Exploring the ferromagnetic behaviour of a repulsive Fermi gas via spin dynamics

Abstract

Ferromagnetism is a manifestation of strong repulsive interactions between itinerant fermions in condensed matter. Whether short-ranged repulsion alone is sufficient to stabilize ferromagnetic correlations in the absence of other effects, like peculiar band dispersions or orbital couplings, is however unclear. Here, we investigate ferromagnetism in the minimal framework of an ultracold Fermi gas with short-range repulsive interactions tuned via a Feshbach resonance. While fermion pairing characterises the ground state, our experiments provide signatures suggestive of a metastable Stoner-like ferromagnetic phase supported by strong repulsion in excited scattering states. We probe the collective spin response of a two-spin mixture engineered in a magnetic domain-wall-like configuration, and reveal a substantial increase of spin susceptibility while approaching a critical repulsion strength. Beyond this value, we observe the emergence of a time-window of domain immiscibility, indicating the metastability of the initial ferromagnetic state. Our findings establish an important connection between dynamical and equilibrium properties of strongly-correlated Fermi gases, pointing to the existence of a ferromagnetic instability.

8 + 17 pages, 4 + 8 figures, 44 + 19 references

References in corpus (37)

• Feshbach Resonances in Ultracold Gases
• Metastability and Coherence of Repulsive Polarons in a Strongly Interacting Fermi Mixture
• Polarons, Dressed Molecules, and Itinerant Ferromagnetism in ultracold Fermi gases
• Metallic Quantum Ferromagnets
• Itinerant Ferromagnetism in a Fermi Gas of Ultracold Atoms
• Universal Spin Transport in a Strongly Interacting Fermi Gas
• Repulsive Fermi polarons in a resonant mixture of ultracold ${}^6$Li atoms
• Precise characterization of ^6Li Feshbach resonances using trap-sideband resolved RF spectroscopy of weakly bound molecules
• Inhomogeneous phase formation on the border of itinerant ferromagnetism
• Josephson effect in fermionic superfluids across the BEC-BCS crossover
• Excitation spectra and rf-response near the polaron-to-molecule transition from the functional renormalization group
• Itinerant ferromagnetism of a repulsive atomic Fermi gas: a quantum Monte Carlo study
• Itinerant Ferromagnetism in an Ultracold Atom Fermi Gas
• Competition between pairing and ferromagnetic instabilities in ultracold Fermi gases near Feshbach resonances
• Correlations and Pair Formation in a Repulsively Interacting Fermi Gas
• Stability of a Fully Magnetized Ferromagnetic state in Repulsively Interacting Ultracold Fermi Gases
• Ferromagnetism of quark liquid
• Transverse Demagnetization Dynamics of a Unitary Fermi Gas
• Fermi-Liquid Behavior of the Normal Phase of a Strongly Interacting Gas of Cold Atoms
• Speckle Imaging of Spin Fluctuations in a Strongly Interacting Fermi Gas
• Strongly interacting two-dimensional Fermi gases
• Efficient all-optical production of large ${}^6$Li quantum gases using D${}_1$ gray-molasses cooling
• Quantum mechanical limitations to spin diffusion in the unitary Fermi gas
• Repulsive Fermi gas in a harmonic trap: Ferromagnetism and spin textures
• Anomalous minimum in the shear viscosity of a Fermi gas
• Observation of the Leggett-Rice effect in a unitary Fermi gas
• Spin fluctuations, susceptibility and the dipole oscillation of a nearly ferromagnetic Fermi gas
• Spin-Dipole Oscillation and Polarizability of a Binary Bose-Einstein Condensate near the Miscible-Immiscible Phase Transition
• Compressibility of an Ultracold Fermi Gas with Repulsive Interactions
• Spin drag in an ultracold Fermi gas on the verge of a ferromagnetic instability
• Ferromagnetism of a Repulsive Atomic Fermi Gas in an Optical Lattice: a Quantum Monte Carlo Study
• The Nature and Properties of a Repulsive Fermi Gas in the "Upper Branch"
• Collision of two spin polarized fermionic clouds
• Stoner ferromagnetism of a strongly interacting Fermi gas in the quasirepulsive regime
• Colliding clouds of strongly interacting spin-polarized fermions
• Strong-coupling corrections to spin susceptibility in the BCS-BEC crossover regime of a superfluid Fermi gas
• Ferromagnetism in a Repulsive Atomic Fermi Gas with Correlated Disorder

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