Symmetry of the tunable anomalous Hall effect in altermagnetic MnTe thin films

Among the predicted altermagnetic materials, α-MnTe is the most widely studied to date, and its anomalous Hall effect (AHE) has been obsserved in bulk and thin films grown on InP [1-3]. In this work, we report the synthesis and magnetotransport of MnTe grown on GaAs [4]. Unlike previous reports of the AHE in MnTe, where the anomalous Hall effect is always allowed by symmetry, we observe that in-plane field cooling (B_FC) is required to activate an AHE in MnTe on GaAs. By probing different in-plane field cooling directions, we identify that the AHE exhibits a 2-fold symmetric behavior with respect to the B_FC direction. Spectroscopy experiments reveal such a symmetry-lowering in MnTe grown on GaAs, which can explain why the AHE vanishes without field cooling. We hypothesize that magnetostriction is effective at restoring the presence of the AHE through in-plane field cooling. Overall, this work emphasizes the subtle yet vital role that epitaxy can play in the properties of altermagnets.

[1] Kreigner, et al. Phys Rev Lett 130, 036702 (2023)

[2] Chilcote, et al. Adv Funct Mater, 2405829 (2024)

[3] Kluczyk, et al. Phys Rev B 110, 155201 (2024)

[4] Bey, et al. Phys. Rev. Mater., 9, 7, 074404 (2025)