講演題目: Deterministic domain switching and magnetically switchable quantum geometric photocurrents in a Van der Waals antiferromagnet
講師: Liang Wu 氏（University of Pennsylvania）
日時: 2026年8月20日(木) 10:30～11:30
場所: 北海道大学工学部アカデミックラウンジ3
要旨:
Antiferromagnets (AFMs) have also attracted enormous interest recently in spintronics due to the absence of stray fields and their terahertz resonant frequency. Despite the great advantages of antiferromagnetic spintronics, controlling and directly detecting antiferromagnetic order and other emergent order in 2D materials have been challenging. In my talk, I will focus on the Neel order in 2D AFM MnPSe3. I will show that we have developed a sensitive second harmonic generation (SHG) microscope and detected long-range Neel antiferromagnetic (AFM) order down to the monolayer in MnPSe3. We also observed the deterministic switching of 180-degree AFM domain in this compound. Finally, magnetic crystals have been predicted to show a new set of hitherto unobserved magnetically switchable photocurrents, with the roles of linear and circular light interchanged: A linear injection current, which probes the quantum metric, and circular shift current, which probes the geometric torsion. I will present the existence of such currents in MnPSe3, demonstrating the switching of the current by flipping the Néel vector deterministically.
REFERENCES:
Ni et al. Phys. Rev. Lett. 127, 187201 (2021)
Ni et al. Nature Nanotechnology 16, 782-787 (2021)
Ni et al. arxiv.2404.06010 ; arXiv:2407.20222
Tian, Ni et al. arXiv:2605.22518