Nonlinear Conduction by Melting of Stripe-Type Charge Order in Organic Conductors with Triangular Lattices

TL;DR

This paper presents a theoretical study of nonlinear conduction in organic conductors, showing how bias-induced melting of stripe-type charge order leads to unique current-voltage behavior, aligning with experimental findings.

Contribution

It introduces a nonequilibrium Green's function approach to model charge order melting and reveals the coexistence and selective melting of charge orders under bias.

Findings

Bias melts stripe-type charge order via lattice distortion reduction.

3-fold charge order remains stable under bias.

The model's results match experimental observations.

Abstract

We theoretically discuss the mechanism for the peculiar nonlinear conduction in quasi-two-dimensional organic conductors \theta-(BEDT-TTF)2X [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene] through the melting of stripe-type charge order. An extended Peierls-Hubbard model attached to metallic electrodes is investigated by a nonequilibrium Green's function technique. A novel current-voltage characteristic appears in a coexistent state of stripe-type and nonstripe 3-fold charge orders, where the applied bias melts mainly the stripe-type charge order through the reduction of lattice distortion, whereas the 3-fold charge order survives. These contrastive responses of the two different charge orders are consistent with the experimental observations.