2011/02/28 by P. Massignan, G. M. Bruun · 5 citations
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Coupling (piping) #Effective mass (spring–mass system) #Ferromagnetism #Impurity #Metastability #Physics of Superconductivity and Magnetism #Polaron #Quasiparticle #Scattering #Topological Materials and Phenomena #cond-mat.quant-gas #quant-ph
paper · pdf · doi:10.1140/epjd/e2011-20084-5
published as Eur. Phys. J. D 65, 83 (2011). Topical issue on "Cold Quantum Matter" · Substantial improvements to the section describing quasiparticle decays (included a discussion of two-body and three-body processes), and to the criteria for the stability of the itinerant ferromagnetic phase
arxiv created 2011/05/18 · openalex publication_date 2011/07/27 · arxiv updated 2011/11/28 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze the properties of a single impurity immersed in a Fermi sea. At positive energy and scattering lengths, we show that the system possesses a well-defined but metastable excitation, the repulsive polaron, and we calculate its energy, quasiparticle residue and effective mass. From a thermodynamic argument we obtain the number of particles in the dressing cloud, illustrating the repulsive character of the polaron. Identifying the important 2- and 3-body decay channels, we furthermore calculate the lifetime of the repulsive polaron. The stability conditions for the formation of fully spin polarized (ferromagnetic) domains are then examined for a binary mixture of atoms with a general mass ratio. Our results indicate that mass imbalance lowers the critical interaction strength for phase-separation, but that very short quasiparticle decay times will complicate the experimental observation of itinerant ferromagnetism. Finally, we present the spectral function of the impurity for various coupling strengths and momenta.