Conductivity scaling of the anomalous Hall effect in the altermagnetic semiconductor {\alpha}-MnTe

TL;DR

This study investigates the anomalous Hall effect in { extalpha}-MnTe thin films, revealing a conductivity scaling law consistent with a hopping conduction mechanism and highlighting the material's potential for spintronic applications.

Contribution

It demonstrates that the AHE in { extalpha}-MnTe follows a specific scaling law linked to hopping conduction and clarifies the origin of sample variations, advancing understanding of altermagnetic semiconductors.

Findings

AHE amplitude varies between samples but follows a universal scaling law.

The AHE in { extalpha}-MnTe is colossal compared to its magnetization.

The results suggest a hopping conduction mechanism underlies the AHE.

Abstract

{\alpha}-MnTe is a prototypical altermagnet exhibiting a strong anomalous Hall effect (AHE), despite having a nearly vanishing magnetization. Lately, sample-to-sample variations of the amplitude of the AHE have raised concerns of a possible defect related origin, especially in thin films. Here, we study the AHE in {\alpha}-MnTe films grown on SrF2 that have the crystal structure and m'm'm magnetic point group symmetry expected for bulk. By studying the scaling of the AHE with conductivity for those films and previously reported measurements in the literature, we find that sample-to-sample variations are well explained by a scaling law consistent with a hopping origin. Importantly, a comparison with other magnetic semiconductors reveals the colossal amplitude of the AHE of {\alpha}-MnTe compared to its measured spontaneous magnetization from magnetometry and polarized neutron reflectivity. Our findings address the important fundamental question of the origin of the AHE of {\alpha}-MnTe and further demonstrate the potential of altermagnets as promising spintronic materials.