Charge carrier localization induced by excess Fe in the Fe$_{1+y}$(Te$_{1-x}$Se$_{x})$ superconductor system

ORAL

Abstract

Iron chalcogenide Fe$_{1+y}$(Te$_{1-x}$Se$_{x})$ is the simplified version of Fe-based superconductors. Its non-superconducting parent compound Fe$_{1+y}$Te exhibits an AFM structure distinct from those seen in undoped FeAs compounds. Understanding of the superconducting properties of this system has been considered critical. We have investigated the effect of Fe nonstoichiometry on properties of the Fe$_{1+y}$(Te$_{1-x}$Se$_{x})$ superconductor system by means of resistivity, Hall coefficient, magnetic susceptibility, and specific heat measurements. We find that the excess Fe at interstitial sites of the (Te, Se) layers not only suppresses superconductivity, but also results in a weakly localized electronic state. Together with neutron scattering studies and recent DFT calculations, our results suggest that such weak charge carrier localization originates from the magnetic coupling between the excess Fe and the adjacent Fe square planar sheets.

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Authors

  • Jin Hu

    Tulane University

  • Tijiang Liu

    Tulane University

  • Xianglin Ke

    The Pennsylvania State University

  • Qian Bin

    Tulane University

  • David Fobes

    Tulane University, Department of Physics, Tulane University, New Orleans, LA 70118

  • Erin Vehstedt

    Tulane University

  • Huy Pham

    University of New Orleans, Tulane University

  • Jinhu Yang

    Zhejiang University

  • Minghu Fang

    Zhejiang University

  • Leonard Spinu

    University of New Orleans

  • Peter Schiffer

    The Pennsylvania State University, Dept. of Physics, Penn State University, University Park PA 16802, Pennsylvania State University

  • Ying Liu

    Pennsylvania State University, The Pennsylvania State University

  • Zhiqiang Mao

    Tulane University, Tulane Unversity, Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118