Large Spin Splitting and Robust Anomalous Hall effect in Altermagentic MnTe on GaAs(111)

Altermagnetism is a recently discovered magnetic order characterized by non-relativistic alternating spin splitting and collinear magnetic moments. Hexagonal MnTe (i.e., α-MnTe) is a prototypical altermagnet, exhibiting antiparallel spin orientations and band splitting arising from broken time-reversal symmetry. In this work, we employ molecular beam epitaxy (MBE) to grow MnTe thin films on GaAs(111) and perform systematic angle-resolved photoemission spectroscopy (ARPES) measurements. Compared to MnTe films on InP(111) in prior studies, we observe an enhanced lifting of Kramers degeneracy in MnTe films on GaAs(111). Electrical transport measurements reveal square anomalous Hall (AH) hysteresis loops, with AH resistance monotonically increasing as temperature decreases, while superconducting quantum interference device (SQUID) magnetometry confirms a negligible net magnetization in both in-plane and out-of-plane directions. By combining transmission electron microscopy and reciprocal-space mapping analysis, we attribute the observed ferromagnetic-like AH effect to epitaxial strain-induced modifications of the electronic structure. These results advance the understanding of spin splitting and the AH effect in altermagnetic materials and establish MnTe thin films on GaAs(111) as a promising platform for future spintronic applications.