Magnetic structure free layer stabilization

Abstract

A magnetic layered structure is presently disclosed comprising a pinned layer, a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer, a free layer, a second anti-ferromagnetic layer that biases the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer, and a tuning layer positioned between and in contact with the second anti-ferromagnetic layer and the free layer that tunes free layer bias to a desired level.

What is claimed is: 
     
         1 . A magnetic layered structure comprising:
 a pinned layer;   a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer;   a free layer;   a second anti-ferromagnetic layer that biases the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer; and   a tuning layer positioned between and in contact with the second anti-ferromagnetic layer and the free layer, wherein the tuning layer tunes free layer bias to greater than 250 Oresteds (Oe).   
     
     
         2 . The magnetic layered structure of  claim 1 , further comprising:
 one or more side shields positioned adjacent the free layer along a major plane of the free layer.   
     
     
         3 . The magnetic layered structure of  claim 2 , wherein the side shields include a soft magnetic material. 
     
     
         4 . The magnetic layered structure of  claim 2 , wherein the side shields include a non-magnetic material. 
     
     
         5 . The magnetic layered structure of  claim 1 , further comprising:
 two electrodes, each positioned on opposite sides of the layered structure, configured to conduct current through the layered structure along an axis approximately perpendicular to a major plane of the free layer.   
     
     
         6 . The magnetic layered structure of  claim 1 , further comprising:
 a spacer layer that magnetically separates the pinned layer from the free layer.   
     
     
         7 . The magnetic layered structure of  claim 1 , further comprising:
 a capping layer that protects the second anti-ferromagnetic layer from post deposition damage.   
     
     
         8 . The magnetic layered structure of  claim 1 , wherein the pinned layer, first anti-ferromagnetic layer, free layer, and second anti-ferromagnetic layer comprise a read element sensor. 
     
     
         9 . The magnetic layered structure of  claim 1 , wherein approximately perpendicular is perpendicular +/−15 degrees. 
     
     
         10 . The magnetic layered structure of  claim 1 , wherein the first and second anti-ferromagnetic layers comprise IrMn or PtMn and have a thickness greater than or equal to 30 Å and less than or equal to 250 Å. 
     
     
         11 . The magnetic layered structure of  claim 1 , wherein the tuning layer decouples the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment. 
     
     
         12 . The magnetic layered structure of  claim 1 , wherein the free layer comprises a first free layer and a second free layer. 
     
     
         13 . A method of biasing a magnetic layered structure, comprising:
 defining a magnetic orientation of a pinned layer using a first anti-ferromagnetic layer;   biasing a magnetic orientation of a free layer using a second anti-ferromagnetic layer, wherein the defined magnetic orientation of the pinned layer is approximately perpendicular to the biased magnetic orientation of the free layer; and   tuning free layer bias to greater than 250 Oe using a tuning layer positioned between and in contact with the second anti-ferromagnetic layer and the free layer.   
     
     
         14 . The method of  claim 13 , further comprising:
 shielding the free layer from external electromagnetic and/or thermal interference using one or more side shields positioned adjacent the free layer along a major plane of the free layer.   
     
     
         15 . The method of  claim 13 , further comprising:
 conducting current along an axis approximately perpendicular to a major plane of the free layer between two electrodes positioned on opposite sides of the first anti-ferromagnetic layer, pinned layer, free layer, and second anti-ferromagnetic layer.   
     
     
         16 . The method of  claim 13 , further comprising:
 decoupling the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment.   
     
     
         17 . A transducer for a magnetic disc drive comprising:
 a reader, including
 a pinned layer; 
 a first anti-ferromagnetic layer that defines a magnetic orientation of the pinned layer; 
 a free layer; 
 a second anti-ferromagnetic layer that biases the free layer to a magnetic orientation approximately perpendicular to the magnetic orientation of the pinned layer; and 
 a tuning layer positioned between and in direct contact with the second anti-ferromagnetic layer and the free layer, wherein the tuning layer tunes free layer bias to greater than 250 Oe. 
   
     
     
         18 . The transducer of  claim 17 , wherein the reader further includes one or more side shields positioned adjacent the free layer along a major plane of the free layer that shields the free layer from external electromagnetic interference. 
     
     
         19 . The transducer of  claim 17 , wherein the reader further includes two electrodes, each positioned on opposite sides of the layered structure, configured to conduct current through the layered structure along an axis approximately perpendicular to a major plane of the free layer. 
     
     
         20 . The transducer of  claim 17 , wherein the tuning layer decouples the free layer and the second anti-ferromagnetic layer while reducing dispersion of a free layer magnetic moment.