Scattering times and mobility with localized impurities in topological insulator films

TL;DR

This paper investigates how localized impurities, surface hybridization, and magnetic effects influence scattering times and mobility of Dirac fermions on topological insulator surfaces, highlighting factors that can enhance or suppress surface conductivity.

Contribution

It provides a comparative analysis of different impurity effects and their impact on scattering times and mobility in topological insulator films, including the role of band warping and magnetic impurities.

Findings

Magnetic impurities introduce additional spin suppression.

Surface hybridization affects scattering between opposite helicity states.

Band warping can enhance surface mobility.

Abstract

The zero gap surface states of a 3D-topological insulator host highly mobile Dirac fermions with spin locked to the momentum. The high mobility attributed to absence of back scattering is reduced in presence of impurities on the surface. In particular, we discuss and compare scattering times for localized impurities on the surface, scattering between states of opposite helicity located on different surfaces coupled through a hybridization potential, and the role of magnetic impurities. Magnetic impurities give rise to an additional spin suppression factor. The role of warped bands and its influence on topological factors that can enhance the overall surface mobility is examined.