APS Logo

Spin-orbit coupling, exchange, and magnetism in exciton physics of 2D semiconductors

Invited

Abstract

Interactions (e.g., spin-orbit coupling (SOC), electron-hole (e-h), magnetic ordering, etc.) often give rise to dramatic new features in the photophysics of 2D materials. With newly developed full-spinor ab initio GW & Bethe-Salpeter equation (GW-BSE) methods, we investigate the interplay among these interactions in 2D semiconductors. We discover that e-h exchange interaction in monolayer transition metal dichalcogenides mixes the well-known A and B excitons that heretofore were believed to be completely independent of each other, since A and B excitons had been viewed as derived from inter-band transitions between different pairs of spin-polarized bands [1]. In another study, we elucidate the physical origin of giant excitonic and magneto-optical responses in monolayer CrI3, a prototypical 2D ferromagnetic semiconductor [2]. Our calculations demonstrate that the optical properties of ferromagnetic monolayer CrI3 are dominated by exciton states that extend over several unit cells. By simulating a realistic experimental setup, we further predict a strong dependence of magneto-optical Kerr effect signals on excitation frequency and substrate configuration.

[1] L. Guo, M. Wu, T. Cao, D. M. Monahan, Y.-H. Lee, S. G. Louie, and G. R. Fleming, “Exchange-driven intravalley mixing of excitons in monolayer transition metal dichalcogenides” Nat. Phys. 15, 228 (2019).
[2] M. Wu, Z. Li, T. Cao, and S. G. Louie, “Physical origin of giant excitonic and magneto-optical responses in two-dimensional ferromagnetic insulators,” Nat. Commun. 10, 2371 (2019).

–

Presenters

  • Meng Wu

    University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory

Authors

  • Meng Wu

    University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory

  • Zhenglu Li

    Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, C, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory

  • Ting Cao

    University of Washington, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory, Physics, University of Washington, Department of Materials Science and Engineering, University of Washington and Geballe Laboratory for Advanced Materials, Stanford University

  • Steven Louie

    University of California at Berkeley, and Lawrence Berkeley National Laboratory, Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, C, University of California, Berkeley, Department of Physics, University of California, Berkeley, Lawrence Berkeley National Laboratory and University of California at Berkeley, Department of Physics, University of California at Berkeley and Lawrence Berkeley National Laboratory, Department of Physics, UC Berkeley, Physics, Unviersyt of Calfornia, Berkeley, Physics, University of California, Berkeley, Physics, University of California, Berkeley and Lawrence Berkeley National Lab