The stability and physical properties of the tetragonal phase of bulk CuMnAs antiferromagnet

TL;DR

This study investigates how Cu substitution stabilizes the tetragonal phase of CuMnAs and explores its magnetic properties, revealing that small compositional changes enable phase control for potential antiferromagnetic spintronics applications.

Contribution

It demonstrates experimentally and theoretically that Cu substitution stabilizes the tetragonal phase of CuMnAs, enabling phase control for spintronic applications.

Findings

Cu substitution stabilizes the tetragonal phase at x ~ 0.1 or higher.

The tetragonal phase exhibits antiferromagnetic behavior with T_N up to 507 K.

Small compositional variations allow selective growth of different phases.

Abstract

The effect of Cu substitution on the stability of the CuMnAs tetragonal phase was studied both experimentally and by ab initio calculations. Polycrystalline samples with various compositions Cu$_{1+x}$Mn$_{1-x}$As $(x = 0 - 0.5)$ were synthetized. The tetragonal phase of CuMnAs is found to be stabilized by substituting Mn by Cu in the amount of $x$ ~ 0.1 or higher. This observation is supported by ab initio calculations of the total energy of the tetragonal and orthorhombic phases; with increasing Cu content the tetragonal phase is favoured. Small variations of composition thus allow to grow selectively one of these two phases with distinct and unique features for antiferromagnetic spintronics. Measurements of magnetic susceptibility and differential scanning calorimetry have shown that the tetragonal Cu$_{1+x}$Mn$_{1-x}$As has an antiferromagnetic behaviour with the maximum N\'eel temperature $T_N$ = 507 K for the highest Mn content samples, decreasing with the decreasing Mn content.