Non thermal isostructural electrically driven insulator-metal transition and electro-strain in layered cobaltate

TL;DR

This paper reports a novel electrically driven insulator-metal transition and electro-strain in layered cobaltates, characterized by volume expansion and associated with changes in cobalt spin states, observed across multiple scales.

Contribution

It demonstrates a non-thermal, electrically induced IMT and electro-strain in layered cobaltates, a phenomenon not previously observed in temperature-dependent transitions.

Findings

Electrically driven IMT observed in layered cobaltates.

Volume expansion of up to 0.3% during transition.

Growth of metallic regions at macroscopic, microscopic, and atomic scales.

Abstract

We report here a discovery of electrically driven insulator to metal transition (IMT) and concomitant isostructural volume expansion in the layered cobaltates which otherwise do not exhibit temperature dependent IMT. These findings are demonstrated at macroscopic, microscopic and atomic scales. With application of voltage growth of metallic regions have been observed in the 2D layered La2-xSrxCoO4. Growth of metallic regions is associated with volume increase (strain as high as 0.3%). Non thermal IMT and electro-strain are proposed to be caused by electro-proliferation of the Co3+ high spin states.