# Surface resonance of the Heusler half metal Co2MnSi probed by SX-ARPES

## TL;DR

This study uses SX-ARPES to investigate surface resonances in Co2MnSi, revealing surface effects that support its high spin polarization, crucial for spintronics applications.

## Contribution

First direct observation of surface resonance in Co2MnSi using SX-ARPES, validating models explaining its high spin polarization.

## Key findings

- Surface resonance significantly contributes to photoemission intensity.
- Experimental results agree with theoretical calculations including surface effects.
- Supports the model explaining high spin polarization in Co2MnSi.

## Abstract

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 AlOx capped epitaxial thin films of the ferromagnetic half metal Co2MnSi 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 Co2MnSi observed by angular-integrating UV-photoemission spectroscopy.