2013/02/28 by Xiang-Fa Zhou, Guang-Can Guo, Wei Zhang +1 · 1 citation
Physics and Astronomy · #cond-mat.quant-gas
paper · pdf · doi:10.1103/physreva.87.063606
published as Phys. Rev. A 87, 063606 (2013) · 9 pages, 8 figures, replaced with the published version
arxiv created 2013/06/07 · arxiv updated 2013/06/10
We investigate properties of exotic pairing states in a three-dimensional Fermi gas with three-dimensional spin-orbit coupling and an effective Zeeman field. The interplay of spin-orbit coupling, effective Zeeman field and pairing can lead to first-order phase transitions between different phases, and to interesting nodal superfluid states with gapless surfaces in the momentum space. We then demonstrate that pairing states with zero center-of-mass momentum are unstable against finite center-of-mass momentum Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) states, with the center-of-mass momentum of the pairs opposite to the direction of the effective Zeeman field. Unlike conventional FFLO states, these FFLO states are induced by the coexistence of spin-orbit coupling and Fermi surface deformation, and have intriguing features like first-order transitions between different FFLO states, nodal FFLO states with gapless surfaces in momentum space, and exotic fully gapped FFLO states. With the recent theoretical proposals for realizing three-dimensional spin-orbit coupling in ultracold atom gases, our work is helpful for the future experimental studies, and provides valuable information for the general understanding of pairing physics in spin-orbit coupled fermionic systems.