2 research outputs found
Polarons in the radio-frequency spectrum of a quasi-two-dimensional Fermi gas
We measure radio-frequency spectra for a two-component mixture of a Li
atomic Fermi gas in the quasi-two-dimensional regime. Near the Feshbach
resonance, where the transverse Fermi energy is large compared to the
confinement-induced dimer binding energies for the initial and final states, we
find that the observed resonances do not correspond to transitions between
confinement-induced dimers. The spectrum appears to be well-described by
transitions between noninteracting polaron states in two dimensions.Comment: 5 pages, 4 figures and supplementary material 4 pages, 3 figure
Repulsive polarons in two-dimensional Fermi gases
We consider a single spin-down impurity atom interacting via an attractive,
short-range potential with a spin-up Fermi sea in two dimensions (2D).
Similarly to 3D, we show how the impurity can form a metastable state (the
"repulsive polaron") with energy greater than that of the non-interacting
impurity. Moreover, we find that the repulsive polaron can acquire a finite
momentum for sufficiently weak attractive interactions. Even though the energy
of the repulsive polaron can become sizeable, we argue that saturated
ferromagnetism is unfavorable in 2D because of the polaron's finite lifetime
and small quasiparticle weight.Comment: 6 pages, 3 figure