The Surface Structure of FeTe$_{1-x}$Se$_{x}$: A LEED/STM Study

ORAL

Abstract

We have utilized low energy electron diffraction (LEED $I-V)$ and scanning tunneling microscopy (STM) to investigate the structural properties of FeTe$_{1-x}$Se$_{x}$ ($x$ = 0 and 0.45) surface. The LEED pattern indicates there is no surface reconstruction on both parent and doped compounds. However, the detailed surface structure calculations from LEED $I-V$ show the cleaved surface of FeTe is Te termination with a 0.06 {\AA} compression on the top layer. The STM topography shows the extreme flatness of the FeTe surface with a corrugation of less than 8 pm. The high resolution STM topography indicates that nanoscale chemical phase separation between Te and Se atoms is unambiguously revealed on the surface of FeTe$_{0.55}$Se$_{0.45}$. Chemical phase separation on the nanoscale makes the LEED $I-V$ surface structural analysis of FeTe$_{1-x}$Se$_{x}$ (001) very challenging. We will discuss the solution of the LEED analysis and the STM observations as a function of $x.$

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Authors

  • Xiaobo He

    Louisiana State University, Baton Rouge, LA 70803, USA, Louisiana State University

  • Von Braun Nascimento

    Louisiana State University, Louisiana State University, Baton Rouge, LA 70803, USA

  • Guorong Li

    Louisiana State University, Louisiana State University, Baton Rouge, LA 70803, USA

  • Jiandi Zhang

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

  • Rongying Jin

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

  • Athena Safa-Sefat

    Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA, Oak Ridge National Laboratory, Oak Ridge, TN, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • Michael McGuire

    Oak Ridge National Laboratory, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • B.C. Sales

    Oak Ridge National Laboratory, Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 USA, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA

  • David Mandrus

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

  • E.W. Plummer

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