We calculate the critical temperature of a superfluid phase transition in a polarized Fermi gas of dipolar particles. In this case the order parameter is anisotropic and has a nontrivial energy dependence. Cooper pairs do not have a definite value of the angular momentum and are coherent superpositions of all odd angular momenta. Our results describe prospects for achieving the superfluid transition in single-component gases of fermionic polar molecules.

We study the superconducting order parameter fluctuations near the phase transition into the Larkin-Ovchinnikov-Fulde-Ferrell state in the clean limit at zero temperature. In contrast to the usual normal metal-to-uniform superconductor phase transition, the fluctuation corrections are dominated by the modes with the wave vectors away from the origin. We find that the superconducting fluctuations lead to a divergent spin susceptibility and a breakdown of the Fermi-liquid behavior at the quantum critical point.

We consider the temperature dependence of the sound attenuation and sound velocity in layered impure metals due to s-wave superconducting fluctuations of the order parameter above the critical temperature. We obtain the dependence on material properties of these fluctuation corrections in the hydrodynamic limit, where the electron mean free path ℓ is much smaller than the wavelength of sound and where the electron collision rate τ −1 is much larger than the sound frequency. For longitudinal sound propagating perpendicular to the layers, the open Fermi surface condition leads to a suppression of the divergent contributions to leading order, in contrast with the case of paraconductivity. The leading temperature dependent corrections, given by the Aslamazov-Larkin, Maki-Thompson and density of states terms, remain finite as T → Tc. Nevertheless, the sensitivity of new ultrasonic experiments on layered organic conductors should make these fluctuations effects measurable.PACS numbers: 74.25. Ld, 74.25.Fy, 74.40.+k The problem of fluctuations of the superconducting order parameter above the critical temperature began to attract the attention of researchers more than three decades ago. [1, 2, 3] Considerable work has been done from both the theoretical and experimental points of view. Conductivity, thermoconductivity, magnetoconductivity as well as tunneling properties and nuclear magnetic resonance characteristics are amongst the various transport phenomena where fluctuation contributions were predicted and experimentally observed. Ref. [4] contains an extensive review of the field and references.In the present paper, we concentrate on the superconducting fluctuation corrections to the sound velocity and sound attenuation in layered superconductors above T c . As usual, superconducting fluctuations manifest themselves in three different ways.[4] a) The effective number of normal carriers is reduced because some of the electrons exist as transient Cooper pairs. This is the so-called density of states contribution. b) The single-particle excitations are Andreev reflected off the superconducting fluctuations, as described by the so-called Maki-Thompson term. c) Some of the electrons behave like Cooper pairs for a time given by the Ginzburg-Landau time. This is the famous AslamazovLarkin contribution. Layered organic superconductors, in particular, are an ideal class of materials to study fluctuation phenomena. This is because the relatively low charge-carrier concentration and the strong electronic anisotropy enhance the effect of superconducting fluctuations and increase the size of the fluctuation regime. The manifestation of superconducting fluctuations in organic materials was found in a number of experimental works on dc-magnetoconductivity, thermoconductivity, ac-susceptibility, specific heat and torque magnetometry. [5] Preliminary ultrasonic experiments in the κ-phase layered organic materials [6] (BEDT-Cl and (BEDT-TTF) 2 Cu(NCS) 2 suggest that the sound attenuation coefficient is decreased by superconducting...