Andreev reflection in ferrimagnetic CoFe2O4/SrRuO3 spin filters

Abstract

We have performed point contact spectroscopy measurements on a sample constituted by a metallic ferromagnetic oxide (SrRuO_3) bottom electrode and a tunnel ferrimagnetic (CoFe_2O_4) barrier. Andreev reflection is observed across the tunnel barrier. From the comparison of Andreev reflection in SrRuO3 and across the CoFe_2O_4 barrier we infer that the ferrimagnetic barrier has a spin filter efficiency not larger than +13%. The observation of a moderate and positive spin filtering is discussed in the context of the microstructure of the barriers and symmetry-related spin filtering effects.

13 pages, 5 figures. To appear in Phys. Rev. B.

References in corpus (4)

• Electronic structure of normal and inverse spinel ferrites from first principles
• The role of critical current on point contact Andreev Reflection spectrum between a normal metal and a superconductor
• Room temperature spin filtering in epitaxial cobalt-ferrite tunnel barriers
• Subharmonic gap structures and Josephson effect in MgB2/Nb micro-constrictions