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.

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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