University of Minnesota
School of Physics & Astronomy

Condensed Matter Seminar

Thursday, November 8th 2007
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Daniel Sheehy, Iowa State
Subject: The Low-Temperature Phases of Polarized Fermionic Superfluids

A number of recent experiments have achieved paired superfluidity of trapped fermionic atomic gases. Such pairing, occurring between two atomic hyperfine-state species (forming a pseudo-spin-1/2 system), is possible due to the strong attractive interactions provided by a magnetic field tuned Feshbach resonance (FR). At equal populations, the superfluidity of resonantly interacting Fermi gases undergoes the well-studied crossover between Bardeen-Cooper-Schrieffer (BCS) pairing and Bose-Einstein condensation (BEC) as a function of FR detuning (or
interaction strength). I will discuss recent work aimed at
understanding the case of unequal populations (i.e., imposed
spin polarization), an easily controllable experimental knob that is predicted to interrupt the continuous equal-population BCS-BEC
crossover, yielding a variety of distinct phenomena including regions of singlet paired superfluid, unpaired polarized normal Fermi liquid, polarized Fulde-Ferrell-Larkin-Ovchinnikov superfluid, polarized magnetic superfluid, and phase-separated mixtures of these uniform states.

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