BCS-BEC crossover of Spin Polarized Fermi Gases with Rashba Spin-Orbit Coupling

TL;DR

This paper investigates how Rashba spin-orbit coupling influences the BCS-BEC crossover in spin-polarized Fermi gases, revealing that SOC can stabilize polarized superfluid states by balancing pairing effects.

Contribution

It introduces a finite-temperature analysis of the BCS-BEC crossover with SOC, considering pair fluctuations and pseudogap phenomena, which was not extensively studied before.

Findings

SOC enhances pairing, counteracting population imbalance effects

Polarized superfluid states are stabilized over a wide parameter range

Pseudogap persists above the critical temperature T_c

Abstract

We study the BCS-Bose Einstein Condensation (BEC) crossover of a three dimensional spin polarized Fermi gas with Rashba spin-orbital-coupling (SOC). At finite temperature, the effects of non-condensed pairs due to the thermal excitation are considered based on the $G_0G$ pair fluctuation theory. These fluctuations generate a pseudogap even persistent above $T_c$. Within this framework, the Sarma state or the spin polarized superfluid state and polarized pseudogap state are explored in detail. The resulting $T_c$ curves show that the enhancement of pairing due to the SOC roughly cancels out the suppression of pairing due to the population imbalance. Thus we observed that in a large portion of the parameter space, the polarized superfluid state are stabilized by the SOC.