There is a continuing need for greater sensitivity in magnetic tunnel junction (MTJ) sensors. We have found a new approach to achieving large tunneling magnetoresistance (TMR) with a very soft free layer. The high TMR is achieved by conventional means of annealing a bottom pinned MTJ that has Ta and Ru capping layers. The soft free layer is achieved by etching almost to the MgO tunnel barrier and depositing a thick soft magnetic film. The results are far superior to annealing the MTJ with the thick soft layer already deposited.
Magnetic tunnel junctions with large tunneling magnetoresistance and small saturation fields
W. F. Egelhoff, V. E. Höink, J. W. Lau, W. F. Shen, B. D. Schrag, G. Xiao; Magnetic tunnel junctions with large tunneling magnetoresistance and small saturation fields. J. Appl. Phys. 1 May 2010; 107 (9): 09C705. https://doi.org/10.1063/1.3358609
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