Eur. Phys. J. D (2016) 70: 230
https://doi.org/10.1140/epjd/e2016-70374-3

Regular Article

BCS-BEC crossover in a relativistic boson-fermion model with a synthetic gauge field

¹ School of Science, Tianjin University of Science and Technology, Tianjin 300457, P.R. China
² Department of Basic Courses, Tianjin University of Finance and Economics Pearl River College, Tianjin 301811, P.R. China
³ School of Science, Tianjin University of Technology and Education, Tianjin 300222, P.R. China
⁴ Laboratory for Quantum Engineering and Micro-Nano Energy Technology, School of Physics and Optoelectronics, Xiangtan University, Hunan 411105, P.R. China
⁵ School of Mathematics and Computer Science, Guizhou Normal University, Guizhou 550001, P.R. China

^a e-mail: gxyauthor@tust.edu.cn

Received: 5 June 2016
Received in final form: 10 August 2016
Published online: 1 November 2016

Abstract

We investigate the influence of a synthetic gauge field on the BCS-BEC crossover in a relativistic superfluid. The configuration of the gauge field generates an effective Rashba spin-orbit coupling. Extending the relativistic boson-fermion model to include such an effect, we construct a mean-field theory which provides a qualitative understanding at both zero and critical temperatures. The synthetic gauge field induces a novel long-range fermionic pairing state. The BCS-BEC crossover can be realized by tuning the difference between boson mass and boson chemical potential or by changing the gauge coupling strength. Particularly, the increasing gauge coupling strength drives a crossover from the condensate boson molecules to the superfluid fermion pairs. Moreover, the presence of the gauge field suppresses the critical temperature, whose magnitude is vanishingly small in the BCS and finite in the BEC regime.