Itinerant ferromagnetism of two-dimensional repulsive fermions with Rabi coupling

Abstract

We study a two-dimensional fermionic cloud of repulsive alkali-metal atoms characterized by two hyperfine states which are Rabi coupled. Within a variational Hartree-Fock scheme, we calculate analytically the ground-state energy of the system. Then we determine the conditions under which there is a quantum phase transition with spontaneous symmetry breaking from a spin-balanced configuration to a spin-polarized one, an effect known as itinerant ferromagnetism. Interestingly, we find that the transition appears when the interaction energy per particle exceedes both the kinetic energy per particle and the Rabi coupling energy. The itinerant ferromagnetism of the polarized phase is analyzed, obtaining the population imbalance as a function of interaction strength, Rabi coupling, and number density. Finally, the inclusion of a external harmonic confinement is investigated by adopting the local density approximation. We predict that a single atomic cloud can display population imbalance near the center of the trap and a fully balanced configuration at the periphery.

12 pages, 3 figures, to be published in New Journal of Physics

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Cited by in corpus (9)

• Equation of state and self-bound droplet in Rabi-coupled Bose mixtures
• Collective modes across the soliton-droplet crossover in binary Bose mixtures
• Probing Ferromagnetic Order in Few-Fermion Correlated Spin-Flip Dynamics
• Supersolid-Superfluid phase separation in the extended Bose-Hubbard model
• Quantum Monte Carlo simulations of two-dimensional repulsive Fermi gases with population imbalance
• Interplay of phase separation and itinerant magnetism for correlated few fermions in a double-well
• Polarization in a three-dimensional Fermi gas with Rabi coupling
• Rabi coupled fermions in the BCS-BEC crossover
• Phase Transitions of Repulsive Two-Component Fermi Gases in Two Dimensions