Raman spectroscopy of CrSiTe$_{\mathrm{3}}$ multilayers

ORAL

Abstract

Ferromagnetism in two-dimensional (2-D) single crystals is a hypothesis under intense scrutiny by theorists and experimentalists alike seeking to model and realize it, respectively. Derived from an intrinsically ferromagnetic bulk compound composed of weakly coupled layers, 2-D CrSiTe$_{\mathrm{3}}$ is an ideal candidate for such a study. Here we correlate the thicknesses of various CrSiTe$_{\mathrm{3}}$ multilayers to their Raman spectra, accounting for the degradative effects of oxidation by fabricating devices and performing measurements in a chemically inert atmosphere. We then passivate the surfaces via encapsulation with hexagonal boron nitride (hBN) before repeating the experiments in air. Our results explain the absence of predicted phonon modes in the few-layer limit of CrSiTe$_{\mathrm{3}}$ as previously observed in the literature and, more importantly, offer a reliable method of identifying the CrSiTe$_{\mathrm{3}}$ monolayers that may potentially settle the debate over ferromagnetic order in reduced dimensionalities.

*NSF IGERT (DGE-1069240)

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Authors

  • Dennis Wang

    • Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA

  • David Mandrus

    • The University of Tennessee, Knoxville
    • Department of Materials Science and Engineering, University of Tennessee, Knoxville, Knoxville, Tennessee 37996, USA
    • Oak Ridge National Laboratory \& University of Tennessee
    • University of Tennessee, Knoxville
    • Department of Materials Science and Engineering, University of Tennessee

  • Abhay Pasupathy

    • Columbia University
    • Department of Physics, Columbia University, New York, New York 10027, USA
    • Physics Department, Columbia University, New York, USA

  • Irving Herman

    • Department of Applied physics and Applied Mathematics, Columbia University
    • Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
    • Department of Applied Physics, Columbia University, New York, USA