Low-Temperature Gated Raman Spectroscopy and Quantitative EELS of FeSe/STO

ORAL

Abstract

We characterize the phonon dynamics and interfacial charge transfer in FeTe-capped monolayer (ML) and few-layer FeSe films on SrTiO3 using low-temperature gated Raman spectroscopy and electron energy loss spectroscopy (EELS). In FeTe/ML FeSe/STO, we observe emergence of a silent STO mode at 264 cm-1 and slight hardening of STO phonons with an applied back-gate potential, consistent with the bare STO Raman response under electric field. Interestingly, we observe attenuation of the FeSe B3g peak accompanied by mild softening of both FeSe and FeTe modes, in sharp contrast to the STO dynamics. Notably, this behavior is absent in our measurement of the few-layer sample, suggesting an interplay between the STO and FeTe layer when the FeSe film is sufficiently thin. This is further corroborated by slight hardening of FeTe phonons as the FeSe film thickness is reduced, which we attribute to a non-local effect by the STO. Finally, the intrinsic charge transfer at the FeSe/STO interface is quantified through comparison of experimental and calculated EELS spectra and contrasted between the ML and few-layer samples.

*N.A. acknowledges National Science Foundation GRFP support under Grant No. 1122374 and experimental support from user facilities at Oak Ridge and Brookhaven National Laboratories.

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Presenters

  • Nina Andrejevic

    • Massachusetts Institute of Technology
    • Department of Materials Science and Engineering, Massachusetts Institute of Technology
    • Materials Science and Engineering, Massachusetts Institute of Technology

Authors

  • Nina Andrejevic

    • Massachusetts Institute of Technology
    • Department of Materials Science and Engineering, Massachusetts Institute of Technology
    • Materials Science and Engineering, Massachusetts Institute of Technology

  • Shengxi Huang

    • Electrical Engineering, Pennsylvania State University
    • Department of Electrical Engineering, Pennsylvania State University
    • School of Electrical Engineering and Computer Science, Pennsylvania State University
    • Pennsylvania State University

  • Qingping Meng

    • Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory

  • Alexander Puretzky

    • Oak Ridge National Laboratory
    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

  • David Geohegan

    • Center for Nanophase Materials Sciences, Oak Ridge National Laboratory

  • Cui-Zu Chang

    • Pennsylvania State University
    • Physics, Penn State University
    • Department of Physics, Pennsylvania State University
    • Physics, The Pennsylvania State University
    • Department of Physics, The Pennsylvania State University

  • Weiwei Zhao

    • School of Materials Science and Engineering, Harbin Institute of Technology
    • Department of Physics, Pennsylvania State University

  • Yimei Zhu

    • Department of Energy Science and Technology, Upton, New York 11973, USA, Brookehaven National Laboratory
    • Condensed Matter Physics & Materials Science Department, Brookhaven National Laboratory
    • Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory
    • Brookhaven National Laboratory
    • CMPMSD, Brookhaven National Laboratory
    • 2Condensed Matter Physics and Materials Science Departement, Brookhaven National Laboratory

  • Lijun Wu

    • Department of Condensed Matter Physics and Materials Science, Brookhaven National Laboratory
    • Brookhaven National Laboratory
    • CMPMSD, Brookhaven National Laboratory
    • 2Condensed Matter Physics and Materials Science Departement, Brookhaven National Laboratory

  • Fei Han

    • Nuclear Engineering, Massachusetts Institute of Technology
    • Massachusetts Institute of Technology
    • Department of Nuclear Science and Engineering, Massachusetts Institute of Technology

  • Mingda Li

    • Massachusetts Institute of Technology
    • Nuclear Engineering, Massachusetts Institute of Technology
    • Department of Nuclear Science and Engineering, Massachusetts Institute of Technology
    • Nuclear Science and Engineering, Massachusetts Institute of Technology