Manipulation of the Anomalous Hall Effect in Altermagnetic MnTe Thin Films

In altermagnets, the combination of zero net magnetization and features such as the anomalous Hall effect (AHE) and polarized spin currents make them ideal candidates for spintronics devices.¹ Recent studies realized this AHE in thin films of semiconducting α-MnTe grown on lattice-matched InP.^2,3 In light of these results, the role of point defects and strain remains elusive and warrants further investigation. To clarify the intrinsic material parameters underpinning the AHE, we study α-MnTe grown on both GaAs and SrF₂ and achieve substrate-dependent tuning of the AHE in AM MnTe with field cooling.⁴ We report the synthesis of single-phase MnTe films by MBE and magnetotransport as a function of in-plane field cooling strength. In MnTe on SrF₂, we observe a spontaneous AHE (0.09μΩm) at low temperatures (2K), which is insensitive to field cooling and agrees with the expected intrinsic AM origin. In MnTe on GaAs, field cooling tunes the size and polarity of the AHE (0.02-0.1 μΩm). This tunable behavior deviates from predictions based on the symmetry allowed AHE. We suggest substrate-induced strain as a potential origin for this deviation, considering recent DFT calculations predicting that strain can influence the location of the valence band edge in MnTe.⁵ Overall, this work provides a timely perspective of extrinsic and intrinsic effects tying the substrate to the emergence of a tunable AHE in MnTe.

PhysRevX 12(4) 040501

Phys Rev Lett 130(3) 03670

Adv Funct Mater 2405829

arXiv:2409.04567

PhysRevB 107(10) L100417