Wednesday, April 10, 2013

1304.2690 (Zeng-Qiang Yu)

Ground state phase diagram and critical temperature of two component
Bose gases with Rashba spin-orbit coupling

Zeng-Qiang Yu
In this work, we present ground state phase diagram of two component Bose gases with Rashba spin-orbit coupling. In addition to plane-wave condensate and spin density wave condensate which have been studied previously, a new phase that the fully polarized condensate occupies zero momentum is identified. This zero momentum phase competes with spin density wave phase when inter-species interaction is stronger than intra-species interaction, and the former one is always the ground state for weak enough spin-orbit coupling. When the energies of these two phases are close, there is a phase separation between them. At finite temperature, such a zero momentum condensation can be induced by a ferromagnetic phase transition in normal state. The spontaneous spin polarization generates an effective internal Zeeman field, and removes the degeneracy of quasi-particles energy minima. Consequently, the modified density-of-state accommodate a Bose condensation to appear below a critical temperature.
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