CuMn-V compounds: a transition from semimetal low-temperature to semiconductor high-temperature antiferromagnets

TL;DR

This study combines theoretical predictions and experimental data to explore how CuMn-V compounds transition from semimetal to semiconductor and exhibit high-temperature antiferromagnetism, highlighting the importance of crystal structure.

Contribution

It predicts high-temperature antiferromagnetism in orthorhombic CuMnAs and CuMnP, and demonstrates the electronic transition from semimetal to semiconductor with structural stability.

Findings

Orthorhombic CuMnAs exhibits high Ne9el temperature.

CuMnP is predicted to be a semiconductor.

Experimental results on CuMnAs align with theoretical predictions.

Abstract

We report on a theoretical and experimental study of CuMn-V antiferromagnets. Previous works showed low-temperature antiferomagnetism and semimetal electronic structure of the semi-Heusler CuMnSb. In this paper we present theoretical predictions of high-temperature antiferromagnetism in the stable orthorhombic phases of CuMnAs and CuMnP. The electronic structure of CuMnAs is at the transition from a semimetal to a semiconductor and we predict that CuMnP is a semiconductor. We show that the transition to a semiconductor-like band structure upon introducing the lighter group-V elements is present in both the metastable semi-Heusler and the stable orthorhombic crystal structures. On the other hand, the orthorhombic phase is crucial for the high N\'eel temperature. Results of X-ray diffraction, magnetization, transport, and neutron diffraction measurements we performed on chemically synthesized CuMnAs are consistent with the theory predictions.