Competition between external and synthetic magnetic fields on a spin-1 ultracold Bose gas

Department of Physics, Indian Institute of Technology Guwahati - Guwahati, Assam 781039, India

^(a) Saurabh@iitg.ernet.in

Received: 15 September 2016
Accepted: 5 December 2016

Abstract

We study a spin-1 ultracold Bose gas in the presence of both external and synthetic magnetic fields via mean-field approach corresponding to both signs of the spin-dependent interaction potential. The synthetic field is included through the hopping frequencies via Peierls coupling and the external field through the Zeeman interaction term to explore the influence of one over the other. The antiferromagnetic case shows that at low values of external field strengths, the spin singlet state is stable and the system is more likely in Mott insulating (MI) phase as the synthetic field is enhanced. But at large external fields, due to a competition between the hopping and the Zeeman interaction terms, the former tends to stabilize the MI phase compared to the superfluid (SF) phase, while the latter tries to destabilize the MI phase by suppressing the formation of singlet pairs. In the ferromagnetic case, insensitivity of the phase properties to the external magnetic field leads to stabilization of the MI phase with increasing synthetic magnetic field. Further the magnetization shows that there are distinct signatures of transverse polar and longitudinal ferro SF phases for both antiferromagnetic and ferromagnetic interactions, respectively.