摘要：
Dipolar interactions—ubiquitous in anisotropic magnetic systems with local moments—can dominate over exchange interactions and profoundly reshape material behavior. Their long-range, anisotropic nature enhances magnetic frustration and may stabilize exotic emergent phenomena. In this talk, we explore dipolar effects through two complementary aspects.

First, in pyrochlore quantum spin ices with dipole-octupole doublets, we examine how symmetry-enriched U(1) topological orders in Ce pyrochlore magnets may exhibit distinct experimental signatures in the classical limit: long-range dipolar interactions can endow monopoles in the dipolar spin liquid with a finite magnetic charge, while in octupolar spin liquid monopoles show vanishing magnetic charge. This perspective offers potential resolution to debates on materials like Ce₂Sn₂O₇ and informs studies of Ce/Nd pyrochlores and Er spinels. Second, in quantum regimes, we investigate how dipolar interactions on frustrated kagome lattices may support intrinsic Z₂ topological order. Described by a Z₂ lattice gauge theory, this phase hosts fractional spinon and vison excitations, with thermodynamic and spectroscopic signatures suggesting pathways for detection in systems from polar molecule simulators to rare-earth magnets such as tripod kagome materials. To summarize, these insights point to universal principles governing topological orders across energy scales, proposing anisotropic interactions on frustrated geometries as promising components for exotic emergent phenomena. This framework encourages further exploration of anisotropic magnetism in unexplored materials and quantum simulators.

References:
[1] Pengwei Zhao, Gang Chen, SciPost Phys 19, 040 (2025).  
[2] Pengwei Zhao, Gang Chen, arXiv:2505.07805 (2025).
[3] Yaodong Li, Gang Chen, PhysRevB 95, 041106 (2017).
[4] Gang Chen, PhysRevResearch 5, 033169 (2023).

报告人简介：
现任北京大学国际量子材料中心博雅特聘教授，曾在香港大学担任教授。在University of California Santa Barbara获博士学位，师从Kavli理论物理研究所Leon Balents院士。研究领域主要是强关联多体理论，在量子磁性、关联电子、巡游阻挫、拓扑材料、介观物理学以及超冷原子等领域发表100余篇论文，并在培养学生和博后方面有一定的积累。2016年获崔琦Fellow，2018年获求是杰出青年学者奖。