  94 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction.  
         [0040]    [0040]FIG. 6 is an end view of an alternative magnetic recording head  120  constructed in accordance with the invention, and FIG. 7 is a cross-sectional view of the magnetic recording head of FIG. 2 taken along line  7 - 7 . The magnetic recording head  120  includes a four-point contact, transversely oriented current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor  122  mounted on the back of a slider  124 . The sensor includes a generally rectangular high mobility member  126  positioned adjacent to a high conductivity shunt  128 . One surface  130  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  132  of the slider. Four conductors  134 ,  136 ,  138  and  140  each including a portion which extends along a surface  144  of the high mobility member that lies in a plane generally perpendicular to the ABS, and is in electrical contact with the high mobility member. Conductors  134  and  140  can be connected to a voltage or current source to supply sense (or bias) current to the high mobility member and the shunt member. Conductors  136  and  138  are positioned between conductors  134  and  140 , and serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  146 , it experiences a change in resistance resulting in a change in voltage between conductors  136  and  138 . A layer of insulation  148  separates the CIP EMR sensor from the remainder of the slider  124 , which can include other well-known structures such as a write head in the area designated as item  150 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. A magnet  152  can be embedded in a layer of insulating material  154  to provide a magnetic bias field for the high mobility member.  
         [0041]    [0041]FIG. 8 is an end view of an alternative magnetic recording head  160  constructed in accordance with the invention, and FIG. 9 is a cross-sectional view of the magnetic recording head of FIG. 2 taken along line  9 - 9 . The recording head of FIGS. 8 and 9 is similar to that of FIGS. 6 and 7 except that the high mobility member and the shunt member are stacked in a different direction. The magnetic recording head  160  includes a four-point contact, transversely oriented current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor  162  mounted on the back of a slider  164 . The sensor includes a generally rectangular high mobility member  166  positioned adjacent to a high conductivity shunt  168 . One surface  170  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  172  of the slider. Four conductors  174 ,  176 ,  178  and  180  each include a portion that extends along a second surface  192  of the high mobility member and is in electrical contact with the high mobility member. Surface  192  lies in a plane generally perpendicular to the ABS. Conductors  174  and  180  can be connected to a voltage or current source to supply sense (or bias) current to the high mobility member and the shunt member. Conductors  176  and  178  are positioned between conductors  174  and  180 , and serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  182 , it experiences a change in resistance resulting in a change in voltage between conductors  176  and  178 . A layer of insulation  184  separates the CIP EMR sensor from the remainder of the slider  164 , which can include other well-known structures such as a write head in the area designated as item  186 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. A magnet  188  can be embedded in a layer of insulating material  190  to provide a magnetic bias field for the high mobility member.  
         [0042]    [0042]FIG. 10 is an end view of an alternative magnetic recording head  200  constructed in accordance with the invention, and FIG. 11 is a cross-sectional view of the magnetic recording head of FIG. 10 taken along line  11 - 11 . The magnetic recording head includes a two-point contact, current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor  202  mounted on the back of a slider  204 . The sensor includes a generally rectangular high mobility member  206  positioned adjacent to a high conductivity shunt member  208 . One surface  210  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  212  of the slider. Two conductors  214  and  216  extend along surfaces  218  and  220  on opposite sides of the high mobility member and are in electrical contact with the high mobility member. The conductors  214  and  216  can be connected to a voltage or current source to supply current to the high mobility member, and also serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  222 , it experiences a change in resistance resulting in a change in voltage between conductors  214  and  216 . A layer of insulation  224  separates the CIP EMR sensor from the remainder of the slider  204 , which can include other well-known structures such as a write head in the area designated as item  226 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. This sensor will be most sensitive to the vertical fields in the high mobility layer.  
         [0043]    [0043]FIG. 12 is an end view of an alternative magnetic recording head  230  constructed in accordance with the invention, and FIG. 13 is a cross-sectional view of the magnetic recording head of FIG. 12 taken along line  13 - 13 . The recording head of FIGS. 12 and 13 is similar to that of FIGS. 10 and 11 except that the high mobility member and the shunt member are stacked in a different direction and means are included for shielding the sensor in the down track direction and for magnetically biasing the sensor. The magnetic recording head includes a two-point contact, current-in-the-plane (CIP) extraordinary magnetoresistance (EMR) sensor  232  mounted on the back of a slider  234 . The sensor includes a generally rectangular high mobility member  236  positioned adjacent to a high conductivity shunt member  238 . One surface  240  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  242  of the slider. Two conductors  244  and  246  extend along surfaces  248  and  250  on opposite sides of the high mobility member  236  and are in electrical contact with the high mobility member. The conductors  244  and  246  can be connected to a voltage or current source to supply current to the high mobility member, and also serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  252 , it experiences a change in resistance resulting in a change in voltage between conductors  244  and  246 . A layer of insulation  254  separates the CIP EMR sensor from the remainder of the slider  234 , which can include other well-known structures such as a write head in the area designated as item  256 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. Shields  258  and  260  are mounted on opposites sides of the sensor in the down track direction. Shielding can be provided in the cross track direction by making the conductors out of a shield material. A magnet  262  can be positioned in a layer of insulating material  264  to provide a magnetic bias for the high mobility member.  
         [0044]    [0044]FIG. 14 is an end view of an alternative magnetic recording head  270  constructed in accordance with the invention, and FIG. 15 is a cross-sectional view of the magnetic recording head of FIG. 14 taken along line  15 - 15 . The magnetic recording head includes a two-point contact, current-perpendicular-to-the-plane (CPP) extraordinary magnetoresistance (EMR) sensor  272  mounted on the back of a slider  274 . The sensor includes a generally rectangular high mobility member  276  positioned adjacent to a high conductivity shunt member  278 . One surface  280  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  282  of the slider. Two conductors  284  and  286  extend along surfaces  288  and  290  on opposite sides of the high mobility member and are in electrical contact with the high mobility member. The conductors  284  and  286  can be connected to a voltage or current source to supply current to the high mobility member, and also serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a cross track magnetic field  292 , it experiences a change in resistance resulting in a change in voltage between conductors  284  and  286 . A layer of insulation  294  separates the CPP EMR sensor from the remainder of the slider  274 , which can include other well-known structures such as a write head in the area designated as item  296 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. Magnets  298  and  300  can be positioned in a layer of insulating material  302  to provide a magnetic bias for the high mobility member.  
         [0045]    [0045]FIG. 16 is an end view of an alternative magnetic recording head  310  constructed in accordance with the invention, and FIG. 17 is a cross-sectional view of the magnetic recording head of FIG. 16 taken along line  17 - 17 . The magnetic recording head includes a two-point contact, current-perpendicular-to-the-plane (CPP) extraordinary magnetoresistance (EMR) sensor  312  mounted on the back of a slider  314 . The sensor includes a generally rectangular high mobility member  316  positioned adjacent to a high conductivity shunt member  318 . One surface  320  of the high mobility member is positioned adjacent to an air bearing surface (ABS)  322  of the slider. Two conductors  324  and  326  extend along surfaces  328  and  330  on opposite sides of the high mobility member and are in electrical contact with the high mobility member. The conductors  324  and  326  can be connected to a voltage or current source to supply current to the high mobility member, and also serve as voltage sensing contacts. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  332 , it experiences a change in resistance resulting in a change in voltage between conductors  324  and  326 . A layer of insulation  334  separates the CPP EMR sensor from the remainder of the slider  314 , which can include other well-known structures such as a write head in the area designated as item  336 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction. A magnet  338  can be positioned in a layer of insulating material  340  to provide a magnetic bias for the high mobility member.  
         [0046]    [0046]FIG. 18 is an end view of an alternative magnetic recording head  350  constructed in accordance with the invention, and FIG. 19 is a cross-sectional view of the magnetic recording head of FIG. 18 taken along line  19 - 19 . The magnetic recording head includes a two-point shorted Hall Effect sensor  352  mounted on the back of a slider  354 . The sensor includes a generally rectangular Hall member  356 . One surface  358  of the Hall member is positioned adjacent to an air bearing surface (ABS)  360  of the slider. Two conductors  362  and  364  extend along opposite sides of the Hall member and are in electrical contact with the Hall member. Conductors  362  and  364  can be connected to a voltage or current source to supply current to the Hall member. In operation, the slider will be positioned adjacent to a magnetic recording medium  68 , which includes areas of magnetization  74 , representative of stored data. When the high mobility member is subjected to a magnetic field  366 , it experiences a change in resistance resulting in a change in voltage between conductors  362  and  364 . A layer of insulation  368  separates the Hall member sensor from the remainder of the slider  354 , which can include other well-known structures such as a write head in the area designated as item  370 . Arrow  78  indicates the cross track direction and arrow  80  indicates the down track direction.  
         [0047]    [0047]FIG. 20 is an isometric view of a slider  380  having a magnetic sensor  382  constructed in accordance with this invention. The sensor is mounted on a back surface  384  of the slider. In this example, the back surface  384  lies in a plane generally perpendicular to the air bearing surface. An edge  386  of the sensor is positioned adjacent to the air bearing surface  388  of the slider. By mounting the sensor on the back surface of the slider, as opposed to the underside of the slider shown in previous designs, this invention avoids many fabrication problems such as fabricating both a read head and write head that have a planar design, co-location of the proper ABS location for both the read head and write head, and getting both the read head and write head near the back of the slider to maintain a &lt;10 nm head-to-media separation.  
         [0048]    A method of making an unshielded CIP EMR head shown in FIGS. 2 and 3 can now be described.  
         [0049]    1) Start with a substrate such as AlTiC, Si, GaAs, or other suitable material.  
         [0050]    2) Deposit buffer layers as necessary. If no epitaxial growth on the substrate is needed, the buffer layer may include an insulator such as Al 2 O 3 , SiO 2 , AlON, SiON, or other suitable material. If epitaxial growth on the substrate is needed in order to achieve the desired properties in the high mobility layer, these layers would be deposited here, such as InSb, InAs, InAlAs, or other suitable material.  
         [0051]    3) Deposit the high mobility material over the entire wafer.  
         [0052]    4) Pattern the high mobility material using lithographic means such as optical or electron beam-lithography. Etch the high mobility material to define the dimension in the track width direction. The etch process could be a process such as reactive ion etching (RIE), inert ion beam etching (IBE), reactive ion beam etching (RIBE), or other suitable process.  
         [0053]    5) Deposit an insulating layer using a process such as ion beam deposition (IBD), electron beam or resistive evaporation, molecular beam epitaxy (MBE), sputtering, chemical vapor deposition, or other suitable process.  
         [0054]    6) Use lift-off to remove the insulator from the wafer, leaving the insulator locally planar with the high μ e  material. Processes such as IBE or chemical mechanical polishing (CMP) lift-off assist may be used as necessary.  
         [0055]    7) Pattern the high mobility material using lithographic means such as optical or electron beam lithography. Etch a cavity behind the high mobility material defining the dimension in the stripe height direction.  
         [0056]    8) Deposit the high conductivity, σ, material into the cavity using a process such as ion beam deposition (IBD), electron beam evaporation, molecular beam epitaxy (MBE), sputtering, or other suitable process. The high conductivity materials can be, for example, Au, Cu, Ag and Al.  
         [0057]    9) Cap the high σ layer with an insulation layer such as Al 2 O 3 , SiO 2 , AlON, and SiON, using a deposition process similar to the ones listed above.  
         [0058]    10) Use lift-off to remove the high σ material from the wafer, leaving it in the cavity. Processes such as IBE or chemical mechanical polishing (CMP) lift-off assist may be necessary.  
         [0059]    11) Define a box using lithographic process over the high mobility material and part of the high σ films.  
         [0060]    12) Deposit an insulating layer to help prevent shorting from the leads to the high σ material.  
         [0061]    13) Form the top leads using either a lift-off process or a deposition and etch process.  
         [0062]    Shields can be added to the CIP EMR head shown in FIGS. 2 and 3 using the following process.  
         [0063]    1) If a special buffer layer is not needed, shields and an insulator can be deposited after the insulating buffer layer, and then the high mobility film would be deposited on top of the insulator. If a special semiconductor buffer layer is needed, a ferromagnetic semiconductor such as GaMnN or GaAsMn may be used as a shield material.  
         [0064]    2) After forming the top leads, an insulator and top shield can be formed. This would be formed in much the same manner as the shields in a standard CIP spin-valve sensor.  
         [0065]    3) Side shields could be formed by replacing the high mobility material between leads  58  and  60 , and leads  62  and  64  with a soft magnetic material, such as NiFe, CoFe, CoNiFe or other suitable material. This should be relatively easy to do since the spacing between leads  62  and  64  is the critical dimension that determines the track width and the spacings between leads  58  and  60 , and  62  and  64  are not particularly important.  
         [0066]    Magnetic biasing can be added to the CIP EMR head shown in FIGS. 2 and 3 using the following process.  
         [0067]    1) A permanent magnet or a soft magnetic material exchange coupled to an antiferromagnetic material could be deposited before and/or after the high mobility material. This biasing layer would have a magnetization oriented perpendicular to the plane of the film in order to bias the sensor into a linear region. For designs in FIGS. 6-9 it would be relatively easy to add biasing by mounting a permanent magnet above the sensor (opposite of the sensor from the ABS), with a magnetization oriented perpendicular to the ABS. For the design in FIGS. 14-15 a permanent magnet could be mounted on the sides of the device. In an alternative structure, the shunt layer could be made of a permanent magnet with the magnetization oriented appropriately.  
         [0068]    Similar processing as used for FIGS. 2 and 3 could be used for the devices shown in FIGS. 4-19. Only the key differences will be highlighted.  
         [0069]    The key difference between FIGS. 2 and 3, and FIGS. 4 and 5 is just the orientation of the high mobility and high σ films with respect to the ABS. This would not have much effect on the processing. If the high σ material was made of soft magnetic material, such as NiFe, CoFe, CoNiFe, this would act as a side shield. If after patterning the high mobility material an insulator/shield material combination was deposited, a side shield would be formed on the other side of the sensor.  
         [0070]    The key difference between FIGS. 2 and 3, and FIGS. 6-9 is the orientation of the high mobility and high σ films. In FIGS. 6-9 the films are deposited one on top of the other instead of one behind the other. The high mobility and high a materials are stacked in the down track direction. In general, they can be stacked in either order (either one can be on top) and the leads will contact the high mobility material. If the high σ material includes a shield material, it will act as a down track shield. A two lead, side lead structure could also be used with a high mobility and high σ arrangement as shown in FIGS. 2 and 3. This two lead, side lead structure may make it easier to incorporate side shields.  
         [0071]    The devices shown in FIGS. 14-17 are different from those described above in that the current in these devices is traveling perpendicular to the plane of the films. For these devices, the leads can be made of a shield material, which would provide down track shielding. In FIGS. 16 and 17, the high σ material could be a shield material and it would provide cross track shielding.  
         [0072]    [0072]FIGS. 18 and 19 show a simplified CIP, shorted Hall Effect sensor. The sensor includes a high mobility material between two conductors. This design could also be made using a CPP structure. Incorporating shields and biasing would be straightforward for both the CIP and CPP designs. The field from the media would cause the electrons to travel in an arc within the high mobility material, and therefore see a higher resistance between the conductors. The dimensions would need to be selected such that a reverse voltage (Hall voltage) is not set up that counter balances the Lorentz force from the applied field. This would be the case for a conductor-to-conductor spacing smaller than the stripe height of the sensor. That is, the distance between the first and second conductors is small compared to the height of the nonmagnetic member such that an applied magnetic field produces a change in electrical resistance between the first and second conductors.  
         [0073]    The sensors of this invention can use semimetals and some of the designs can use either a semimetal or a narrow bandgap semiconductor. In a semimetal, the valance and conduction band overlap slightly, such as Bi, Sb and As. These materials also have very high mobilities. If the mobility is calculated for Bi using bulk parameters, it is larger than that measured for the best semiconductors. Using μ=1/(pen), where p is the resistivity, e is the electron charge, and n is the electron carrier density, one can calculate μ e . Using p=116 μOhm-cm and n=2.88e 17  cm 3  for Bi, one calculates μ (Bi)=18.7 m 2 /V/sec. InSb, on the other hand, has a maximum μ e =7 m 2 /V/sec. This high mobility has not been previously realized for Bi, possibly because the previous measurements are macroscopic measurements. For the device sizes of interest in the present invention (&lt;100 nm), the device size can be made smaller than the grain size. This may make the effective mobility for the electrons within the device much higher than that measured in a macroscopic test structure where the electrons encounter many grain boundaries. Annealing Bi and/or choosing a good seedlayer material may easily result in grains larger than 100 nm. Due to the low melting point of Bi, anneal temperatures do not need to be large in order to increase the grain size significantly (&lt;270° C.). In addition, alloying Bi with other materials to expand or contract the lattice may result in an increased mobility, similar to adding Ge to Si to increase the mobility of the Si. By having a high mobility metal that can be sputtered, instead of an MBE grown quantum well, the structures of this invention can be more easily fabricated than previously proposed nonmagnetic sensors.  
         [0074]    The sensors of this invention can be made using materials that are compatible with the current magnetic recording head processing and can be fabricated on the back of a slider instead of on the bottom of the slider. The various examples also show means for incorporating magnetic shielding and/or magnetic biasing if needed.  
         [0075]    In the above description, the word “adjacent” has been used to describe a relationship of the position of various elements with respect to each other. It should be understood that adjacent means both in contact with, or near to. For example, a thin layer of material, such as a buffer layer can be positioned between adjacent layers, but the layers would still fall within the meaning of the word adjacent.  
         [0076]    While the present invention has been described in terms of several examples, it will be apparent to those skilled in the art that various changes can be made to the disclosed examples without departing from the scope of the invention as defined by the following claims.