Critical Temperature in the BCS-BEC Crossover with Spin-Orbit Coupling

Condensed Matter

Luca Dell’Anna¹  Stefano Grava² 

[1] Dipartimento di Fisica e Astronomia “G. Galilei”, University of Padova, Via F. Marzolo 8, 35151 Padova, Italy;ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Castelldefels, 08860 Barcelona, Spain;

关键词: BCS-BEC crossover;    superfluidity;    critical temperature;   

DOI  :  10.3390/condmat6020016

来源: DOAJ

【 摘 要 】

We review the study of the superfluid phase transition in a system of fermions whose interaction can be tuned continuously along the crossover from Bardeen–Cooper–Schrieffer (BCS) superconducting phase to a Bose–Einstein condensate (BEC), also in the presence of a spin–orbit coupling. Below a critical temperature the system is characterized by an order parameter. Generally a mean field approximation cannot reproduce the correct behavior of the critical temperature $T_c$ over the whole crossover. We analyze the crucial role of quantum fluctuations beyond the mean-field approach useful to find $T_c$ along the crossover in the presence of a spin–orbit coupling, within a path integral approach. A formal and detailed derivation for the set of equations useful to derive $T_c$ is performed in the presence of Rashba, Dresselhaus and Zeeman couplings. In particular in the case of only Rashba coupling, for which the spin–orbit effects are more relevant, the two-body bound state exists for any value of the interaction, namely in the full crossover. As a result the effective masses of the emerging bosonic excitations are finite also in the BCS regime.

【 授权许可】

Unknown