Correlation-driven organic 3D topological insulator with relativistic fermions

TL;DR

This paper reports the discovery of a correlation-driven topological insulator in an organic compound, exhibiting a surface Dirac semimetal state and a unique current-induced topological phase switching, expanding the understanding of topological phases driven by electron correlations.

Contribution

It introduces a new organic correlation-driven topological insulator with tunable topological phases and demonstrates its unique transport properties and phase switching capabilities.

Findings

Surface metallic state with Dirac semimetal characteristics

Observation of topological phase switching via dc current

Potential for novel electronic device applications

Abstract

Exploring new topological phenomena and functionalities induced by strong electron correlation has been a central issue in modern condensed-matter physics. One example is a topological insulator (TI) state and its functionality driven by the Coulomb repulsion rather than a spin-orbit coupling. Here, we report a "correlation-driven" TI state realized in an organic zero-gap system $\alpha$-(BETS)$_2$I$_3$. The surface metallic state that emerges at low temperatures exhibits characteristic transport properties of a gapless Dirac semimetal, evidencing the presence of a topological surface state in this compound. Moreover, we observe a topological phase switching between the TI state and non-equilibrium Dirac semimetal state by a dc current, which is a unique functionality of a correlation-driven TI state. Our findings demonstrate that correlation-driven TIs are promising candidates not only for practical electronic devices but also as a field for discovering new topological phenomena and phases.