Patent ID: 8760817

Claim:
A spin accumulation sensor, comprising: a non-magnetic spin transport conductive layer; a reference layer structure located away from a free layer structure, the reference layer structure including a magnetic reference layer and a first thin contact layer, the first contact layer being located between the magnetic reference layer and the non-magnetic spin transport conductive layer; wherein the free layer structure is located at the air bearing surface, the free layer structure including a magnetic free layer, a second contact layer and a spin diffusion layer, the contact layer being located between the free magnetic layer and the non-magnetic spin transport conductive layer; first and second electrically conductive magnetic shields, the reference layer structure, free layer structure and nonmagnetic spin transport conductive layer being located between the first and second magnetic, electrically conductive shields; and a current or voltage source electrically connected with the reference layer structure so as to apply an electric current through the reference layer structure resulting in a spin current in the non-magnetic spin transport conductive layer, the current or voltage source also being connected to a common electric ground connection, the connection with the common ground being made at a location that is separated from the reference layer structure by a distance that is at least one or more times the spin diffusion length of the spin-conductive layer; and circuitry for measuring a signal voltage between a portion of the free layer structure and the common electric ground.