# Superfluid-insulator transition and the BEC-BCS crossover in the Rashba moat band

## TL;DR

This paper investigates the superconducting transition in a 2D electron gas with Rashba spin-orbit coupling, revealing a tunable BEC-BCS crossover driven by chemical potential or gate distance.

## Contribution

It demonstrates how the BEC-BCS crossover can be controlled in a Rashba system through chemical potential and Coulomb interactions.

## Key findings

- Superconducting transition follows BEC or BCS depending on chemical potential.
- Crossover can be tuned by gate distance or chemical potential.
- Coulomb repulsion influences the transition regime.

## Abstract

We study the superconducting transition in a two-dimensional electron gas with strong Rashba spin-orbit coupling. We assume low electron density, such that only the majority spin band participates in the transition. We show that the superconducting transition follows either the Bose-Einstein condensation (BEC), or the Bardeen-Cooper-Schrieffer (BCS) scenarios, depending on the position of the chemical potential with respect to the bottom of the majority band, and the strength of the Coulomb repulsion between electrons. Hence, the BEC-BCS crossover in this system can be driven either by the change in the chemical potential, or the distance to a gate.