The Mechanism of Electrolyte Gating on High-Tc Cuprates: The Role of Oxygen Migration and Electrostatics

TL;DR

This study clarifies the mechanisms of electrolyte gating in high-Tc cuprates, showing oxygen migration dominates in NBCO while electrostatics are key in PCCO, resolving previous controversies.

Contribution

It reveals that electrolyte gating mechanisms vary between materials, with oxygen migration being dominant in NBCO and electrostatic effects in PCCO, based on their structural differences.

Findings

Oxygen migration dominates in NBCO gating.

Electrostatic effects are primary in PCCO gating.

Material structure influences gating mechanism.

Abstract

Electrolyte gating is widely used to induce large carrier density modulation on solid surfaces to explore various properties. Most of past works have attributed the charge modulation to electrostatic field effect. However, some recent reports have argued that the electrolyte gating effect in VO2, TiO2 and SrTiO3 originated from field-induced oxygen vacancy formation. This gives rise to a controversy about the gating mechanism, and it is therefore vital to reveal the relationship between the role of electrolyte gating and the intrinsic properties of materials. Here, we report entirely different mechanisms of electrolyte gating on two high-Tc cuprates, NdBa2Cu3O7-{\delta} (NBCO) and Pr2-xCexCuO4 (PCCO), with different crystal structures. We show that field-induced oxygen vacancy formation in CuO chains of NBCO plays the dominant role while it is mainly an electrostatic field effect in the case of PCCO. The possible reason is that NBCO has mobile oxygen in CuO chains while PCCO does not. Our study helps clarify the controversy relating to the mechanism of electrolyte gating, leading to a better understanding of the role of oxygen electro migration which is very material specific.