Giant excitonic and magneto-optical responses in two-dimensional ferromagnets

ORAL

Abstract

The magneto-optical (MO) effects, such as the magneto-optical Kerr effect (MOKE) and the Faraday effect, have been intensively investigated in a variety of magnetic materials serving as a highly sensitive probe for electronic and magnetic properties. Recent experiments using MOKE have discovered a few two-dimensional (2D) magnets, and demonstrated their rich magnetic behaviors. In particular, a giant Kerr response has been measured in monolayer and few-layer CrI3. However, by far, the microscopic origin of such MO signals is still unknown, because the essential spin-orbit coupling and excitonic effects are beyond the capability of existing first-principles methods. With newly developed GW and GW-BSE methods, we show that the exceedingly large optical and MO responses in ferromagnetic monolayer CrI3 arise from the strongly bound exciton states consisting of spin-polarized electron-hole states. With a realistic experimental setup, we find that the substrate configuration and excitation frequency strongly shape the MO signals. Our first-principles results are in good agreement with recent experiments on CrI3.

*This work was supported by NSF (No. DMR-1508412 and No. EFMA-1542741), and by the U.S. DOE (No. DE-AC02-05CH11231). Computational resources were provided by XSEDE and NERSC.

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Presenters

  • Meng Wu

    • University of California, Berkeley
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory

Authors

  • Meng Wu

    • University of California, Berkeley
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory

  • Zhenglu Li

    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • University of California, Berkeley

  • Ting Cao

    • Physics, UC Berkeley
    • University of California, Berkeley
    • Physics Department, UC Berkeley and Geballe Laboratory for Advanced Materials, Stanford University
    • Physics Department at UC Berkeley and Geballe Laboratory for Advanced Materials at Stanford University
    • Geballe Laboratory for Advanced Materials, Stanford University

  • Steven G. Louie

    • Physics, UC Berkeley
    • University of California, Berkeley
    • Department of Physics, University of California, Berkeley
    • Physics Department, UC Berkeley and Lawrence Berkeley National Lab
    • Department of Physics, University of California at Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory
    • Physics, University of California at Berkeley
    • University of California at Berkeley and Lawrence Berkeley National Lab
    • University of California at Berkeley and Lawrence Berkeley National Laboratory
    • Physics, University of California, Berkeley
    • UC Berkeley and Lawrence Berkeley National Lab
    • Physics, University of California - Berkeley
    • Physics and Materials Sciences, University of California at Berkeley and Lawrence Berkeley National Laboratory
    • Lawrence Berkeley National Lab and University of California, Berkeley
    • University of California - Berkeley, Lawrence Berkeley National Laboratory