Band diagrams of spin tunneling junctions La0.6Sr0.4MnO3∕Nb:SrTiO3 and SrRuO3∕Nb:SrTiO3 determined by <i>in situ</i> photoemission spectroscopy

Abstract

The authors report on the band diagram for epitaxial Schottky junctions of ferromagnetic metallic oxides [half-metallic ferromagnet La0.6Sr0.4MnO3 (LSMO) and itinerant ferromagnet SrRuO3 (SRO)] on Nb-doped SrTiO3 (Nb:STO) semiconductor substrates using in situ photoemission spectroscopy. The ideal Schottky barrier is formed in SRO/Nb:STO junctions with Schottky barrier height (SBH) of 1.2±0.1eV, while the measured SBH of LSMO/Nb:STO (1.2±0.1eV) is much larger than the prediction from the Schottky-Mott rule (0.7±0.1eV). These results suggest that a certain interface dipole is formed at the LSMO/Nb:STO interface.