Gating-Induced Mott Transition in NiS$_2$

TL;DR

This paper theoretically investigates the filling-controlled Mott transition in NiS₂ induced by electrolyte gating, revealing a transition at modest electron doping and contrasting spectral coherence with bandwidth control.

Contribution

It introduces a combined DFT+DMFT approach to study gating-induced Mott transitions, providing phase diagrams and spectral insights.

Findings

Mott transition occurs at modest electron doping levels

Gating induces significant incoherent spectral weight at the Fermi level

Contrast between gating and bandwidth control in spectral coherence

Abstract

NiS$_2$ has been widely regarded as a model system to study the bandwidth-controlled Mott transition, as enabled by isovalent Se chemical substitution on the S sites. Motivated by advances in electrolyte gating, we theoretically investigate the filling-controlled Mott transition induced by gating, which has the advantage of avoiding dopant disorder and stoichiometric changes. We use combined Density Functional Theory (DFT) and Dynamical Mean Field Theory (DMFT) to study such a filling-controlled transition and compare it with the case of bandwidth control. We draw a temperature-filling phase diagram and find that the Mott-insulator to metal transition occurs with modest added electron concentrations, well within the capabilities of existing electrolyte gating experiments. We find that there is significant incoherent weight at the Fermi level in the metallic phase when the transition is induced by gating. In contrast, the spectral weight remains rather coherent in the case of the bandwidth-controlled transition.