Correlated Zak insulator in organic antiferromagnets

TL;DR

This paper proposes a new type of topological insulator called Zak insulator, realized in organic antiferromagnetic Mott insulators without relying on spin-orbit coupling, and demonstrates its robustness against electron correlations.

Contribution

It introduces a novel topological state called the Zak insulator in strongly correlated organic antiferromagnets, independent of spin-orbit coupling effects.

Findings

Zak insulator characterized by quantized Zak phase is realized in organic antiferromagnets.

The Zak insulator exhibits a large charge gap governed by Coulomb interactions.

The topological state remains stable under electron correlation effects, confirmed by many-body Zak phase calculations.

Abstract

Searching for topological insulators in solids is one of the main issues of modern condensed matter physics since robust gapless edge or surface states of the topological insulators can be used as building blocks of next-generation devices. Enhancing spin-orbit couplings is a promising way to realize topological insulators in solids, whereas the amplitude of the spin-orbit couplings is not sufficiently large in most materials. Here we show a way to realize a topological state characterized by the quantized Zak phase, termed the Zak insulator, with spin-polarized edges in organic antiferromagnetic Mott insulators without relying on the spin-orbit coupling. The obtained Zak insulator can have a large charge gap compared to the conventional topological insulators, since Coulomb interactions mainly govern the amplitude of the charge gap in the antiferromagnetic Mott insulators. Besides the mean-field analysis, we demonstrate that the Zak insulator survives against electron correlation effects by calculating the many-body Zak phase. Our finding provides an unprecedented way to realize a topological state in strongly correlated electron systems.