Observation of nonlinear planar Hall effect in magnetic insulator/topological insulator heterostructures

TL;DR

This study reports the observation of a significant nonlinear planar Hall effect in magnetic insulator/topological insulator heterostructures, providing a new transport signature for magnetic proximity effects in these systems.

Contribution

It demonstrates the existence of a nonlinear planar Hall effect in Bi2Se3 on magnetic insulators, linking it to magnetic proximity effects and surface state modifications.

Findings

NPHE magnitude is larger on magnetic substrates than nonmagnetic.

NPHE depends linearly on magnetic field in TmIG/Bi2Se3.

YIG/Bi2Se3 shows hysteresis around zero field.

Abstract

Interfacing topological insulators (TIs) with magnetic insulators (MIs) has been widely used to study the interaction between topological surface states and magnetism. Previous transport studies typically interpret the suppression of weak antilocalization or appearance of the anomalous Hall effect as signatures of magnetic proximity effect (MPE) imposed to TIs. Here, we report the observation of nonlinear planar Hall effect (NPHE) in Bi2Se3 films grown on MI thulium and yttrium iron garnet (TmIG and YIG) substrates, which is an order of magnitude larger than that in Bi2Se3 grown on nonmagnetic gadolinium gallium garnet (GGG) substrate. The nonlinear Hall resistance in TmIG/Bi2Se3 depends linearly on the external magnetic field, while that in YIG/Bi2Se3 exhibits an extra hysteresis loop around zero field. The magnitude of the NPHE is found to scale inversely with carrier density. We speculate the observed NPHE is related to the MPE-induced exchange gap opening and out-of-plane spin textures in the TI surface states, which may be used as an alternative transport signature of the MPE in MI/TI heterostructures.