Multi-band nature and anisotropy of heavily doped Ba$_{1-x}$K$_x$Fe$_2$As$_2$

ORAL

Abstract

We have carried out a detailed study on single crystals of Ba$_{\mathrm{1-x}}$K$_{\mathrm{x}}$Fe$_{2}$As$_{2}$ with doping level x very close to 1, Ba$_{0.05}$K$_{0.95}$Fe$_{2}$As$_{2}$ with T$_{\mathrm{c}} = $ 6.6 K, which exceeds the Lifshitz transition around x $=$ 0.9. The heat capacity C(T) shows a relatively large nodeless energy gap of 1.93 k$_{\mathrm{B}}$T$_{\mathrm{c}}$ based on a three-band BCS model analysis, which suggests that the SC state with the biggest gap value shows a fully opened s-wave superconducting characteristic and a possible nodal gap that shows a rather small gap value. A full H-T phase diagram has been determined by measuring C(T) and resistivity under fields in ab plane and c direction. Angle-resolved resistivity measurements at low temperatures were used to probe the angular dependence of upper critical field, showing an anisotropy well explained by using the Ginzburg-Landau theory.

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Authors

  • Shuai Zhang

    Kent State University

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville

  • Frazier Baker

    Youngstown State University, Kent State University, Liquid Crystal Institute, Kent State University, Department of Biological Sciences, Kent State University, Department of Physics, Department of Chemistry and Biochemistry, Kent State University, Stony Brook Univ, Ohio Univ, Institute for Advanced Simulation, Institut fur Kernphysik, and Julich Center, Bowling Green State University, Dept. of Physics, Hiram College, Ohio State Univ - Columbus, Kent State University, Psychology Dept, Cleveland State University, Physics Dept, Cleveland State University, Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242-0001, USA, Univ of Konstanz, Univ College London, NIST, Hiroshima Univ, KIT, Missouri University of Science and Technology, University of California, San Diego, Georgia Institute of Technology, KSU, SKKU, Lock Haven Univ, Massachusetts General Hospital, University of Science and Technology of China, Yale University, Shanghai Institute of Microsystem and Information Technology, CAS, Nanjing University, Liquid Crystal Institute and Chemical Physics Interdisciplinary Program, Kent State University, Kent, OH 44242, USA, Department of Physics, Kent State University, Kent OH 44242, Department of Electro-Optic Engineering Ilse Katz Institute for Nanoscale Science and Technology Ben Gurion University, Beer Sheva 84105, Israel, Ohio University Zanesville