Temperature-concentration phase diagram and multigap superconductivity revealed by soft point-contact spectroscopy in (Ca $_{\mathrm{1-x}}$ La$_{\mathrm{x}})_{10}$(Pt$_3$As$_8)$(Fe$_2$As$_2)_5$

ORAL

Abstract

Sizable single crystals of the superconducting iron-pnictide system (Ca $_{\mathrm{1-x}}$ La$_{\mathrm{x}})_{10}$(Pt$_{3}$As$_{\mathrm{8}})$(Fe$_{2}$As$_{2})_{5}$ (x$=$0 to 0.182) have been grown and characterized by X-ray, microscopic, resistivity, Hall coefficient, susceptibility and specific heat measurements. Features in magnetic susceptibility, specific heat and two kinks in the derivative of the electrical resistivity around 100 K in the x$=$0 compound support the existence of decoupled structural and magnetic phase transitions. With La doping, the structural/magnetic phase transitions are suppressed and a dome of superconductivity with a maximal T$_{\mathrm{c}}$ up to 23 K is observed in the temperature-concentration phase diagram. Soft point-contact spectroscopy was performed on the optimally doped sample of x$=$0.145. By fitting the multigap Blonder-Tinkham-Klapwijk(BTK) model to the data, three gaps with $\Delta _{1}=$1 meV, $\Delta_{2}=$8 meV and $\Delta _{3}=$27 meV are revealed. Acknowledgement: Work at Los Alamos was performed under the auspices of the US DOE.

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Authors

  • Ni Ni

    Los Alamos National Lab

  • Eunsung Park

    Los Alamos National Lab \& Department of Physics, Sungkyunkwan University

  • Warren Straszheim

    Department of Physics and Astronomy, Iowa State University, Ames Laboratory, US DOE, Iowa State University

  • Xin Lu

    Los Alamos National Laboratory, Los Alamos National Lab

  • Darrick J. Williams

    Los Alamos National Lab

  • Makariy Tanatar

    Department of Physics and Astronomy, Iowa State University, Ames Laboratory USDOE and Iowa State University, Ames Laboratory

  • Ruslan Prozorov

    Ames Laboratory and Iowa State University, Department of Physics and Astronomy, Iowa State University, The Ames Laboratory, Ames, Iowa 50011, USA Department of Physics \& Astronomy, Iowa State University, Ames, Iowa 50011, USA, Ames Lab

  • Eric Bauer

    Los Alamos National Laboratory, Los Alamos National Lab

  • Filip Ronning

    Los Alamos National Laboratory, Los Alamos National Lab

  • Joe Thompson

    Los Alamos National Laboratory, Los Alamos National Lab, MPA-CMMS, LANL

  • Robert Cava

    Department of Chemistry, Princeton University, Dept. Chem. Princeton University, New Jersey 08544, Princeton University, Department of Chemistry, Princeton University, Princeton, NJ 08544, USA