Chern Insulator Phase in a Lattice of an Organic Dirac Semimetal with Intracellular Potential and Magnetic Modulations

TL;DR

This paper proposes a method to realize a Chern insulator in an organic Dirac semimetal lattice by introducing potential and magnetic modulations, leading to a topologically nontrivial phase with quantum Hall effects at zero magnetic field.

Contribution

It introduces a novel organic lattice model that achieves a Chern insulator phase through specific potential and magnetic modulations, extending Haldane's model to organic materials.

Findings

System becomes a Chern insulator with large magnetic modulation.

Berry curvatures around Dirac cones have the same sign.

Chiral edge states connect conduction and valence bands.

Abstract

We demonstrate that a Chern insulator could be realized on a real two-dimensional lattice of an organic Dirac semimetal {\alpha}-(BEDT-TTF)2I3 by introducing potential and magnetic modulations in a unit cell. It is a topologically-nontrivial insulator which shows the quantum Hall effect even at zero magnetic field. We assumed a pattern of site potential and staggered plaquette magnetic flux on the lattice so as to imitate the observed stripe charge ordering pattern. When the magnetic modulation is sufficiently large, the system becomes a Chern insulator, where Berry curvatures around two gapped Dirac cones have the same sign on each band, and one chiral edge state connects the conduction and valence bands at each crystal edge. The present model is an organic version of Haldane's model, which discussed the Chern insulator on the honeycomb lattice with second nearest neighbor couplings.