BaFe2As2 Surface Domains and Domain Walls: Mirroring the Bulk Spin Structure

ORAL

Abstract

We have used scanning tunneling microscopy/spectroscopy (STM/STS) to investigate the geometric and electronic structure at the (001) surface of the parent compound BaFe$_{2}$As$_{2}$. While high-resolution STM measurements reveals a (1x1) As-terminated unit cell on the (001) surface, there are significant differences of the surface unit cell compared to the bulk: only one of the two As atoms in the unit cell is imaged and domain walls between different (1x1) regions display a C2 symmetry at the surface. It should have been C2v if the STM image reflected the geometric structure of the surface or the orthorhombic bulk. The inequivalent As atoms and the bias dependence of the domain walls indicate that the origin of the STM image is primarily electronic not geometric. We argue that the surface electronic topography mirrors the bulk spin structure of BaFe2As2, via strong orbital-spin coupling.

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Authors

  • Guorong Li

    Louisiana State University, LA

  • Xiaobo He

    Louisiana State University, LA

  • Ang Li

    University of Houston, Houston, TX

  • Shuheng Pan

    University of Houston, TX

  • Jiandi Zhang

    Louisiana State University, LA

  • Rongying Jin

    Louisiana State University, LA, Department of Physics and Astronomy, Louisiana State University

  • Athena S. Sefat

    Oak Ridge National Laboratory, TN

  • Michael A. McGuire

    Oak Ridge National Laboratory, TN

  • David G. Mandrus

    Oak Ridge National Laboratory and The University of Tennessee, TN

  • Brain C. Sales

    Oak Ridge National Laboratory, TN

  • E.W. Plummer

    Louisiana State University, LA, Department of Physics and Astronomy, Louisiana State University