Mott Physics on Helical Edges of 2D Topological Insulators

TL;DR

This paper investigates how electron correlations induce a Mott transition in the helical edges of 2D topological insulators, revealing a transition from a topological insulator to an edge Mott insulator with a helical spin-liquid phase.

Contribution

It provides the first detailed variational Monte Carlo analysis showing the suppression of edge conduction and the emergence of an edge Mott insulator due to electron correlations.

Findings

Suppression of charge Drude weight with increasing Coulomb interactions

Transition from topological insulator to edge Mott insulator

Presence of a helical spin-liquid phase with preserved time-reversal symmetry

Abstract

We study roles of electron correlations on topological insulators on the honeycomb lattice with the spin-orbit interaction. Accurate variational Monte Carlo calculations show that the increasing on-site Coulomb interactions cause a strong suppression of the charge Drude weight in the helical-edge metallic states leading to a presumable Mott transition from a conventional topological insulator to an edge Mott insulator before a transition to a bulk antiferromagnetic insulator. The intermediate bulk-topological and edge-Mott-insulator phase has a helical spin-liquid character with the protected time-reversal symmetry.