Heusler compounds are promising materials for spintronics with adjustable electronic properties including 100% spin polarization at the Fermi energy. We investigate the electronic states of ${\mathrm{AlO}}_x$ capped epitaxial thin films of the ferromagnetic half-metal ${\mathrm{Co}}_2\mathrm{MnSi}$ ex situ by soft x-ray angular resolved photoemission spectroscopy (SX-ARPES). Good agreement between the experimental SX-ARPES results and photoemission calculations including surface effects was obtained. In particular, we observed in line with our calculations a large photoemission intensity at the center of the Brillouin zone, which does not originate from bulk states, but from a surface resonance. This provides strong evidence for the validity of the previously proposed model based on this resonance, which was applied to explain the huge spin polarization of ${\mathrm{Co}}_2\mathrm{MnSi}$ observed by angular-integrating UV-photoemission spectroscopy.

• Received 9 April 2019
• Revised 16 May 2019

DOI:https://doi.org/10.1103/PhysRevB.99.174432