Reader with decoupled magnetic seed layer

Abstract

An apparatus comprising a base shield and a sensor stack, wherein the base shield is separated from the sensor stack via a first soft magnetic layer that is magnetically decoupled form the base shield.

1 . An apparatus comprising:
 a base shield; and   a sensor stack,   wherein the base shield is separated from the sensor stack via a first soft magnetic layer that is magnetically decoupled form the base shield.   
     
     
         2 . The apparatus of  claim 1  wherein the first soft magnetic layer is magnetically decoupled from the base shield using a layer of non-magnetic material. 
     
     
         3 . The apparatus of  claim 1  further comprising a top shield, wherein the top shield is separated from the sensor stack via a second soft magnetic layer that is magnetically decoupled form the top shield. 
     
     
         4 . The apparatus of  claim 3  wherein the second soft magnetic layer is magnetically decoupled from the top shield using a layer of non-magnetic material. 
     
     
         5 . The apparatus of  claim 1 , wherein the sensor stack is located on a read head of a disc drive. 
     
     
         6 . The apparatus of  claim 1 , wherein the first soft magnetic layer is made of at least one of NiFe, NiFeCu, and NiCoFe. 
     
     
         7 . The apparatus of  claim 1 , wherein the exchange of magnetic energy between the soft magnetic layer and the base shield is substantially zero. 
     
     
         8 . An apparatus comprising:
 a base shield;   a sensor stack; and   a base seed layer separating the base shield from the sensor stack,   wherein the base seed layer comprises:
 a base coupled seed section that is coupled with the base shield; and 
 a base uncoupled seed section that is uncoupled with the base shield, wherein the base uncoupled seed section covers a base window surrounding the sensor stack. 
   
     
     
         9 . The apparatus of  claim 8  wherein the dimension of the base window beyond the sensor in a direction perpendicular to the direction of the sensor stack is at least twice the dimension of the spacing between the base shield and the top shield. 
     
     
         10 . The apparatus of  claim 9 , wherein the base uncoupled seed section is uncoupled from the base shield using a layer of non-magnetic material. 
     
     
         11 . The apparatus of  claim 8  further comprising a top shield located on a side of the sensor stack opposite the base shield, the top shield separated from the sensor stack with a top seed layer. 
     
     
         12 . The apparatus of  claim 11 , wherein the top seed layer comprises:
 a top coupled seed section that is coupled with the top shield; and   a top uncoupled seed section that is uncoupled with the top shield, wherein the top uncoupled seed section covers a top window surrounding the sensor stack.   
     
     
         13 . The apparatus of  claim 12 , wherein the top uncoupled seed section is uncoupled from the top shield using a layer of non-magnetic material. 
     
     
         14 . The apparatus of  claim 12 , wherein the dimension of the top window beyond the sensor in a direction perpendicular to the direction of the sensor stack is at least twice the dimension of the spacing between the base shield and the top shield. 
     
     
         15 . The apparatus of  claim 14 , wherein the base coupled seed section and the top coupled seed section are made of at least one of NiFe, NiFeCu, and NiCoFe. 
     
     
         16 . A reader sensor comprising:
 a sensor stack;   a base seed layer separating the sensor stack from a base shield, wherein the base seed layer is at least partially uncoupled with the base shield.   
     
     
         17 . The reader sensor of  claim 16 , further comprising a top seed layer separating the sensor stack from a top shield, wherein the top seed layer is at least partially uncoupled with the top shield 
     
     
         18 . The reader sensor of  claim 16  wherein dimension of a section of the base seed layer, which is uncoupled with the base shield, in a direction perpendicular to the direction of the sensor stack is at least twice the dimension of the spacing between the base shield and the top shield. 
     
     
         19 . The reader sensor of  claim 18  wherein dimension of a section of the top seed layer, which is uncoupled with the top shield, in a direction perpendicular to the direction of the sensor stack is extends beyond the sensor stack by at least twice the dimension of the spacing between the base shield and the top shield. 
     
     
         20 . The reader sensor of  claim 13  wherein the sensor stack is located on a read head of a disc drive.