Deterministic Domain Switching and Magnetically Switchable Quantum Geometric Photocurrents in a Van der Waals Antiferromagnet by Prof Liang Wu

Join us at this seminar by Prof Liang Wu from the University of Pennsylvania. This seminar is organised as part of the IAS Frontiers Seminars: Quantum Horizons, jointly supported by the Institute of Advanced Studies (IAS) and School of Physical and Mathematical Sciences (SPMS).

About the seminar

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.

About the speaker

Liang Wu got his Bachelor of Science in Physics from Nanjing University in 2010 and PhD in Physics at Johns Hopkins University in 2015. He was a postdoc fellow at University of California, Berkeley from 2016 to 2018. He joined the department of Physics and Astronomy at the University of Pennsylvania in 2018, and he is an associate professor now. He has been using terahertz spectroscopy and ultrafast optics to study topological materials,  quantum antiferromagnets, and Kagome metals. He has given over 150 invited talks on these topics.  He received several honors including the Army Research Office  Presidential Early Career Award for Scientists and Engineers  (Army PECASE),  the DOE Early Career Research Program Award, Sloan Fellowship, and the William L. McMillan Award for outstanding contributions in condensed matter physics.