# Ferromagnetic phase transition in topological crystalline insulator thin films: interplay of anomalous Hall angle and magnetic anisotropy

## TL;DR

This paper reports on the observation of ferromagnetic phase transition and anomalous Hall effects in Mn-doped SnTe thin films, highlighting their potential for realizing quantum anomalous Hall states in topological crystalline insulators.

## Contribution

It demonstrates ferromagnetism with perpendicular anisotropy and large anomalous Hall angles in Mn-doped SnTe films, advancing the understanding of magnetic topological phases.

## Key findings

- Ferromagnetism observed in Sn$_{1-x}$Mn$_{x}$Te with $x\,geq0.06$
- Highest $T_c$ of ~7.5 K in Sn$_{0.92}$Mn$_{0.08}$Te
- Large anomalous Hall angle of ~0.3 in the material

## Abstract

In magnetic topological phases of matter, the quantum anomalous Hall (QAH) effect is an emergent phenomenon driven by ferromagnetic doping, magnetic proximity effects and strain engineering. The realization of QAH states with multiple dissipationless edge and surface conduction channels defined by a Chern number $\mathcal{C}\geq1$ was foreseen for the ferromagnetically ordered SnTe class of topological crystalline insulators (TCIs). From magnetotransport measurements on Sn$_{1-x}$Mn$_{x}$Te ($0.00\leq{x}\leq{0.08}$)(111) epitaxial thin films grown by molecular beam epitaxy on BaF$_{2}$ substrates, hole mediated ferromagnetism is observed in samples with $x\geq0.06$ and the highest $T_\mathrm{c}\sim7.5\,\mathrm{K}$ is inferred from an anomalous Hall behavior in Sn$_{0.92}$Mn$_{0.08}$Te. The sizable anomalous Hall angle $\sim$0.3 obtained for Sn$_{0.92}$Mn$_{0.08}$Te is one of the greatest reported for magnetic topological materials. The ferromagnetic ordering with perpendicular magnetic anisotropy, complemented by the inception of anomalous Hall effect in the Sn$_{1-x}$Mn$_{x}$Te layers for a thickness commensurate with the decay length of the top and bottom surface states, points at Sn$_{1-x}$Mn$_{x}$Te as a preferential platform for the realization of QAH states in ferromagnetic TCIs.