A Simple Mechanism for Unconventional Superconductivity in a Repulsive Fermion Model

TL;DR

This paper introduces a simple, analytically tractable lattice model demonstrating unconventional superconductivity driven by strong repulsive interactions, with insights into pairing mechanisms and pseudo-gap phenomena.

Contribution

It presents a novel lattice model that exhibits unconventional superconductivity from repulsive interactions, bridging strong coupling analysis with pseudo-gap physics.

Findings

Model exhibits superconductivity beyond BCS theory.

Strong coupling limit reduces to a Bose-Hubbard model.

Pseudo-gap behavior persists above critical temperature.

Abstract

Motivated by a scarcity of simple and analytically tractable models of superconductivity from strong repulsive interactions, we introduce a simple tight-binding lattice model of fermions with repulsive interactions that exhibits unconventional superconductivity (beyond BCS theory). The model resembles an idealized conductor-dielectric-conductor trilayer. The Cooper pair consists of electrons on opposite sides of the dielectric, which mediates the attraction. In the strong coupling limit, we use degenerate perturbation theory to show that the model reduces to a superconducting hard-core Bose-Hubbard model. Above the superconducting critical temperature, an analog of pseudo-gap physics results where the fermions remain Cooper paired with a large single-particle energy gap.