Co-Fe supermalloy free layer for magnetic tunnel junction heads

摘要

A magnetic tunnel junction sensor is provided having a laminated free layer comprising a first sublayer formed of Co—Fe in contact with a spacer layer and a second sublayer formed of Ni—Fe—Mo. The Ni—Fe—Mo material of the second sublayer has a magnetocrystalline anisotropy constant, k, that is much smaller than that of Ni—Fe. Due to the small value of k of the Ni—Fe—Mo material used to fabricate the second sublayer of the free layer, the thickness of the Co—Fe first sublayer may be increased to improve manufacturability while retaining a low net stiffness of the free layer for high sensitivity of the MTJ sensor in response to signal fields from data magnetically recorded on a disk. The thicker Co—Fe first sublayer results in a higher magnetoresistance coefficient of the improved MTJ sensor.