Single atom anisotropic magnetoresistance on a topological insulator surface

TL;DR

This paper investigates the anisotropic magnetoresistance caused by magnetic adatoms on topological insulator surfaces, combining first-principles calculations and a 2D model to explain experimental discrepancies and propose a device setup.

Contribution

It introduces a comprehensive theoretical framework for understanding single atom anisotropic magnetoresistance on topological insulators, linking electronic structure to spin textures and device applications.

Findings

Demonstrates the origin of anisotropic magnetoresistance from spin-momentum locking and hybridization.

Provides a 2D model applicable to adatoms and clusters, guiding experimental design.

Explains conflicting experimental results through detailed spin texture analysis.

Abstract

We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our first-principles quantum transport calculations based on density functional theory for Mn on Bi$_2$Se$_3$ elucidate the underlying mechanism. We complement our findings with a two dimensional model valid for both single adatoms and magnetic clusters, which leads to a proposed device setup for experimental realization. Our results provide an explanation for the conflicting scattering experiments on magnetic adatoms on topological insulator surfaces, and reveal the real space spin texture around the magnetic impurity.