Quantum disorder boosts superconductivity in 2D materials with ionic liquids

Researchers at Dipartimento di Fisica, Universitá di Trento and Graphene Labs, Fondazione Istituto Italiano di Tecnologia have demonstrated a surprising link between disorder and superconductivity in two-dimensional materials. The work reveals that methods used to manipulate charge in these materials unexpectedly drive the system toward increased disorder, specifically an Anderson transition, rather than simply controlling electron flow.

This induced disorder markedly enhances repulsive Coulomb interactions, suppressing the critical temperature and naturally forming a dome-shaped region of enhanced superconductivity. The findings establish a mechanism for this dome, offering a theoretical understanding of a previously challenging problem in the field.

Disorder and Coulomb Repulsion Drive Superconductivity in 2D Materials

Frozen ionic liquids drive quasi-two-dimensional materials toward an Anderson transition, a state of increased disorder, rather than simply modulating charge as previously understood. This behavior challenges conventional expectations, as these liquids are typically employed for precise charge control, not for intentionally introducing disorder into a system. The research demonstrates this effect through the study of gated materials, revealing a surprising link between disorder and the emergence of superconductivity.

Quenched charge fluctuations and reduced screening, consequences of the induced disorder, markedly enhance repulsive Coulomb interactions, ultimately suppressing the critical temperature, T_c. This finding is counterintuitive because increased Coulomb repulsion generally inhibits superconductivity; however, the work shows this repulsion actively 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. The study establishes a mechanism for the formation of the superconducting dome, identifying it as a natural outcome of disorder-driven enhancement of Coulomb repulsion. The findings suggest that controlling disorder, rather than simply minimizing it, could be a key strategy for optimizing superconductivity in these materials, offering a potential pathway for future materials design and applications.

First-Principles Calculations Model Ionic-Liquid-Gated Dichalcogenides

First-principles calculations, combined with a many-body approach accounting for disorder, now quantitatively match experimental phase diagrams and tunneling spectra observed in gated few-layer transition metal dichalcogenides. This level of agreement validates the computational framework used to explore the behavior of 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, a finding that challenges conventional understanding of gating mechanisms. Specifically, the work identifies that the superconducting dome, a region of enhanced superconductivity as a function of carrier density, arises as a natural consequence of increased Coulomb repulsion induced by disorder.

This is a departure from traditional models where superconductivity is often associated with reduced Coulomb interactions and enhanced screening, and 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, a modular and open-source tool for quantum simulations, alongside a generalized gradient approximation developed by Ernzerhof to accurately 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, and accounts for the velocity, momentum, and position matrix elements for Bloch states using the methods detailed by Esteve-Paredes and Palacios, confirming the validity of the model and its 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.

Anderson Transition Regime Impacts Superconducting Properties at High Bias

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.

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