Optical Characterization of Few-Layer Ferromagnetic Insulator Chromium(III) Iodide Crystals

ORAL

Abstract

Van der Waals heterostructures of layered 2D materials have been widely explored for the combination of conductors, semiconductors, and insulators. However, there has been little development of magnetic 2D crystalline layers, which could lead to interesting new physical states when coupled with other atomically thin materials. Thus, we have expanded this field through the study of an insulating ferromagnetic layered material: chromium(III) iodide. We have optimized the growth and characterized the crystal structure of the bulk crystals. Moreover, we have successfully exfoliated few-layer flakes down to the monolayer. In light of their sensitivity to ambient moisture, we have also developed the necessary techniques to assure the integrity of the flakes during their manipulation. The characterization via optical contrast data and Raman spectroscopy as a function of flake thickness allows for the reliable identification of few-layer samples. In particular, we have constructed models based on Fresnel's laws to quantify the number of layers of exfoliated flakes from their optical contrast values.

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Authors

  • Dahlia Klein

    Massachusetts Institute of Technology

  • Efrén Navarro-Moratalla

    Massachusetts Institute of Technology, Massachuusetts Institute of Technology, MIT

  • Kyle Seyler

    Univ of Washington, University of Washington

  • Daniel Larson

    Harvard University

  • Efthimios Kaxiras

    Harvard University, Department of Physics, Harvard University, United States.

  • Xiaodong Xu

    University of Wasington, University of Washington, Univ of Washington, Department of Physics, University of Washington, University of Washington, Seattle, USA.

  • Pablo Jarrilo-Herrero

    Massachusetts Institute of Technology, USA, Massachusetts Institute of Thechnology, Massachusetts Inst of Tech-MIT, Massachusetts Institute of Technology, MIT