Disorder-Driven Enhancement of Coulomb Repulsion Governs The Superconducting Dome in Ionic-Liquid-Gated Quasi-2D Materials

TL;DR

This paper shows that disorder from ionic liquids enhances Coulomb repulsion in quasi-2D materials, explaining the superconducting dome without invoking unconventional pairing mechanisms.

Contribution

It introduces a disorder-driven mechanism for the superconducting dome in ionic-liquid-gated quasi-2D materials, supported by combined many-body and first-principles calculations.

Findings

Disorder from ionic liquids drives systems near Anderson transition.

Enhanced Coulomb repulsion suppresses Tc, forming a dome.

Theoretical phase diagrams match experimental data.

Abstract

The superconducting dome in the Tc versus doping phase diagram, found in cuprates, nickelates, twisted bilayer graphene, and transition metal dichalcogenides, is often considered a signature of unconventional pairing. Identifying the underlying mechanisms of any of these phase diagrams and developing a reliable theoretical understanding of it remains a critical challenge. Here we demonstrate that, in ionic-liquid-gated quasi-2D materials, the disordered ionic potential from the frozen ionic liquid drives the system close to Anderson transition. In this regime, quenched charge fluctuations and reduced screening markedly enhance repulsive Coulomb interactions, suppressing Tc and naturally leading to the formation of a superconducting dome. By integrating a many-body approach including disorder with first-principles calculations, we obtain the phase diagrams and tunneling spectra of gated few-layers transition metal dichalchogenides in robust quantitative agreement with experiments. Our findings establish that disorder-driven enhancement of Coulomb repulsion is a fundamental feature of ionic-liquid-gated quasi-2D materials at high bias.