Cooperative dynamics in charge-ordered state of alpha-(BEDT-TTF)2I3

TL;DR

This paper investigates how electric fields influence the charge-ordered state of alpha-(BEDT-TTF)2I3, revealing negative differential resistance and transient states linked to domain-wall dynamics in a ferroelectric-like density wave.

Contribution

It provides experimental evidence of electric-field-induced switching and domain-wall dynamics in a two-dimensional bond-charge density wave system.

Findings

Negative differential resistance observed at fields above 50 V/cm.

Resistance drops to metallic values under high electric fields.

Transient states relax exponentially back to steady state.

Abstract

Electric-field-dependent pulse measurements are reported in the charge-ordered state of alpha-(BEDT-TTF)2I3. At low electric fields up to about 50 V/cm only negligible deviations from Ohmic behavior can be identified with no threshold field. At larger electric fields and up to about 100 V/cm a reproducible negative differential resistance is observed with a significant change in shape of the measured resistivity in time. These changes critically depend whether constant voltage or constant current is applied to the single crystal. At high enough electric fields the resistance displays a dramatic drop down to metallic values and relaxes subsequently in a single-exponential manner to its low-field steady-state value. We argue that such an electric-field induced negative differential resistance and switching to transient states are fingerprints of cooperative domain-wall dynamics inherent to two-dimensional bond-charge density wave with ferroelectric-like nature.