Ligand-field Helical Luminescence in a 2D Magnetic Insulator

ORAL · Invited

Abstract

Bulk chromium triiodide (CrI3) has long been known as a layered van der Waals ferromagnet. However, its monolayer form was only recently isolated and confirmed to be a truly two-dimensional (2D) ferromagnet, providing a new platform for investigating light-matter interactions and magneto-optical phenomena in the atomically thin limit. Here, we report spontaneous circularly polarized photoluminescence in monolayer CrI3 under linearly polarized excitation, with helicity determined by the monolayer magnetization direction. In contrast, the bilayer CrI3 photoluminescence exhibits vanishing circular polarization, supporting the recently uncovered anomalous antiferromagnetic interlayer coupling in CrI3 bilayers. Distinct from the Wannier-Mott excitons that dominate the optical response in well-known 2D van der Waals semiconductors, our absorption and layer-dependent photoluminescence measurements reveal the importance of ligand-field and charge-transfer transitions to the optoelectronic response of atomically thin CrI3. We attribute the photoluminescence to a parity-forbidden d-d transition characteristic of Cr3+ complexes, which displays broad linewidth due to strong vibronic coupling and thickness-independent peak energy due to its localized molecular orbital nature.

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Presenters

  • Kyle Seyler

    University of Washington

Authors

  • Kyle Seyler

    University of Washington

  • Ding Zhong

    University of Washington

  • Dahlia Klein

    Massachusetts Inst of Tech-MIT, Massachusetts Institute of Technology

  • Shiyuan Gao

    Physics, Washington University in St. Louis, Washington University in St Louis, Physics, Washington University

  • Xiaoou Zhang

    Carnegie Mellon University

  • Bevin Huang

    Univ of Washington, Physics, Univ of Washington, University of Washington

  • Efren Navarro-Moratalla

    Massachusetts Institute of Technology, Instituto de Ciencia Molecular, Universidad de Valencia

  • Li Yang

    Physics, Washington University in St. Louis, Department of Physics, Washington University in St.louis, Washington University in St Louis, Physics, Washington University

  • David Cobden

    Univ of Washington, Department of Physics, University of Washington, University of Washington, Physics, University of Washington

  • Michael McGuire

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

  • Wang Yao

    Department of Physics, University of Hong Kong, Hong Kong University, University of Hong Kong, The University of Hong Kong, Department of Physics and Center of Theoretical and Computational Physics, University of Hong Kong

  • Di Xiao

    Carnegie Mellon University, Physics department, Carnegie Mellon University, Department of Physics, Carnegie Mellon University, Carnegie Mellon Univ

  • Pablo Jarillo-Herrero

    Massachusetts Inst of Tech-MIT, Department of Physics, Massachusetts Institute of Technology, Physics, MIT, MIT, Massachusetts Institute of Technology

  • Xiaodong Xu

    University of Washington, Materials Science and Engineering, University of Washington