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

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 $ΦMn$/$ΦSb=1.24±0.02$ are closest to the stoichiometric composition for which the Néel temperature (⁠$TN$⁠) 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 (⁠$TN≃62K$⁠, Curie–Weiss temperature $ΘCW=−100$ K) of the stoichiometric layers do correspond to the parameters reported for bulk samples. On the other hand, we observe a reduction of $TN$ 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 Néel vector switching and detection in this noncentrosymmetric antiferromagnet, which have been recently proposed.