Phase-Controlled Epitaxy and Anisotropic Antiferromagnetism of Polar Wurtzite MnTe

Altermagnetic spintronics requires materials in which compensated magnetic order, symmetry-controlled electronic responses, and epitaxial tunability can be combined in experimentally accessible thin films. MnTe is a key material in this context, but experimental studies have focused mainly on the stable NiAs-type polymorph, whereas the polar wurtzite phase remains largely unexplored. Here we demonstrate molecular-beam epitaxy growth and investigate properties of nearly phase-pure wurtzite MnTe deposited directly on GaAs(111)B, and show that small changes in the growth conditions strongly modify the phase composition, from a multiphase state with endotaxial NiAs-type inclusions embedded in wurtzite MnTe matrix to an almost single-phase polar wurtzite layer.