Exploring Ferromagnetic Behavior in Thin Films of the Altermagnetic Candidate MnTe

MnTe is an altermagnatic candidate known for its relatively large spin splitting (>1 eV). We repot on the molecular beam epitaxy (MBE) growth and magneto-transport characterization of MnTe thin-films. while antiferromagnetic-ordered stoichiometric bulk α-MnTe has a bandgap of ~1.4 eV, our epitaxial MnTe layers on an InP(111) substrate display obvious magnetic hysteresis with a saturation field of up to ~20 T at 0.4 K. Longitudinal magnetoresistance exhibits a butterfly-shaped hysteresis, and transverse magnetoresistance exhibits an anomalous Hall effect. Comprehensive density functional theory (DFT) calculations were performed to systematically investigate the structural origins of the unexpected ferromagnetism. The DFT results indicate that point defects, such as Mn interstitials and Mn antisites, and the MnTe/InP interface, can locally break the antiferromagnetic symmetry and induce a net magnetic moment.