报告题目：Novel propertiesdue to crystal symmetry in spin-splitting antiferromagnet and topologicalsuperconductor
报告人：刘军伟教授（香港科技大学物理系）
主持人：赵宇军教授
报告时间：2025年3月3日（星期一）10:00
报告地点：物理楼（18号楼）二楼213室学术报告厅
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物理与光电学院
2025年2月24日
附件：
内容摘要：I will talk about the novel properties due to crystal symmetryspin-splitting antiferromagnets (AFMs) [Nat. Commun. 12, 2846 (2021)] (named asaltermagnet in 2022) and in topological superconductor [Nature 633, 71 (2024)].
Inspin-splitting AFMs, we propose the crystal-symmetry-pairedspin-valley/momentum locking (CSVL/CSML), which is enabled by a crystalsymmetry and intrinsically exists in AFMs (e.g., V2Se2O, V2Te2O, MnTe and RuO2)[Nat. Commun. 12, 2846 (2021)]. CSML enables feasible controls of spin in AFMsby manipulating the corresponding crystal symmetry. Typically, one can use astrain field to induce net valley polarization/magnetization and use anelectric field to generate a noncollinear spin current even without spin-orbitcoupling. All the predictions have been confirmed in experiments[arXiv:2407.19555; arXiv:2408.00320 (both accepted in Nature Physics)]. Theseproperties have helped us realize the electric readout and 180o deterministicswitching of the Néel order in our experimental work in Mn5Si3 [Sci. Adv. 10, eadn0479(2024)] and CrSb [Nature 638, 645–650 (2025)].
In topologicalsuperconductors, magnetic mirror symmetry can protect multiple Majorana zeromodes (MZMs) in a single vortex, which allows feasible controls ofhybridization of MZMs simply using an external field. This has been realized inour recent collaborative experimental works with Prof Jin-Feng Jia’s group [Nature 633, 71 (2024); Quantum Frontiers 3, 20 (2024)]. Similarproperties can also be realized in superconducting CSVL/CSML materials.
报告人简介： Prof. Junwei Liuobtained his PhD at Tsinghua University in 2014 and then did his postdoctoralresearch at MIT. He joined HKUST in 2017 as an assistant professor and waspromoted to an associate professor in 2023.
He has a broad interest in condensedmatter physics, quantum physics and materials science. His major contributionsinclude (1) theoretical prediction of SnTe-type topological crystallineinsulator, WTe2-type and TaIrTe4-type quantum spin Hallinsulator; (2) discovery of world-first monolayer ferroelectricity in SnTe thinfilms; (3) proposal of self-learning Monte Carlo methods that can be thousandsof times faster than conventional methods without loss of any accuracy; (4)design and realization of the world-first all-optical neural networks; and (5)proposal of crystal-symmetry-paired spin-valley locking and realization ofworld-first electrical readout and 180° switching of the Néel order inspin-splitting antiferromagnetic materials. He has published more than 60papers including 2 in Science, 3 in Nature, 1 in Nat. Phys., 3 in Nat. Mater.,7 in Nat. Commun., 3 in Phys. Rev. Lett., 1 in Optica, etc.
