Edge physics in two-dimensional topological insulators

TL;DR

This paper reviews the physics of edge states in two-dimensional topological insulators, focusing on their transport properties, the effects of electron interactions, and the emergence of helical Luttinger liquids.

Contribution

It provides a comprehensive review of the theoretical and experimental understanding of edge states and electron interactions in 2D topological insulators, highlighting the helical Luttinger liquid paradigm.

Findings

Edge states exhibit spin-momentum locking protected by time-reversal symmetry.

Electron interactions can induce backscattering, affecting conductance.

Experimental evidence supports the helical Luttinger liquid model.

Abstract

Topology in condensed matter physics manifests itself in the emergence of edge or surface states protected by underlying symmetries. We review two-dimensional topological insulators whose one-dimensional edge states are characterized by spin-momentum locking and protected by time-reversal symmetry. We focus in particular on their transport properties in the presence of electron interactions, which can allow the onset of different backscattering mechanisms, thus leading to deviations from the quantized conductance observed in the ballistic regime. The combined presence of helicity and electron interactions creates a new paradigm of the one-dimensional world called helical Luttinger liquid, whose theoretical properties and experimental observations are reviewed.