Emergence of Unconventional Interfacial Magnetic Phenomenon in Topological Insulator-Based Magnetic Heterostructures

TL;DR

This study reveals unconventional interfacial magnetic phenomena in topological insulator/magnetic insulator heterostructures, using planar Hall effect measurements to detect non-trivial in-plane spin textures that are sensitive to magnetic anisotropy.

Contribution

It demonstrates the use of planar Hall effect to identify and characterize non-trivial in-plane spin textures at TI/MI interfaces, especially with in-plane magnetic anisotropy.

Findings

Observation of planar topological Hall effect indicating non-trivial spin textures.

Maximum planar Hall features when current and magnetic field are perpendicular.

Minimum features when current and magnetic field are parallel.

Abstract

In a topological insulator (TI)/magnetic insulator (MI) hetero-structure, large spin-orbit coupling of the TI and inversion symmetry breaking at the interface could foster non-planar spin textures such as skyrmions at the interface. This is observed as topological Hall effect in a conventional Hall set-up. While this effect has been observed at the interface of TI/MI, where MI beholds perpendicular magnetic anisotropy, non-trivial spin-textures that develop in interfacial MI with in-plane magnetic anisotropy is under-reported. In this work, we study Bi$_2$Te$_3$/EuS hetero-structure using planar Hall effect (PHE). We observe planar topological Hall and spontaneous planar Hall features that are characteristic of non-trivial in-plane spin textures at the interface. We find that the latter is minimum when the current and magnetic field directions are aligned parallel, and maximum when they are aligned perpendicularly within the sample plane, which maybe attributed to the underlying planar anisotropy of the spin-texture. These results demonstrate the importance of PHE for sensitive detection and characterization of non-trivial magnetic phase that has evaded exploration in the TI/MI interface.