Monday, December 22, 2008

US Patent 7466523 - Nanotube spin valve

Spintronics has found useful applications in magnetic high density memory storage and sensing devices. This patent teaches ballistic transport of spin via a nanotube channel which may improve the efficiency of such applications. Claim 1 reads:

1. A spin valve device comprising:

a ferromagnetic free layer whose magnetization changes in a magnetic signal field,

a ferromagnetic pinned layer whose magnetization remains unchanged in the magnetic signal field,

a single or a plurality of carbon nanotubes reside between said ferromagnetic free layer and said pinned layer, and are in electrical contact with the two, wherein said carbon nanotube each having a substantially cylindrical wall, having a submicron diameter, a length measured in a direction perpendicular to the diameter, and the length being greater than the diameter, wherein the plane of said ferromagnetic pinned layer is parallel to the plane of said free layer, and said carbon nanotubes are vertically aligned and perpendicular to the planes of said pinned and said free layers, and an electrical current passes from one ferromagnetic layer to the other via said carbon nanotubes during the device operation.