Resonant Tunneling Magnetoresistive in Antiferromagnetically coupled Fe-based Structures with Multilayered Si/Ge Spacers

We report on the experimental evidence of the tunneling magnetoresistance (TMR) effect near 3% and its inversion in strongly antiferromagnetically coupled Fe(001)/([Si(0.2 nm)/Ge(0.2 nm)](*)5)/Fe epitaxial structures with diffused interfaces. We explain the inversion of TMR with biasing voltage by resonant tunneling across impurity states with weak spin split Delta E similar to 10 meV and spin-dependent filtering in the spacer layer. The resonant tunneling is manifested in spin-dependent resonances close to zero biasing voltages related to antiferromagnetic coupling across impurity states. (c) 2006 American Institute of Physics