Author(s):

Authors: Yong Xu, Chuanwei Zhang

The experimental observation of traditional Zeeman-field induced

Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids has been hindered by

various challenges, in particular, the requirement of low dimension systems. In

2D, it is well known that finite temperature phase fluctuations lead to

extremely small Berezinskii-Kosterlitz-Thouless (BKT) transition temperature,

raising serious concern regarding the observability of 2D FFLO superfluids.

Recently, it was shown that FFLO superfluids can be realized using a Rashba

spin-orbit coupled Fermi gas subject to Zeeman fields, which may also support

topological excitations such as Majorana fermions in 2D. Here we address the

finite temperature BKT transition issue in this system, which may exhibits

gapped, gapless, topological, and gapless topological FF phases. We find a

large BKT transition temperature due to large effective superfluid densities,

making it possible to observe 2D FF superfluids at finite temperature. In

addition, we show that gapless FF superfluids can be stable due to their

positive superfluid densities. These findings pave the way for the experimental

observation of 2D gapped and gapless FF superfluids and their associated

topological excitations at finite temperature.

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