Intrinsic interfacial monolayers and their effect on the high-temperature superconductor FeSe / SrTiO<sub>3</sub>

ORAL

Abstract

It was recently demonstrated that monolayer FeSe on SrTiO3 is a superconductor with Tc between 60 and 100 K, compared to 8 K in bulk FeSe. In contrast, Tc has been measured to be only 3.7 K in bi-layer FeSe deposited on graphene (extrapolated to about 2 K in a monolayer), pointing to the major role of the interface in enhancing superconductivity. Here we determine the atomic structure of an interfacial layer and identify its role in driving the increase in Tc using a combination of quantum mechanical calculations and scanning transmission electron microscopy. Within our DFT calculations, this interfacial layer hosts magnetic and orbital order not found in the typical TiO2 surface termination nor in other surface reconstructions. Interactions between this interfacial monolayer and FeSe generate symmetry-breaking distortions in the film that are favorable for increasing Tc and are not present in other possible FeSe / STO interface structures. We propose that this may provide a path forward toward the design and enhancement of other two-dimensional superconductors.

*1. U.S. DOE grant DE-FG02-09ER46554, McMinn endowment
2. U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division
3. U.S. National Science Foundation, DMR-1335215

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Presenters

  • Hunter Sims

    • Physics and Astronomy, Vanderbilt University

Authors

  • Hunter Sims

    • Physics and Astronomy, Vanderbilt University

  • Donovan Leonard

    • Materials Science and Technology Division, Oak Ridge National Lab

  • Axiel Birenbaum

    • Materials Science and Technology Division, Oak Ridge National Lab

  • Zhuozhi Ge

    • Physics and Astronomy, West Virginia University
    • Department of Physics and Astronomy, West Virginia University

  • Lian Li

    • Physics and Astronomy, West Virginia University
    • West Virginia Univ
    • Department of Physics and Astronomy, West Virginia University

  • Valentino Cooper

    • Oak Ridge National Lab
    • Oak Ridge National Laboratory
    • Materials Science & Technology Division, Oak Ridge National Lab
    • Materials Science and Technology Division, Oak Ridge National Lab
    • ORNL
    • Materials Science and Technology Division, Oak Ridge National Laboratory

  • Matthew Chisholm

    • Oak Ridge National Laboratory
    • Materials Science and Technology Division, Oak Ridge National Lab
    • Materials Science and Technology Division, Oak Ridge National Laborotory

  • Sokrates Pantelides

    • Department of Physics and Astronomy, Vanderbilt University
    • Vanderbilt University
    • Physics and Astronomy, Vanderbilt University
    • Department of Physics and Astronomy and Department of Electrical Engineering and Computer Science, Vanderbilt University
    • Dept. of Physics and Astronomy , Vanderbilt University
    • Vanderbilt Univ
    • Physics, Vanderbilt Univ