郭硕鸿讲座（第八十六期）（2026年4月23日11:00）：Quantum geometry in nonlinear transport and magnetizatio

主持人：王猛 教授

报告摘要：

Quantum geometry interprets the Hilbert space of quantum states and has attracted tremendous attention in the research quantum materials. In this talk, I will cover two topics on how quantum geometry can be probed by nonlinear transport and nonlinear magnetization.

In realistic materials where disorder scatterings are everywhere, how to identify the geometric effects remains a challenge. We develop a comprehensive theory for the second- and third-order nonlinear transport, by treating the geometric effects and disorder scattering on an equal footing. More importantly, we show how the geometric and disorder mechanisms could be distinguished, by deriving a scaling law that expresses the nonlinear Hall conductivity as a polynomial function of the linear longitudinal conductivity. We apply the theory to 2D materials, topological materials, and altermagnets. This theory further promotes nonlinear transport as a quantitative probe of geometric effects in quantum materials.

The Christoffel symbol is an essential quantity in Einstein’s general theory of relativity. We discover that an electric field can induce a nonlinear magnetization in quantum materials, described by the Christoffel symbol. Quite different from the previous scenarios, this orbital magnetization does not need spin-orbit coupling. We identify many 2D material candidates (e.g., BiF3, ZnI2, and Ru4Se5) that host this quantum Christoffel nonlinear magnetization. This nonlinear Christoffel magnetization can be probed by optical techniques such as magneto-optical Kerr spectroscopy. More importantly, this quantum Christoffel nonlinear magnetization gives a paradigm of how geometry dictates physics.

报告人简介：

卢海舟，兰州大学物理学学士(1998-2002)，清华大学高等研究院物理学博士(2002-2007，导师朱邦芬院士)，香港大学沈顺清教授研究组博士后(2007-2012)、研究助理教授(2012-2015)，南方科技大学副教授(2015-2018)、教授(2018-2021)、讲席教授(2021 -至今)。主要从事凝聚态物理的研究，特别是利用量子场论等方法研究拓扑物质等新物态中的电子输运等物性。获批基金委杰青并获延续支持，入选教育部长江学者特聘教授、国家一流本科课程负责人，主持科技部重点研发项目，获全球华人物理与天文学会亚洲成就奖、腾讯科学探索奖等。