Pairing Symmetry, Phase diagram and Edge Modes in Topological Fulde-Ferrell-Larkin-Ovchinnikov Phase

TL;DR

This paper explores the pairing symmetry, phase diagram, and edge modes in topological Fulde-Ferrell-Larkin-Ovchinnikov superfluids realized in spin-orbit coupled cold atom systems, revealing unique topological properties and finite size effects.

Contribution

It provides a comprehensive analysis of the pairing symmetry, phase diagram, and edge modes in topological FFLO superfluids with spin-orbit coupling, highlighting novel features not seen in solid materials.

Findings

Asymmetry in effective p-wave pairing due to Zeeman field and finite momentum

Distinct finite size effects in gapped and gapless topological FFLO phases

Identification of different topological phases based on band gap and topology

Abstract

The realizations of spin-orbit coupling in cold atoms lead to a burst of research activities in the searching of topological matters in ultracold atom systems. The very recent theoretical predictions show that topological Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids can be realized with proper spin-orbit coupling and Zeeman fields. In this work, a comprehensive understanding of the pairing symmetry, phase diagram and the edge modes in this new topological matter are presented. The momentum of the Cooper pairs plays the role of renormalizing the in-plane Zeeman field and chemical potential. The in-plane Zeeman field and finite momentum pairing induce asymmetry to the effective $p$-wave pairing, apart from a small fraction of higher orbital components. The phase diagram is composed by different phases, which are determined by the topology and band gap nature of the superfluids. Especially, the gapped and gapless topological FFLO phase have totally different finite size effect. These novel features show that the spin-orbit coupled cold atoms provides an important platform in realizing topological matters which may not be materialized with solids.