Effect of free layer thickness and shape anisotropy on the transfer curves of MgO magnetic tunnel junctions

Abstract

A study of the combined effect of CoFeB free layer thickness, shape anisotropy, and annealing temperature on the transfer curves of MgO based magnetic tunnel junctions is presented. The response of the free layer changes gradually as its thickness decreases and shows hysteresis-free response for CoFeB⩽15.5Å. For junctions with CoFeB=15.5Å, the onset of hysteresis-free response depends on junction area and annealing temperature. Linearized magnetic tunnel junctions with dimensions down to 1.5×3μm2 and sensitivity as high as 7.7%∕Oe were achieved.