Multiple scattering theory of quasiparticles on a topological insulator surface

TL;DR

This paper develops a multiple scattering theory for quasiparticles on topological insulator surfaces, revealing new scattering features such as backscattering in gapped systems and resonance peaks that can help determine the energy gap.

Contribution

It introduces a partial-wave multiple scattering framework for TI surfaces, highlighting effects of mass gaps and interference in quasiparticle scattering.

Findings

Backscattering occurs for massive Dirac fermions on gapped TI surfaces.

A sharp resonance peak at the band edge can determine the energy gap.

Interference effects and higher partial waves introduce additional resonance peaks.

Abstract

A general partial-wave multiple scattering theory for scattering from cylindrically symmetric potentials on a topological insulator (TI) surface is developed. As an application, the cross sections for a single scatterer and two scatterers are discussed. We find that the symmetry of differential cross section is reduced and the backscattering is allowed for massive Dirac fermions on gapped TI surface. Remarkably, a sharp resonance peak at the band edge of the gapped TI is found in the total cross section $\Lambda_{tot}$, which may offer a useful way to determine the gap (as well as the effective mass of quasiparticles) on TI surface. We show that the interference effect is obvious in cross sections during the quasiparticle scattering between the scatterer pair, and additional resonance peaks are introduced in $\Lambda_{tot}$ when the higher partial waves are taken into account.