# Impurity scattering on the surface of topological insulator thin films

## TL;DR

This paper investigates how impurities affect the electronic and magnetic properties of topological insulator surface states, revealing tunable effects via electric fields and implications for magnetic states and transport.

## Contribution

It introduces a detailed analysis of impurity effects on topological insulator surfaces using Green's function methods, including electric field tuning and spin-resolved states.

## Key findings

- Impurities alter local density of states and spin textures.
- Electric fields can tune impurity effects.
- Magnetic impurities influence spin susceptibility.

## Abstract

We address the electronic structure of the surface states of topological insulator thin films with embedded local non-magnetic and magnetic impurities. Using the $T$-matrix expansion of the real space Green's function, we derive the local density of electrons states and corresponding spin resolved densities. We show that the effects of the impurities can be tuned by applying an electric field between the surface layers. The emerging magnetic states are expected to play an important role both in ferromagnetic mechanism of magnetic topological insulators as well as in its transport properties. In the case of magnetic impurities, we have categorized the possible cases for different spin-directions of the impurities as well as the spin-direction in which the spin resolved density of electron states is calculated and related this to the spin susceptibility of the system.