Effect of chemical disorder on NiMnSb investigated by Appearance Potential Spectroscopy: a theoretical study

TL;DR

This study investigates how chemical disorder affects the electronic and magnetic properties of NiMnSb, combining ab-initio calculations with spectroscopy measurements to understand its impact on spin polarization.

Contribution

It provides a theoretical analysis of chemical disorder effects on NiMnSb's electronic structure using the Coherent Potential Approximation, supported by spectroscopy data.

Findings

Chemical disorder influences the unoccupied electronic density of states.

Spin polarization is sensitive to structural and stoichiometric variations.

Theoretical spectra align with experimental Appearance Potential Spectroscopy results.

Abstract

The half-Heusler alloy NiMnSb is one of the local-moment ferromagnets with unique properties for future applications. Band structure calculations predict exclusively majority bands at the Fermi level, thus indicating {100%} spin polarization there. As one thinks about applications and the design of functional materials, the influence of chemical disorder in these materials must be considered. The magnetization, spin polarization, and electronic structure are expected to be sensitive to structural and stoichiometric changes. In this contribution, we report on an investigation of the spin-dependent electronic structure of NiMnSb. We studied the influence of chemical disorder on the unoccupied electronic density of states by use of the ab-initio Coherent Potential Approximation method. The theoretical analysis is discussed along with corresponding spin-resolved Appearance Potential Spectroscopy measurements. Our theoretical approach describes the spectra as the fully-relativistic self-convolution of the matrix-element weighted, orbitally resolved density of states.