171 research outputs found

    Nonlinear sigma model approach for chiral fluctuations and symmetry breakdown in Nambu-Jona-Lasinio model

    Get PDF
    In this paper we discuss symmetry breakdown in NJL model at low N_c. In particular we propose a modified NJL model that displays a symmetry breakdown and also at finite temperatures under certain conditions the chiral fluctuations in this model give rise to a phase analogous to pseudogap phase of strong-coupling and low carrier density superconductors.Comment: accepted to Phys. Rev. D. Latest updates of this and related papers are available at http://www.teorfys.uu.se/PEOPLE/egor

    Rotational response of superconductors: magneto-rotational isomorphism and rotation-induced vortex lattice

    Full text link
    The analysis of nonclassical rotational response of superfluids and superconductors was performed by Onsager (in 1949) \cite{Onsager} and London (in 1950) \cite{London} and crucially advanced by Feynman (in 1955) \cite{Feynman}. It was established that, in thermodynamic limit, neutral superfluids rotate by forming---without any threshold---a vortex lattice. In contrast, the rotation of superconductors at angular frequency Ω{\bf \Omega}---supported by uniform magnetic field BLΩ{\bf B}_L\propto {\bf \Omega} due to surface currents---is of the rigid-body type (London Law). Here we show that, neglecting the centrifugal effects, the behavior of a rotating superconductor is identical to that of a superconductor placed in a uniform fictitious external magnetic filed H~=BL\tilde{\bf H}=- {\bf B}_L. In particular, the isomorphism immediately implies the existence of two critical rotational frequencies in type-2 superconductors.Comment: replaced with published versio

    Unusual mechanism of vortex viscosity generated by mixed normal modes in superconductors with broken time reversal symmetry

    Full text link
    We show that under certain conditions multiband superconductors with broken time-reversal symmetry have a new vortex viscosity-generating mechanism which is different from that in conventional superconductors. It appears due to the existence of mixed superfluid phase-density mode inside vortex core. This new contribution is dominant near the time reversal symmetry breaking phase transition. The results could be relevant for three band superconductor Ba1xKxFe2As2Ba_{1-x}K_{x}Fe_2As_2.Comment: 7 pages, 2 figure

    Domain walls and their experimental signatures in s+is superconductors

    Full text link
    Arguments were recently advanced that hole-doped Ba1x_{1-x}Kx_xFe2_2As2_2 exhibits s+iss+is state at certain doping. Spontaneous breaking of time reversal symmetry in s+iss+is state, dictates that it possess domain wall excitations. Here, we discuss what are the experimentally detectable signatures of domain walls in s+iss+is state. We find that in this state the domain walls can have dipole-like magnetic signature (in contrast to the uniform magnetic signature of domain walls p+ipp+ip superconductors). We propose experiments where quench-induced domain walls can be stabilized by geometric barriers and be observed via their magnetic signature or their influence on the magnetization process, thereby providing an experimental tool to confirm s+iss+is state.Comment: Replaced with a version in print in Physical Review Letters; Minor changes; 8 pages, 9 figure
    corecore