Topological Insulator State due to Finite Spin-Orbit Interaction in an Organic Dirac Fermion System

TL;DR

This paper demonstrates that a finite spin-orbit interaction in an organic Dirac fermion system can induce a topological insulator state, providing a theoretical model analogous to the Kane-Mele model for graphene.

Contribution

It introduces a lattice model with plausible spin-orbit coupling showing that organic Dirac systems can host topological insulator states.

Findings

The model predicts a topological insulator phase due to spin-orbit interaction.

The organic analogue of the Kane-Mele model is proposed.

The gapped state explains the insulating behavior in alpha-(BEDT-TTF)2I3.

Abstract

Recently, Valenti et al. pointed out the significance of the spin-orbit interaction (SOI) in organic materials, and explained the anomalous insulating behavior of a Dirac semimetal alpha-(BEDT-TTF)2I3 at low temperatures in terms of the small SOI gap. We propose a lattice model with plausible SOI coupling, and indicate that the gapped state is a topological insulator. This model is an organic analogue of the Kane-Mele model for graphene.