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 $x.$

*Supported by NSF DMR-1002622

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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