Electronic structure and symmetry of valence states of epitaxial NiTiSn and NiZr$_{0.5}$Hf$_{0.5}$Sn thin films by hard x-ray photoelectron spectroscopy

TL;DR

This study investigates the electronic structure and symmetry of valence states in epitaxial NiTiSn and NiZr$_{0.5}$Hf$_{0.5}$Sn thin films using polarization-dependent hard x-ray photoelectron spectroscopy, revealing insights into their in-gap states and similarity to bulk properties.

Contribution

It demonstrates the use of polarization-dependent hard x-ray photoelectron spectroscopy to analyze symmetry and electronic states in Heusler compound thin films, highlighting differences from bulk materials.

Findings

Films show more in-gap states than bulk samples.

NiTiSn-based films have electronic structures similar to bulk materials.

Linear dichroism distinguishes valence state symmetry.

Abstract

The electronic band structure of thin films and superlattices made of Heusler compounds with NiTiSn and NiZr$_{0.5}$Hf$_{0.5}$Sn composition was studied by means of polarization dependent hard x-ray photoelectron spectroscopy. The linear dichroism allowed to distinguish the symmetry of the valence states of the different types of layered structures. The films exhibit a larger amount of {\it "in-gap"} states compared to bulk samples. It is shown that the films and superlattices grown with NiTiSn as starting layer exhibit an electronic structure close to bulk materials.