Local topography and spectroscopy of the doped chalcogenide FeTe$_{x}$Se$_{1-x}$

ORAL

Abstract

The atomically resolved structural and electronic properties of FeTe and FeTe$_{0.55}$Se$_{0.45}$ have been investigated using scanning tunneling microscopy/spectroscopy. The STM topography of the doped sample clearly distinguishes two types of atoms. Statistically the topography shows the correct concentration of the two species and reveals that they are not randomly distributed but prefer to congregate with tens of identical atoms in nanometer scale. Consequently, in contrast to extremely flat surface of parent compound FeTe, FeTe$_{0.55}$Se$_{0.45}$ shows structural phase separation globally breaking the pure \textit{p4/nmm} symmetry. Surprisingly the local density of states on tellurium and selenium atoms in FeTe$_{0.55}$Se$_{0.45}$ are identical, but not the same as that in pure FeTe. This indicates an itinerant (rather than localized) electronic character in this doped system. This behavior is opposite to phase separation in many other doped materials.

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Authors

  • Xiaobo He

    Louisiana State University, Baton Rouge, LA 70803, USA, Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802, USA

  • Guorong Li

    Louisiana State University, Baton Rouge, LA 70803, USA, Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802, USA, Louisiana State University

  • Jiandi Zhang

    Louisiana State University, Baton Rouge, LA 70803, USA, Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802, USA, Louisiana State University

  • Rongying Jin

    Louisiana State University, Louisiana State University, Baton Rouge, LA 70803, USA, Department of Physics and Astronomy, Louisiana State University, Louisiana State University, Baton Rouge LA, Louisiana State University, USA, Dept. of Physics, Louisiana State University, Baton Rouge, LA 70802, USA

  • A.S. Sefat

    ORNL, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory, MST Division, Oak Ridge National Laboratory, ORNL, Oak Ridge, TN, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA, Materials Science \& Technology Division, ORNL, Oak Ridge, TN 37831, USA

  • M.A. McGuire

    ORNL, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory, Materials Science \& Technology Division, ORNL, Oak Ridge, TN 37831, USA

  • B.C. Sales

    ORNL, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Oak Ridge National Laboratory, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN 37831, USA, Materials Science \& Technology Division, ORNL, Oak Ridge, TN 37831, USA

  • David Mandrus

    University of Tennessee, Knoxville, TN, 37996, Oak Ridge National Laboratory

  • Ward Plummer

    Louisiana State University, Baton Rouge, LA 70803, USA, Louisiana State University, Department of Physics and Astronomy, Louisiana State University, Louisiana State University, Baton Rouge LA, Depart. of Physics, Louisiana State University, Baton Rouge, LA 70802, USA