Spin-orbit scattering in quantum diffusion of massive Dirac fermions

TL;DR

This paper investigates how spin-orbit scattering influences quantum diffusion in two-dimensional massive Dirac fermions, revealing its effects on weak localization and proposing experimental detection methods in topological insulator thin films.

Contribution

It provides a detailed analysis of spin-orbit scattering effects on Dirac fermions' quantum diffusion, highlighting differences from conventional electrons and suggesting experimental implications.

Findings

Spin-orbit scattering suppresses weak localization in large-mass Dirac fermions.

Behavior of Cooperons varies from singlet to triplet with mass change.

Experimental detection of weak localization in topological insulators is proposed.

Abstract

Effect of spin-orbit scattering on quantum diffusive transport of two-dimensional massive Dirac fermions is studied by the diagrammatic technique. The quantum diffusion of massive Dirac fermions can be viewed as a singlet Cooperon in the massless limit and a triplet Cooperon in the large-mass limit. The spin-orbit scattering behaves like random magnetic fields only to the triplet Cooperon, and suppresses the weak localization of Dirac fermions in the large-mass regime. This behavior suggests an experiment to detect the weak localization of bulk subbands in topological insulator thin films, in which a narrowing of the cusp of the negative magnetoconductivity is expected after doping heavy-element impurities. Finally, a detailed comparison between the conventional two-dimensional electrons and Dirac fermions is presented for impurities of orthogonal, symplectic, and unitary symmetries.