Effects of charge dopants in quantum spin Hall materials

TL;DR

This paper investigates how charge dopants influence the properties of quantum spin Hall materials, revealing their role in topological phase transitions and transport phenomena in two-dimensional topological semiconductors.

Contribution

It provides a quantitative analysis of paramagnetic acceptor dopants' effects on topological semiconductors, introducing new explanations for observed transport and magnetic properties.

Findings

Charge dopants affect topological protection length.

High hole mobilities are linked to dopant interactions.

Temperature dependence of spin Hall resistance varies with doping.

Abstract

Semiconductors' sensitivity to electrostatic gating and doping accounts for their widespread use in information communication and new energy technologies. It is demonstrated quantitatively and with no adjustable parameters that the presence of paramagnetic acceptor dopants elucidates a variety of hitherto puzzling properties of two-dimensional topological semiconductors at the topological phase transition and in the regime of the quantum spin Hall effect. The concepts of charge correlation, Coulomb gap, exchange interaction between conducting electrons and holes localized on acceptors, strong coupling limit of the Kondo effect, and bound magnetic polaron explain a short topological protection length, high hole mobilities compared with electron mobilities, and different temperature dependence of the spin Hall resistance in HgTe and (Hg,Mn)Te quantum wells.