Anisotropic Superconducting Properties and Pressure Effects in 1144-Structure-Type Pnictides

POSTER

Abstract

New Fe-based CaK-1144 superconductors (Fe-SC’s) with Tc ∼ 35 K were recently discovered. We grew phase-pure 1144 superconducting single crystals out of a quaternary molten solution of FeAs, self-flux. The crystal structure is determined by x-ray diffraction. The effects of pressure on Tc and the collapsed tetragonal phase transition are studied. In the superconducting state, temparature dependent magnetization and resistivity were measured under magnetic fields at different angles with respect to the basal plane. Lower critical field (Hc1), superfluid density (ρs), critical current densities, and the London penetration depth are extracted from magnetization data. Upper critical field (Hc2) and Irreversible field (Hirr) are determined by resistive transitions along c and ab directions. Various pairing gap functions were fit to the normalized ps(T) and specific heat data, and are compared with the nodeless two gap s± wave pairing symmetry reported by µSR and ARPES measurements. Normal-state magnetic susceptibility with characteristic T-dependence are used to discuss the possibility of antiferromagnetic spin fluctuations as the pairing mechanism in 1144 Fe-SC's will be presented.

Presenters

  • Kalyan Sasmal

    Department of Physics, University of California, San Diego, Physics, University of California, San Diego, Physics, Univ of California - San Diego

Authors

  • Kalyan Sasmal

    Department of Physics, University of California, San Diego, Physics, University of California, San Diego, Physics, Univ of California - San Diego

  • Christian Wolowiec

    Department of Physics, University of California, San Diego, Physics, University of California, San Diego, Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, Physics, Univ of California - San Diego

  • Zackary Rehfuss

    Department of Physics, University of California, San Diego

  • Yuankan Fang

    Department of Physics, University of California, San Diego

  • Naveen Pouse

    Department of Physics, University of California, San Diego

  • Alexander Breindel

    Department of Physics, University of California, San Diego

  • Trevor Keiber

    Department of Physics, University of California, San Diego

  • Sheng Ran

    Department of Physics, University of California, San Diego, Univ of California - San Diego, Physics, University of California, San Diego, Department of Physics, Univeristy of Maryland, Department of Physics, University of Maryland

  • M Brian Maple

    Department of Physics, University of California, San Diego, University of California, San Diego, Physics, University of California, San Diego, Univ of California - San Diego, Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, Department of Physics, Center for Advanced Nanoscience,Materials Science and Engineering Program , Univ of California - San Diego, Department of Physics, University of California San Diego, Physics, Univ of California - San Diego, University of California-San Diego, UC San Diego, Physics, UC San Diego