Séminaire du LPTMS: A. Bouzdin


11:00 - 12:00

LPTMS, salle 201, 2ème étage, Bât 100, Campus d'Orsay
15 Rue Georges Clemenceau, Orsay, 91405
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Non-uniform (FFLO) states and quantum oscillations in superconductors and superfluid ultracold Fermi gases

A. Buzdin, Université de Bordeaux

A long time ago, it was predicted by Larkin and Ovchinnikov and Fulde and Ferrell that the non-uniform superconducting state (FFLO state) must appear in the magnetic field acting on the electron spins. We start with the discussion of the distinctive features of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) non-uniform superconducting state and review recent experiments on the heavy fermion superconductor CeCoIn5 and layered organic superconductors providing strong evidences in favor of FFLO phase observation. It is demonstrated that in 2D ( or quasi 2D) superconductors the FFLO state leads to an appearance of a very special oscillatory – like dependence of the upper critical field versus the field orientation.
Interestingly, in the superconductor-ferromagnet heterostructures the FFLO-like state may result in the formation of the Josephson junction with a spontaneous phase difference.

The FFLO-type instability may be also expected in ultracold Fermi gases in magneto-optical traps. In these systems it is caused not by the Zeeman interaction but by the tuning of the population imbalance between two lowest hyperfine states of the atoms. We briefly discuss the properties of such FFLO state and analyze the role the trapping potential confining the condensate.

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