Transport signatures of surface potentials on three-dimensional topological insulators

TL;DR

This paper investigates how surface potentials affect the spin textures of 3D topological insulators and proposes using spin-polarized tunneling to identify and characterize these potentials.

Contribution

It provides a comprehensive study of surface potential effects on 3D TI surface states and introduces a method to detect and quantify these potentials via spin-polarized tunneling.

Findings

Surface potentials distort spin textures without opening a gap.

Spin-polarized tunneling can detect surface potential effects.

Method enables quantitative characterization of surface potentials.

Abstract

The spin-momentum locked nature of the robust surface states of three dimensional topological insulators (3D TI) make them promising candidates for spintronics applications. Surface potentials which respect time reversal symmetry can exist at the surface between a 3D TI and the trivial vacuum. These potentials can distort the spin texture of the surface states while retaining their gapless nature. In this work, the effect of all such surface potentials on the spin textures is studied. Since, a tunnel magnetoresistance signal carries the information of the spin texture, it is proposed that spin-polarized tunneling of electrons to a 3D TI surface can be used to uniquely identify the surface potentials and quantitatively characterize them.