Repulsive atomic Fermi gas with Rashba spin-orbit coupling: A quantum Monte Carlo study

Thanks to the recent experimental realization and control of artificial gauge fields, spin-orbit (SO) couplings are witnessing an ever increasing interest in the field of cold atoms. However, predicting their effect on spin polarization and energetic properties of interacting systems is a major challenge, due to the complex interplay between spin and position dynamics. In this work we exploit the diffusion Monte Carlo algorithm to compute energetic and polarization properties of a three-dimensional repulsive Fermi gas in the presence of Rashba spin-orbit coupling. We find that SO effects tend to contrast the spin alignment induced by the exchange interaction, slightly shifting the onset of the Stoner instability towards larger values of the scattering length. In addition, polarization and energy properties of the system can be tuned trough a combined control of the repulsive interaction and Rashba coupling.

Figure 1

Optimal $h$ as a function of the scattering length at $\lambda =0.3$.

Figure 2

Polarization of Fermi gas along the $z$ direction as a function of the two-body interaction scattering length $a$. Results are given in the absence of SO interaction ($\lambda =0$) and for two different Rashba interaction strengths ($\lambda =0.15,0.30$).

Figure 3

DMC energies as a function of $h$ at different values of the two-body interaction strength. The Rashba interaction coupling is fixed here to $\lambda =0.3$.

Figure 4

DMC energies (in units of $E_P$) as a function of the scattering length at different Rashba coupling strengths ($\lambda =0$, 0.15, 0.30).