System and method for fixing a direction of magnetization of pinned layers in a magnetic field sensor

Abstract

A spin valve GMR sensor configured in a bridge configuration is provided. The bridge includes two spin valve element pairs. The spin valve elements include a free layer, a space layer, a pinned layer, and a bias layer. The bias layer includes a first bias layer and a second bias layer. The first and second spin valve element pairs are formed on separate metal layers and a current pulse is applied to the metal layers, which sets the direction of magnetization in the pinned layer of the first pair of spin valve elements to be antiparallel to the direction of magnetization in the pinned layer of the second pair of spin valve elements. The same effect can be accomplished by making the pinned layer substantially thicker than the second bias layer in the first spin valve element pair and the pinned layer is substantially thinner than the second bias layer in the second spin valve element pair and applying a magnetic field to the first and the second spin valve element pairs.

1 - 9 . (canceled)  
     
     
         10 . A method of fabricating a spin valve giant magnetoresistive sensor in a Wheatstone bridge configuration, comprising in combination: 
 depositing at least one metal layer;    depositing spin valve element layers to form spin valve elements;    depositing dielectric layers substantially between the at least one metal layer and the spin valve elements; and    applying a current pulse to the at least one metal layer.    
     
     
         11 . The method of  claim 10 , wherein a separate metal layer is deposited for each spin valve element.  
     
     
         12 . The method of  claim 10 , wherein a separate metal layer is deposited for each spin valve element pair.  
     
     
         13 . The method of  claim 10 , wherein the spin valve element layers include a free layer, a space layer, a pinned layer, and a bias layer.  
     
     
         14 . The method of  claim 10 , wherein the current pulse is applied after forming the spin valve elements.  
     
     
         15 . The method of  claim 10 , wherein the current pulse sets a direction of magnetization in the spin valve elements.  
     
     
         16 . The method of  claim 10 , wherein the current pulse is applied for approximately 1 microsecond and has a peak greater than 100 milliamperes.  
     
     
         17 . The method of  claim 10 , wherein the current pulse generates a first magnetic field in a first pair of spin valve elements and a second magnetic field in a second pair of spin valve elements.  
     
     
         18 . The method of  claim 17 , wherein the first magnetic field is in a direction substantially opposite to that of the second magnetic field.  
     
     
         19 . The method of  claim 17 , wherein the first magnetic field and the second magnetic field set a direction of magnetization in a pinned layer of the first spin valve element pair to be substantially antiparallel to a direction of magnetization in a pinning layer of the second spin valve element pair.  
     
     
         20 - 38 . (canceled)