Observation of chiral currents at the magnetic domain boundary of a topological insulator

TL;DR

This study demonstrates the existence of chiral edge currents at magnetic domain boundaries on a topological insulator surface using advanced magnetic sensing techniques, highlighting potential applications in quantum information and spintronics.

Contribution

We provide direct experimental evidence of chiral edge currents at magnetic domain boundaries in a topological insulator heterostructure, advancing understanding of topological magnetoelectric effects.

Findings

Chiral edge currents are observed at magnetic domain boundaries.

The current's chirality depends on the magnetization of the domain.

The current magnitude is influenced by local chemical potential.

Abstract

A magnetic domain boundary on the surface of a three-dimensional topological insulator is predicted to host a chiral edge state, but direct demonstration is challenging. Here, we used a scanning superconducting quantum interference device to show that current in a magnetized EuS/Bi2Se3 heterostructure flows at the edge when the Fermi level is gate-tuned to the surface band gap. We further induced micron-scale magnetic structures on the heterostructure, and detected a chiral edge current at the magnetic domain boundary. The chirality of the current was determined by magnetization of the surrounding domain and its magnitude by the local chemical potential rather than the applied current. Such magnetic structures, provide a platform for detecting topological magnetoelectric effects and may enable progress in quantum information processing and spintronics.