IEEE Magnetics Society and HKUST ECE Joint Distinguished Seminar - THz Spin Resonance and Magnon Currents in Antiferromagnetic Heterostructures

2:00pm - 3:30pm
Classroom 6573 (via Lifts 29/30)

Magnons, the quasiparticles of spin waves, are the elementary low-energy collective excitations in magnetic materials. Antiferromagnetic insulators (AFMIs) can host THz frequency magnons to carry angular momentum without moving charges [1], however not much is known about the propagation of magnons in antiferromagnetic materials so far. We first detect THz spin resonance in an antiferromagnetic materials such as NiO [2] and Fe2O3 [3]. Using current injection in antiferromagnetic heterostructures with a heavy metal, we manipulate the magnon frequency, enabling high-speed and low-dissipation operation of spin devices [2,4]. The magnon propagation speed, which is a key parameter to determine data operation time, remains elusive in AFMIs, particularly at nanometer distances due to the lack of sufficiently fast probes. Using the direct time-domain measurement of the velocity of antiferromagnetic magnons in NiO, we find the magnons propagate in NiO at a superluminal velocity up to 650 km/s [5]. Our observation suggests the prospects of energy-efficient nanodevices using AFMIs considering finite dissipation in real materials.

[1] Wang, Y. et al., Science 366, 1125 (2019); [2] Yang, D. et al., Phys. Rev. Applied. 20, 014023 (2023); [3] Liu, Q. et al., Adv. Funct. Mater. 2305173 (2023); [4] Yang, D. et al., Nat. Comm. 15, 4046 (2024); [5] Lee, K. et al., Nat. Nanotechnol. 16, 1337 (2021)

講者/ 表演者:
Prof. Hyunsoon Yang
ECE, National University of Singapore

Hyunsoo Yang is a Professor in the Department of Electrical and Computer Engineering, National University of Singapore (NUS), working on various magnetic materials and devices for spintronics applications. He worked at C&S technology and Intelligent Fiber Optic Systems, California. He received his Doctorate from Stanford University. From 2004-2007, he was at IBM Almaden Research Center. He has authored more than 250 journal articles, given 200 invited presentations, and 20 patents. He was a recipient of the Outstanding Dissertation Award for 2006 from the American Physical Society (GMAG), an IEEE Magnetics Society Distinguished Lecturer for 2019, and the Minister of Science ICT award for 2020.