Defects in Thin-Film FeSe/SrTiO$_3$: STM and DFT Investigations

ORAL

Abstract

A single-layer of FeSe deposited on SrTiO$_3$ exhibits an order-of-magnitude enhancement of its superconducting transition temperature compared to bulk FeSe. This dramatic effect is curiously absent in a second layer of FeSe deposited on the heterostructure, leading to many questions concerning the role of the interface structure, electron doping and phonon coupling. Here, we approach these questions by using STM to characterize and compare native defects that appear in multi-layer and single-layer FeSe/SrTiO$_3$ grown by MBE under excess Se flux. We use DFT to explore candidate defect configurations, formation energies and diffusion barriers, in order to gain atomic-scale insights into the growth and structure of these film heterostructures.

*Work supported by NSF DMR-1231319 (STC CIQM) and Moore Foundation EPiQS GBMF4536. Computations run on Harvard RC Odyssey.

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Authors

  • Dennis Huang

    • Harvard University

  • Tatiana A. Webb

    • University of British Columbia, Harvard University

  • Can-Li Song

    • Tsinghua University

  • Cui-Zu Chang

    • MIT
    • Massachusetts Inst of Tech-MIT
    • Massachusetts Institute of Technology

  • Jagadeesh S. Moodera

    • MIT
    • Department of Physics, Massachusetts Institute of Technology, Cambridge, MA-02139, USA
    • Francis Bitter Magnet Lab and Physics Department, Massachusetts Institute of Technology
    • Massachusetts Institute of Technology

  • Efthimios Kaxiras

    • Harvard University
    • John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

  • Jennifer E. Hoffman

    • University of British Columbia
    • Harvard University; The University of British Columbia
    • Harvard Univeristy
    • University of British Columbia, Harvard University