【Date and Time】14-April-2026 10:30 (Beijing time)

【Venue】Room 320

【Host】Qihua Xiong (BAQIS&Tsinghua Univ.)

【Title】 Excitons and magnons in van der Waals antiferromagnet CrSBr

【Speaker】 

Mikhail Glazov is a condensed matter theorist specializing in two-dimensional materials, semiconductor spintronics, and the physics of excitons. Mikhail obtained his PhD from Ioffe Institute in 2008. Currently, he is the Principal Scientific Researcher at the Ioffe Institute and is the Deputy Chair of the Ioffe Institute's joint department at the National Research University Higher School of Economics. Additionally, Professor Glazov holds the Chair of Condensed Matter Physics at the Academic University in St. Petersburg, Russia. He was elected as a Corresponding Member of the Russian Academy of Sciences (RAS). He has been honored with the Medal of the Russian Academy of Sciences for Young Researchers, as well as the Euler Prize awarded by the St. Petersburg Government and the St. Petersburg Scientific Center of the RAS.

【Abstract】

Among great variety of van der Waals materials, CrSBr has a special place as an A-type layered antiferromagnet. The Cr spins are ferromagnetically ordered in the planes of this crystal, with the magnetization direction (along the crystallographic b-axis) alternating from layer to layer stacked along the crystallographic c-axis. The Néel temperature of this material is about 130 K [1]. CrSBr is a direct-gap semiconductor with a bandgap of approximately 1.8 eV, it exhibits strong excitonic and exciton-polaritonic effects [2]. Hence, CrSBr is an excellent platform for studying interplay of magnetic and electronic excitations.

In my talk I will provide an overview of both known and original results on studies Coulomb complexes—excitons and trions—in CrSBr and their interaction with the magnetic system. An exciton is a two-particle, electron and hole, bound state, an elementary excitation of a semiconductor. A trion is a three particle bound state where additional charge carrier, electron or hole, attaches to the exciton. Calculations of the binding energies of intralayer and interlayer excitons and trions are presented, and the manifestations of these quasiparticles in the optical spectra of CrSBr bilayers are discussed [3,4].

Magnons are elementary excitations of magnetic materials. The spectrum of magnons in CrSBr is calculated with account for the short-range exchange and long-range dipole-dipole interactions. Within the framework of the orbital mechanism of exciton–magnon interaction, a theory of the joint propagation of excitons and magnons in CrSBr is developed, and experiments on exciton transport in this system are described [5,6]. We demonstrate efficient drag of excitons by magnons and a number of nonlinear transport phenomana stemming from specifics of quasiparticles dispersion and interactions.

[1] N. P. Wilson, et al, Interlayer electronic coupling on demand in a 2D magnetic semiconductor, Nature Materials 20, 1657 (2021).

[2] F. Dirnberger, et al., Magneto-optics in a van der Waals magnet tuned by self-hybridized polaritons, Nature 620, 533 (2023).

[3] F. Tabataba-Vakili, et al., Doping-control of excitons and magnetism in few-layer CrSBr, Nat. Communs. 15, 4735 (2024).

[4] M. A. Semina, et al., Excitons and trions in CrSBr bilayers, Phys. Rev. B 111, 205301 (2025).

[5] F. Dirnberger, S. Terres, Z. A. Iakovlev, et al., Exciton transport driven by spin excitations in an antiferromagnet, Nature Nanotechnology 21, 65-70 (2026) https://doi.org/10.1038/s41565-025-02068-y

[6] Z. A. Iakovlev, A. Kamra, M. M. Glazov, Boltzmann transport theory of magnon-exciton drag, arXiv:2512.05835 (2025) https://arxiv.org/abs/2512.05835