Electrostatic gating of metallic and insulating phases in SmNiO3 ultrathin films

TL;DR

This study demonstrates electrostatic control of the metal-insulator transition in ultrathin SmNiO3 films using ionic liquid gating, achieving significant resistance modulation primarily through electrostatic charge accumulation.

Contribution

It provides evidence that resistance changes are mainly due to electrostatic effects rather than electrochemical doping, with quantitative modeling of charge accumulation and capacitance.

Findings

~25% resistance modulation at room temperature

Resistance modulation driven mainly by electrostatic charge accumulation

Estimated sheet density of ~1-2 x 10^14 cm^-2 and EDL capacitance of ~12 μF/cm^2

Abstract

The correlated electron system SmNiO3 exhibits a metal-insulator phase transition at 130 {\deg}C. Using an ionic liquid as an electric double layer (EDL) gate on three-terminal ultrathin SmNiO3 devices, we investigate gate control of the channel resistance and transition temperature. Resistance reduction is observed across both insulating and metallic phases with ~25% modulation at room temperature. We show that resistance modulation is predominantly due to electrostatic charge accumulation and not electrochemical doping by control experiments in inert and air en-vironments. We model the resistance behavior and estimate the accumulated sheet density (~1-2 x 10^14 cm^-2) and EDL capacitance (~12 {\mu}F/cm^2).