Quantum disorder boosts superconductivity in 2D materials with ionic liquids

Researchers at the Dipartimento di Fisica, Universitá di Trento, and Graphene Labs, Fondazione Istituto Italiano di Tecnologia, have uncovered a link between disorder and superconductivity in two-dimensional materials. Their study reveals that methods used to manipulate charge in these materials inadvertently increase disorder, specifically through an Anderson transition, rather than merely controlling electron flow.

This induced disorder enhances repulsive Coulomb interactions, suppressing the critical temperature and forming a dome-shaped region of enhanced superconductivity. The findings provide a theoretical framework for understanding this phenomenon, which has been a challenging problem in the field.

Frozen ionic liquids push quasi-two-dimensional materials toward an Anderson transition, increasing disorder instead of just modulating charge. This challenges conventional expectations, as these liquids are typically used for precise charge control. The research highlights this effect in gated materials, showing a link between disorder and superconductivity.

Quenched charge fluctuations and reduced screening, resulting from the induced disorder, enhance repulsive Coulomb interactions, suppressing the critical temperature. This finding is counterintuitive, as increased Coulomb repulsion generally inhibits superconductivity. However, the study shows this repulsion shapes the superconducting dome observed in materials like cuprates, nickelates, twisted bilayer graphene, and transition metal dichalcogenides.

By integrating a many-body approach with first-principles calculations, the team achieved quantitative agreement with experimental results for gated few-layer transition metal dichalcogenides at high bias. This study establishes a mechanism for the formation of the superconducting dome, identifying it as a natural outcome of disorder-driven enhancement of Coulomb repulsion.

First-principles calculations, combined with a many-body approach accounting for disorder, now match experimental phase diagrams and tunneling spectra observed in gated few-layer transition metal dichalcogenides. This agreement validates the computational framework used to explore these materials under applied electric fields, offering a new tool for materials prediction and design.

The calculations reveal that disorder-driven enhancement of Coulomb repulsion is a fundamental characteristic of quasi-2D materials gated with ionic liquids at high bias, challenging conventional understanding of gating mechanisms. Specifically, the work identifies that the superconducting dome arises as a natural consequence of increased Coulomb repulsion induced by disorder.

This departs from traditional models where superconductivity is associated with reduced Coulomb interactions and enhanced screening. It provides a theoretical basis for observations made by Morpurgo and colleagues regarding gate-induced superconductivity in atomically thin MoS₂ crystals. Calculations utilized the QUANTUM ESPRESSO software project, alongside a generalized gradient approximation developed by Ernzerhof to model electron behavior.

The team's approach incorporates the mathematical analysis of the multiband BCS gap equations, as outlined by Yang, to describe the superconducting state. It accounts for the velocity, momentum, and position matrix elements for Bloch states using methods detailed by Esteve-Paredes and Palacios, confirming the model's validity and potential for predicting behavior in similar materials.

The team's calculations reveal that the established mechanism extends to multiple material classes, suggesting a broadly applicable principle governing superconductivity in these systems. The findings, published on September 14, 2026, offer a new perspective on manipulating materials to achieve higher-temperature superconductivity.

Previous theoretical frameworks often linked superconductivity to reduced Coulomb interactions, but this work presents a contrasting picture, showing how increased repulsion can actively contribute to the formation and characteristics of the superconducting dome. This dome, previously observed in materials like cuprates and nickelates, is now understood as a natural consequence of the interplay between disorder and Coulomb forces.

Building on earlier work by Gor’kov and Finkel’stein regarding superconductivity in disordered systems, the findings offer a potential explanation for a long-standing challenge in the field, providing a more complete picture of how to manipulate materials for enhanced superconducting properties.