Unconventional superfluidity induced by spin-orbital coupling in a polarized two-dimensional Fermi gas

TL;DR

This paper demonstrates that spin-orbital coupling in a 2D polarized Fermi gas can restore superfluidity suppressed by imbalance, leading to unconventional states with potential topological Majorana excitations, and maps the phase diagram at zero temperature.

Contribution

It introduces a method to induce and analyze unconventional superfluid states via artificial gauge fields in 2D Fermi gases, revealing new topological phases and phase transitions.

Findings

Spin-orbital coupling restores superfluidity in imbalanced 2D Fermi gases.

Unconventional superfluid states with topological and mixed pairing are predicted.

Phase transitions can be detected through in-situ density profile measurements.

Abstract

We show the spin-orbital coupling induced by an artificial light-induced gauge field can fully restore superfluidity suppressed by population imbalance in a two-dimensional (2D) Fermi gas, leading to unconventional superfluid states either with topological Majorana fermion excitations or showing a novel mixture of triplet pairing with spin-up (down) components respectively in the $p_{x}\pm ip_{y}$ pairing channels. We self-consistently calculate the zero temperature phase diagram at the BCS\ side of Feshbach resonance and show that the phase transitions between different superfluid states can be revealed through measurement of the in-situ density profile of the 2D atomic cloud in a weak global trap.