Point-contact Andreev spectroscopy on thin [formula omitted] Heusler films

Abstract

Heusler films with L 2 1 and B2 structure are deposited simultaneously on amorphous carbon films, Si(1 0 0) surfaces, and in situ cleaved InAs(1 1 0) surfaces by coevaporation of Ni and the alloy MnIn. Morphology, structure, and stoichiometry are investigated with transmission-electron microscopy, electron diffraction, and X-ray spectroscopy. The almost perfect lattice match supports highly oriented growth of Ni 2 MnIn on InAs, which is proven by electron diffraction under grazing incidence. The electrical resistivity of thin films on Si show metallic behavior. At temperatures of liquid helium point-contact Andreev reflection spectroscopy is performed on films grown on Si(1 0 0) and in situ cleaved InAs(1 1 0) surfaces yielding spin polarizations comparable to the ones of Fe, Ni, Co, and permalloy ( Ni 80 Fe 20 ) .