Magnetic sensor

Abstract

A magnetic sensor senses an external magnetic field using a spin-filtered sensor current flowing through a non-magnetic layer.

What is claimed is:  
     
         1 . A magnetic sensor that senses an external magnetic field using a spin-filtered sensor current flowing through a non-magnetic layer.  
     
     
         2 . The magnetic sensor as claimed in  claim 1 , further comprising: 
 a pair of ferromagnetic bodies provided on the non-magnetic layer and positioned parallel to an axis of magnetization of each of the ferromagnetic bodies; and    a power source that uses the ferromagnetic bodies as electrodes to supply the sensor current.    
     
     
         3 . The magnetic sensor as claimed in  claim 1 , wherein: 
 a ferromagnetic film is provided on the non-magnetic layer; and    an axis of magnetization of the ferromagnetic layer is formed either parallel to or opposite to a direction of electron spin of the sensor current.    
     
     
         4 . The magnetic sensor as claimed in claim  3 , wherein the ferromagnetic layer is formed as a free layer constituting either an anisotropic magneto-resistive film or a giant magneto-resistive film.  
     
     
         5 . The magnetic sensor as claimed in  claim 4 , wherein the giant magneto-resistive film constitutes a spin-valve structure.  
     
     
         6 . The magnetic sensor as claimed in  claim 4 , wherein the non-magnetic layer is formed from a material selected from a group consisting of aluminum, copper, chromium, or an alloy of these metals.  
     
     
         7 . The magnetic sensor as claimed in  claim 2 , wherein: 
 the non-magnetic layer is formed of a semiconductor material; and    the axis of magnetization of one of the pair of ferromagnetic bodies changes so as to detect an external magnetic field.    
     
     
         8 . The magnetic sensor as claimed in  claim 7 , wherein the semiconductor material is indium aluminum arsenide.  
     
     
         9 . The magnetic sensor as claimed in  claim 7 , wherein the semiconductor material is indium gallium arsenide.  
     
     
         10 . The magnetic sensor as claimed in  claim 1 , wherein the ferromagnetic body is formed from a material selected from a group consisting of iron, cobalt, nickel, or an alloy of these metals.  
     
     
         11 . A device for magnetically recording and reproducing information to and from a recording medium, the magnetic head unit comprising a magnetic sensor that senses an external magnetic field using a spin-filtered sensor current flowing through a non-magnetic layer.