Unveiling spin-dependent unoccupied electronic states of Co2MnGe (Ga) film via Ge (Ga) L2,3 absorption spectroscopy

Abstract

X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) spectroscopy were applied at the Ge (Ga) ${L}_{2,3}$ edge to unravel the spin-resolved unoccupied electronic states of ${\mathrm{Co}}_{2}\mathrm{Mn}\mathrm{Ge}$ (Ga). Complicated spectral features were observed in both XAS and XMCD spectra. For their interpretation, we compared the experimental XAS and XMCD spectra with the calculated Ge (Ga) $4s$ and $4d$ orbital partial density of states. The comparison enabled a qualitative explanation of the XMCD spectra as the difference between the majority- and minority-spin unoccupied density of states summed over the $4s$ and $4d$ orbitals. Our finding provides a new approach to uncover the spin-split partial density of states above the Fermi level.