Abstract: Under suitable conditions, some twisted graphene multilayers and transition-metal dichalcogenides become Chern insulators, exhibiting the anomalous quantum Hall effect and orbital magnetization. Our theory [1] describes the interaction of a Chern insulator with circularly polarized light. We show that the interaction energy couples the helicity of incident light to the Berry curvature of electrons. Taking advantage of this interaction, we propose optical switching of the sign of the Chern number, representing topological memory, by circularly polarized light. Moreover, two laser beams of opposite circular polarization can nucleate domains with opposite Chern numbers and thus produce an optically configurable domain wall carrying chiral edge modes [1]. Similar optical control was realized experimentally for gyrotropic order in 1T-TiSe2 [2] and for antiferromagnetic order in the topological axion insulator MnBi2Te4 [3]. We also explain the experimentally observed optical switching of magnetization in the atomically thin 2D ferromagnet CrI3 [4] using the principle of maximal entropy production.
Using the same formalism, we also show that circular stirring of an optical lattice can induce a controlled direct current of bosonic atoms loaded into the lattice [5], similarly to the circular photogalvanic effect in solid-state physics. This effect can be used to transport neutral bosonic atoms in an optical lattice over a given distance in a specified direction.
[1] S. S. Pershoguba and V. M. Yakovenko, “Optical control of topological memory based on orbital magnetization,” PRB 105, 064423 (2022); Erratum: PRB 108, 059904(E) (2023).
[2] S.-Y. Xu et al., “Spontaneous gyrotropic electronic order in a transition-metal dichalcogenide,” Nature 578, 545 (2020).
[3] J.-X. Qiu et al., “Axion optical induction of antiferromagnetic order,” Nature Materials 22, 583 (2023).
[4] P. Zhang et al., “All-optical switching of magnetization in atomically thin CrI3,” Nature Materials 21, 1373 (2022).
[5] S. S. Pershoguba and V. M. Yakovenko, “Direct current in a stirred optical lattice,” Annals of Physics 447, 169075 (2022).
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