Stoner ferromagnetism of a strongly interacting Fermi gas in the quasirepulsive regime

Abstract

Recent advances in rapidly quenched ultracold atomic Fermi gases near a Feshbach resonance have brought about a number of interesting problems, in the context of observing the long-sought Stoner ferromagnetic phase transition. The possibility of experimentally obtaining a "quasirepulsive" regime in the upper branch of the energy spectrum due to the rapid quench is currently being debated, and the Stoner transition has mainly been investigated theoretically by using perturbation theory or at high polarization, due to the limited theoretical approaches in the strongly repulsive regime. In this work, we present a nonperturbative theoretical approach to the quasirepulsive upper branch of a Fermi gas near a broad Feshbach resonance, and we determine the finite-temperature phase diagram for the Stoner instability. Our results agree well with the known quantum Monte-Carlo simulations at zero temperature, and we recover the known virial expansion prediction at high temperature for arbitrary interaction strengths. At resonance, we find that the Stoner transition temperature becomes of the order of the Fermi temperature, around which the molecule formation rate becomes vanishingly small. This suggests a feasible way to observe Stoner ferromagnetism in the nondegenerate temperature regime.

Published version in Physical Review A

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Cited by in corpus (17)

• Exploring the ferromagnetic behaviour of a repulsive Fermi gas via spin dynamics
• Time-resolved observation of competing attractive and repulsive short-range correlations in strongly interacting Fermi gases
• Repulsive Fermi Polarons and Their Induced Interactions in Binary Mixtures of Ultracold Atoms
• Unified description of dynamics of a repulsive two-component Fermi gas
• On the Stability of the Repulsive Fermi Gas with Contact Interactions
• Breakdown of the Fermi polaron description near Fermi degeneracy at unitarity
• Repulsive polarons in alkaline-earth(-like) atoms across an orbital Feshbach resonance
• Repulsive Fermi polarons with negative effective mass
• Two-dimensional Mixture of Dipolar Fermions: Equation of State and Magnetic Phases
• Many-body molecule formation at a domain wall in a one-dimensional strongly interacting ultracold Fermi gas
• Nonzero temperature dynamics of a repulsive two-component Fermi gas
• Non-Hermitian Ferromagnetism in an Ultracold Fermi Gas
• Large-$N$ properties of a non-ideal Bose gas
• Third order corrections to the ground state energy of the gas of spin $s$ fermions with arbitrary densities of different spin projections
• Itinerant ferromagnetism of a dipolar Fermi gas with Raman-induced spin-orbit coupling
• Phase Transitions of Repulsive Two-Component Fermi Gases in Two Dimensions
• Metastability of Bose and Fermi gases on the upper branch