Phase diagram, band structure and density of states in two-dimensional attractive Fermi-Hubbard model with Rashba spin-orbit coupling

Abstract

Based on the two-dimensional (2D) attractive Fermi-Hubbard model with Rashba spin-orbit coupling (SOC), the SOC strength and Zeeman field dependencies of the phase diagram are investigated by calculating the pairing gap self-consistently. The results reveal that the phase transition from the BCS superfluid to the topological superfluid occurs under a proper Zeeman field strength and SOC strength. In particular, in contrast to the BCS superfluid, which decreases monotonically as the SOC strength increases, the topological superfluid region shows a dome with increasing SOC strength. An optimal region in the phase diagram for finding the topological superfluid can be found, which is important for experimentally realising the topological superfluid in an optical lattice. Then, we obtain the change in both the band structure and density of states (DOS) during the topological phase transition, and explain the four peaks of DOS in the topological superfluid by the topology change of the lowenergy branch of the quasiparticle energy spectra. Moreover, the topological superfluid could be suppressed by varying the doping concentration.

Exact solutions for a spin-orbit coupled ultracold atom held in a driven double well

“…There have been a great number of research works focusing on novel dynamics of SO-coupled cold atomic systems , for instance, quantum spin dynamics [38,39], spin Josephson dynamics [41][42][43][44] and localization [45,46], Anderson transition of SO-coupled cold atoms [47], collective dynamics [32,48], Bloch oscillation dynamics [50], selective coherent spin transportation [55], spin-dependent dynamic localization [58], controlling stable spin dynamics [59], transparent manipulation of spin dynamics [62], coherent control of spin tunneling [63], and so on. To our knowledge, many works related to the quantum dynamics of SO-coupled cold atomic systems have been studied by applying approximate methods [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61], for instance, numerical simulation [45][46][47][48][49][50], variational approximation [45,…”