Element-specific density of states of Co2MnGe revealed by resonant photoelectron spectroscopy

Abstract

Resonant photoelectron spectroscopy at the Co and Mn $2p$ core absorption edges of half-metallic ${\mathrm{Co}}_{2}\mathrm{MnGe}$ has been performed to determine the element-specific density of states (DOS). A significant contribution of the Mn $3d$ partial DOS near the Fermi level $({E}_{\mathrm{F}})$ was clarified by measurement at the Mn $2p$ absorption edge. Further analysis by first-principles calculation revealed that it has ${t}_{2\mathrm{g}}$ symmetry, which must be responsible for the electrical conductivity along the line perpendicular to the film plane. The dominant normal Auger contribution observed at the Co $2p$ absorption edge indicates delocalization of photoexcited Co $3d$ electrons. The difference in the degrees of localization of the Mn $3d$ and Co $3d$ electrons in ${\mathrm{Co}}_{2}\mathrm{MnGe}$ is explained by the first-principles calculation. Our findings of the element-/orbital-specific electronic states near ${E}_{\mathrm{F}}$ will pave the way for future interface design of magnetic tunneling junctions to overcome the temperature-induced reduction of the magnetoresistance.