Inducing magnetism onto the surface of a topological crystalline insulator

TL;DR

This study demonstrates that placing EuS near SnTe topological crystalline insulator induces magnetism at the interface, breaking time-reversal symmetry and revealing novel quantum effects through magnetotransport measurements.

Contribution

It provides experimental evidence of interface-induced magnetism in SnTe-EuS heterostructures, a novel approach to manipulate topological surface states.

Findings

Hysteretic resistance decrease at the TCI surface

Increased magnetic domain wall density

Hysteretic anomalous Hall effect indicating magnetic canting

Abstract

Inducing magnetism onto a topological crystalline insulator (TCI) has been predicted to result in several novel quantum electromagnetic effects. This is a consequence of the highly strain-sensitive band topology of such symmetry-protected systems. We thus show that placing the TCI surface of SnTe in proximity to EuS, a ferromagnetic insulator, induces magnetism at the interface between SnTe and EuS and thus breaks time-reversal-symmetry in the TCI. Magnetotransport experiments on SnTe-EuS-SnTe trilayer devices reveal a hysteretic lowering of the resistance at the TCI surface that coincides with an increase in the density of magnetic domain walls. This additional conduction could be a signature of topologically-protected surface states within domain walls. Additionally, a hysteretic anomalous Hall effect reveals that the usual in-plane magnetic moment of the EuS layer is canted towards a perpendicular direction at the interface. These results are evidence of induced magnetism at the SnTe-EuS interfaces resulting in broken time-reversal symmetry in the TCI.