Competing magnetic and superconducting order and the role of vortices in iron-based superconductors

ORAL

Abstract

We discuss recent neutron and muSR measurements of the magnetic and superconducting (SC) properties of Co-doped Ba-122 as a function of temperature and external magnetic field [1]. Below the T$_{\mathrm{c}}$, the magnetic and SC order parameters coexist and compete. A magnetic field can significantly enhance the magnetic scattering in the SC state [1]. We perform a microscopic modeling of the data by use of a five-band Hamiltonian relevant to iron pnictides. In the SC state, vortices can slow down and freeze spin fluctuations locally. When such regions couple they result in a long-range ordered antiferromagnetic phase producing the enhanced magnetic elastic scattering in agreement with experiments [1]. Lastly, we also study the low energy bound states in the vortex core of LiFeAs, where the quasiparticle states in the vortex core can provide useful information about the gap structure [2]. \\[4pt] [1] J. Larsen, G. Stieber, S. L. Holm, K. Lefmann, C. Niedermayer, T. Wolf, preprint 2014\\[0pt] [2] B. Mencia Uranga, B. M. Andersen, preprint 2014

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Authors

  • B. Mencia Uranga

    • Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark

  • J. Larsen

    • Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark

  • G. Stieber

    • Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark

  • S.L. Holm

    • Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark

  • K. Lefmann

    • Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark

  • C. Niedermayer

    • Paul Scherrer Institut Villigen
    • Laboratory for Neutron Scattering and Imaging, Paul Scherrer Institute, CH-5232 Villigen, Switzerland

  • Thomas Wolf

    • Karlsruher Institut fur Technologie, Institut fur Festkorperphysik, 7602, Karlsruhe, Germany
    • Karlsruher Institut fuer Technologie, Institut fuer Festkoerperphysik, D-76021 Karlsruhe, Germany
    • Institut f\"{u}r Festk\"{o}rperphysik, Karlsruhe Institute of Technology, Germany

  • B.M. Andersen

    • Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen, Denmark