Physical origin of giant excitonic and magneto-optical responses in two-dimensional ferromagnetic insulators

The recent discovery of magnetism in atomically thin layers of van der Waals crystals has created great opportunities for exploring light–matter interactions and magneto-optical phenomena in the two-dimensional limit. Optical and magneto-optical experiments have provided insights into these topics,...

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Bibliographic Details
Published in:Nature communications 2019-05, Vol.10 (1), p.2371-2371, Article 2371
Main Authors: Wu, Meng, Li, Zhenglu, Cao, Ting, Louie, Steven G.
Format: Article
Language:English
Subjects:
639/301/1019
639/301/1034
639/766/119
639/766/119/997
Bethe-Salpeter equation
Circular dichroism
Crystal structure
Crystals
Dependence
Dichroism
Energy
Ferromagnetism
First principles
Humanities and Social Sciences
Insulators
Iodine
Ligands
Magnetism
Magnets
MATERIALS SCIENCE
multidisciplinary
Optoelectronic devices
Science
Science (multidisciplinary)
Substrates
Thin films
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Summary:The recent discovery of magnetism in atomically thin layers of van der Waals crystals has created great opportunities for exploring light–matter interactions and magneto-optical phenomena in the two-dimensional limit. Optical and magneto-optical experiments have provided insights into these topics, revealing strong magnetic circular dichroism and giant Kerr signals in atomically thin ferromagnetic insulators. However, the nature of the giant magneto-optical responses and their microscopic mechanism remain unclear. Here, by performing first-principles GW and Bethe-Salpeter equation calculations, we show that excitonic effects dominate the optical and magneto-optical responses in the prototypical two-dimensional ferromagnetic insulator, CrI 3 . We simulate the Kerr and Faraday effects in realistic experimental setups, and based on which we predict the sensitive frequency- and substrate-dependence of magneto-optical responses. These findings provide physical understanding of the phenomena as well as potential design principles for engineering magneto-optical and optoelectronic devices using two-dimensional magnets. The magneto-optical (MO) effects probe the electronic and magnetic properties of a material, particularly useful for 2D magnets. Here, the authors show that the large optical and MO responses in ferromagnetic monolayer CrI 3 arise from strongly bound excitons, extending over several atoms.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-019-10325-7