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Exploring van der Waals Ferromagnetism: Early Perspectives and Puzzles
Speaker Prof. Maciej Koperski, National University of Singapore
Date 22 May 2024 (Wednesday)
Time 15:00 - 16:30
Venue Room 5583, Academic Building, HKUST (Lifts 27-28)

The preservation of ferromagnetism in monolayer films of van der Waals magnets was demonstrated recently. It enabled us to explore the effects of spin dimensionality on the magnetic states in materials through a diverse repertoire of experimental methods enabled by van der Waals technology [1]. A rapidly growing body of work inspecting magnetic, optoelectronic, structural, or vibrational properties of heterostructures and devices inspires us to search for novel physical phenomena, excitations, and magnetic/topological states originating from or coupled to the two-dimensional magnetic order. I will present early perspectives and numerous puzzles yet to be addressed based on our recent results on exciton-magnetization coupling [2], the emergence of topological spin textures in insulating van der Waals ferromagnets [3], and heterostructures interfacing ferromagnets with monolayer semiconductors [4].


Dr. Maciej Koperski is an Assistant Professor at the Materials Science and Engineering Department and a Principal Investigator at the Institute for Functional Intelligent Materials at the National University of Singapore. He is a condensed matter physicist focused on the investigations of the light-matter interactions at the nanoscale. The research topics include excitonic physics in semiconductors, single photon emitters, the functionality of defect centers in wide-bandgap materials, and ferromagnetism in low-dimensional structures.


[1] M. Gibertini, M. Koperski, A. F. Morpurgo, K. S. Novoselov, Magnetic 2D materials and heterostructures, Nature Nanotechnology 14 (5), 408-419 (2019).
[2] M. Grzeszczyk, S. Acharya, D. Pashov, Z. Chen, K. Vaklinova, M. van Schilfgaarde, K. Watanabe, T. Taniguchi, K. S. Novoselov, M. I. Katsnelson, M. Koperski, Strongly Correlated Exciton‐Magnetization System for Optical Spin Pumping in CrBr3 and CrI3, Advanced Materials 35 (17), 2209513 (2023)
[3] S. Grebenchuk, C. McKeever, M. Grzeszczyk, Z. Chen, M. Šiškins, A. R. C. McCray, Y. Li, A. K. Petford‐Long, C. M. Phatak, D. Ruihuan, L. Zheng, K. S. Novoselov, E. J. G. Santos, M. Koperski, Topological spin textures in an insulating van der Waals ferromagnet, Advanced Materials, 2311949 (2024).
[4] Ł. Kipczak, Z. Chen, P. Huang, K. Vaklinova, K. Watanabe, T. Taniguchi, A. Babiński, M. Koperski, M. R. Molas, Multidimensional sensing of proximity magnetic fields via intrinsic activation of dark excitons in WSe2/CrCl3 heterostructure, arXiv:2304.11896 (2023).

Please contact phweb@ust.hk should you have questions about the talk.