Bulk-like magnetic properties in MBE-grown unstrained, antiferromagnetic CuMnSb

TL;DR

This study investigates how molecular beam epitaxy growth conditions affect the structural and magnetic properties of CuMnSb films, revealing that optimal stoichiometry yields bulk-like antiferromagnetic behavior, with thickness-dependent magnetic properties relevant for Néel vector switching.

Contribution

It provides detailed insights into the growth conditions that produce bulk-like magnetic properties in CuMnSb thin films, highlighting the importance of stoichiometry and thickness control.

Findings

Maximum Néel temperature at optimal Mn/Sb flux ratio

Bulk-like magnetic properties achieved in sufficiently thick layers

Thinner layers show reduced Néel temperature

Abstract

A detailed study of the influence of molecular beam epitaxial growth conditions on the structural and magnetic characteristics of CuMnSb films on lattice matched GaSb is presented. For a set of nine 40~nm thick layers, the Mn and Sb fluxes are varied to produce material with different elemental compositions. It is found that the layers grown under a relative Mn to Sb flux ratio of $\Phi_{\text{Mn}}$/$\Phi_{\text{Sb}}=1.24\pm0.02$ are closest to the stoichiometric composition, for which the N\'{e}el temperature ($T_\text{N}$) attains its maximum values. Mn-related structural defects are believed to be the driving contribution to changes in the vertical lattice parameter. Having established the optimum growth conditions, a second set of samples with CuMnSb layer thickness varied from 5 to 510 nm is fabricated. We show that for sufficiently large thicknesses, the magnetic characteristics ($T_\text{N}\simeq62$ K, Curie-Weiss temperature $\Theta_\text{CW} = -100$ K) of the stoichiometric layers do correspond to the parameters reported for bulk samples. On the other hand, we observe a reduction of $T_\text{N}$ as a function of the CuMnSb thickness for our thinnest layers. All findings reported here are of particular relevance for studies aiming at the demonstration of N\'{e}el vector switching and detection in this noncentrosymmetric antiferromagnet, which have been recently proposed.