Orbital magnetic susceptibility as a thermodynamic probe of band structure and quantum geometry in atomic vdW materials

by Dr Weifeng Zhi (智伟峰) (Weizmann Institute of Science)

Monday 11 May 2026, 15:00 → 16:00 Asia/Shanghai

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

Host: Prof. Haibiao Zhou  

Venue: TDLI Meeting Room N400

Tencent Meeting link: https://meeting.tencent.com/dm/3tUgrWI9TSn3 

Meeting ID: 404204829, no password

 

Abstract:

We introduce orbital magnetic susceptibility as a thermodynamic probe of band structure and quantum geometry in atomically thin van der Waals materials. Using scanning SQUID-on-tip magnetometry, we image local susceptibility in a moiré graphene system with electric-field tunability and strong electron interactions. Combined with theoretical analysis, we show that the measured susceptibility has an orbital origin and exhibits rich structure tied to key electronic features, including Lifshitz transitions and interaction effects. Importantly, orbital susceptibility encodes geometric information—such as Berry curvature, quantum metric, and orbital magnetic moment—making it an effective thermodynamic “quantum ruler” for quantum geometry, even in time-reversal-symmetric systems. At higher magnetic fields beyond the linear-response regime, the same orbital degree of freedom gives rise to strong valley polarization and an apparent insulating state at half filling that paradoxically exhibits quantum oscillations.

 

Biography:

Weifeng Zhi got his bachelor’s degree from the School of Physics, Peking University in 2023. He then joined the group of Professor Eli Zeldov in the Department of Condensed Matter Physics, Weizmann Institute of Science where got his master’s degree in physics in 2025. Currently he is a PhD student in condensed matter physics at the Weizmann Institute. His research interest focuses on nanoscale magnetic imaging in quantum materials using scanning SQUID on tip microscopy.