Direct evidence of spin filtering across MnFe2O4 tunnel barrier by Meservey-Tedrow experiment.

A spin filtering effect has been evidenced in epitaxial MnFe2O4 tunnel barriers directly by Meservey-Tedrow experiments. The asymmetry of the Zeeman-split tunneling conductance curves of the superconducting Al spin analyzer in Pt(111)/MnFe2O4(111)/γ-Al203(111)/A1 tunnel junctions revealed a positive spin-polarization (up to + 9%), proving the potential of manganese ferrite for generation of a spin-polarized current. A negatively polarized spin filtering being expected theoretically, different mechanisms are discussed to explain both sign and amplitude of the measured spin-polarization. [ABSTRACT FROM AUTHOR]