Tracking Spin and Orbital Dynamics in Magnetic Heterostructures by Spintronic Terahertz Emission Spectroscopy

by Prof. Zhensheng Tao（陶镇生） (Fudan University)

Wednesday 21 Oct 2026, 14:00 → 15:00 Asia/Shanghai

Tsung-Dao Lee Institute/N4F-N400 - meeting room (Tsung-Dao Lee Institute)

Host: Prof. Tao Dong  

Venue: TDLI Meeting Room N400

Tencent Meeting link:  https://meeting.tencent.com/dm/INCgkS8N5iL1

Meeting ID: 794670601, no password

 

 

Abstract:

Orbitronics – the generation, transport, and conversion of orbital angular momentum (OAM) – has emerged as a frontier complementing spintronics, opening new routes to high-efficiency, charge-current-free information carriers. Spintronic terahertz emission spectroscopy provides a powerful tool for probing ultrafast spin and orbital angular momentum dynamics in magnetic heterostructures. In this talk, I will present our recent efforts to disentangle spin and orbital contributions to terahertz emission and reveal their distinct transport and pumping behaviors. We find that the orbital diffusion length in heavy metals is substantially shorter than the spin diffusion length, in contrast to previous interpretations. By quantitatively separating spin- and orbital-current-induced signals, we further determine the relative efficiencies of orbital and spin pumping in 3d transition-metal ferromagnets, enabling direct comparison with microscopic theories. Finally, we identify evidence for orbital-current injection in RuO2, a candidate altermagnetic material, highlighting the importance of orbital contributions for correctly interpreting terahertz signatures associated with its unconventional magnetic order.

 

Biography:

Prof. Zhensheng Tao is a Professor of Physics at Fudan University. He received his Ph.D. from Michigan State University in 2014, where he developed ultrafast electron microscopy for studying strongly correlated materials. He then worked as a Research Associate at JILA, University of Colorado Boulder, with Prof. Margaret Murnane and Henry Kapteyn, focusing on attosecond science and ultrafast dynamics in condensed matter. In 2018, he joined Fudan University as a Professor. He is also a recipient of China's "Youth Thousand Talents" Program and the Shanghai "Oriental Scholar" Distinguished Professorship. His research focuses on ultrafast optics, attosecond science, terahertz spintronics, and probing electron dynamics in quantum materials.