Patent ID: 9007725
Filing Date: 2015-04-14
Classification: G11B

Abstract:
1. A magnetic sensor comprising: a first ferromagnetic free layer that is not magnetically pinned; a second ferromagnetic free layer that is not magnetically pinned; a non-magnetic spacer layer disposed between the first and second ferromagnetic free layers; wherein the first ferromagnetic free layer comprises a first plurality of ferromagnetic sub-layers that includes a first cobalt iron sub-layer that is in contact with the non-magnetic spacer layer, and a first amorphous cobalt boron sub-layer that is not in contact with the non-magnetic spacer layer; and wherein the second ferromagnetic free layer comprises a second plurality of ferromagnetic sub-layers that includes a second cobalt iron sub-layer that is in contact with the non-magnetic spacer layer, and a second amorphous cobalt boron sub-layer that is not in contact with the non-magnetic spacer layer; wherein each of the first and second cobalt iron sub-layers has a composition Co