Magnetic tunnel junctions with large tunneling magnetoresistance and small saturation fields

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.