Rotating a Rashba-coupled Fermi gas in two dimensions

TL;DR

This paper investigates how adiabatic rotation and Rashba spin-orbit coupling influence the BCS-BEC crossover in a two-dimensional trapped Fermi gas, revealing conditions for annulus formation and coexistence phases.

Contribution

It introduces a combined analysis of rotation and spin-orbit coupling effects on superfluid phases in 2D Fermi gases, including both semi-classical and quantum approaches.

Findings

Formation of ring-shaped annulus in non-interacting gas.

Identification of a coexistence phase with superfluid and normal particles.

Conditions for creating isolated rotating normal annulus or intermediate gapless superfluid.

Abstract

We analyze the interplay of adiabatic rotation and Rashba spin-orbit coupling on the BCS-BEC evolution of a harmonically-trapped Fermi gas in two dimensions under the assumption that vortices are not excited. First, by taking the trapping potential into account via both the semi-classical and exact quantum-mechanical approaches, we firmly establish the parameter regime where the non-interacting gas forms a ring-shaped annulus. Then, by taking the interactions into account via the BCS mean-field approximation, we study the pair-breaking mechanism that is induced by rotation, i.e., the Coriolis effects. In particular, we show that the interplay allows for the possibility of creating either an isolated annulus of rigidly-rotating normal particles that is disconnected from the central core of non-rotating superfluid pairs or an intermediate mediator phase where the superfluid pairs and normal particles coexist as a partially-rotating gapless superfluid.