Three-dimensional spin–orbit coupled Fermi gases: Fulde–Ferrell pairing, Majorana fermions, Weyl fermions, and gapless topological superfluidity*
Liu Xia-Jia), Hu Huia), Pu Hanb),c)†
       
The characteristic quasiparticle excitation spectrum E 2±( kx = 0, k y , kz ) in the gapless topo-FF4 phase with h in = 0.33 E F (a) and in the gapless topo-FF2 phase with h in = 0.40 E F (b). The corresponding contour plots of E 2+( kx = 0, k y , kz ) are shown in panels (c) and (d), respectively. The Weyl nodes are highlighted by yellow solid circles. We note that the out-of-plane Zeeman field h out = 0. The spectrum is symmetric with respect to k y , so we plot only the left part with k y ≤ 0.