Nonlinear current-voltage behavior and electrically driven phase transition in charge frustrated LuFe2O4

TL;DR

This study reveals that LuFe2O4 exhibits strong nonlinear electric conduction and a current-driven phase transition from charge ordering to a metallic state, with the transition linked to the collapse of charge order under an electric field.

Contribution

It demonstrates the intrinsic link between nonlinear I-V behavior and a charge ordering insulator-metal transition driven by electric field in LuFe2O4, supported by TEM evidence.

Findings

Nonlinear electric conduction observed in LuFe2O4.

Electric field induces charge order collapse and insulator-metal transition.

Threshold fields are about 60V/cm and 10V/cm for different orientations.

Abstract

Electric transport measurements of the charge frustrated LuFe2O4, in which the charge ordering (CO) and electronic ferroelectricity are found, reveal strong nonlinear electric conduction upon application of electrical field in both single crystalline and polycrystalline samples. The threshold electric fields (Et) in single crystalline LuFe2O4 are estimated respectively to be about 60V/cm and 10V/cm with E parallel and perpendicular to the c-axis direction. Experimental measurements also demonstrate that the I-V nonlinearity increases quickly with lowering temperature. Furthermore, our in-situ TEM investigations evidently reveal that the nonlinear I-V behavior is intrinsically in correlation with a current driven charge ordering insulator-metal transition, and the applied electrical field triggers a visible CO collapse recognizable as the fading of satellite spots of the CO modulations.