Title: Quantum critical dynamics for a prototype class of insulating antiferromagnets

Speaker: Prof. Jianda Wu (吴建达)

Affiliation: Tsung-Dao Lee Institute at Shanghai Jiao TongUniversity（上海交通大学李政道研究所）

Time: 09:30-11:30, Monday, 26th June, 2023 (UTC+8, Beijing Time)

Venue: Room 1502, Yifu Architecture Building, Sipailou Campus of Southeast University, Nanjing

   （东南大学四牌楼校区逸夫建筑馆丘成桐中心1502室）

Inviter: Yunfeng Jiang（江云峰）

Abstract  

Quantum criticality is a fundamental organizing principle for studying strongly correlated systems. Nevertheless, understanding quantum critical dynamics at nonzero temperatures is a major challenge of condensed-matter physics due to the intricate interplay between quantum and thermal fluctuations. The recent experiments with the quantum spin dimer material TlCuCl3 provide an unprecedented opportunity to test the theories of quantum criticality. We investigate the nonzero-temperature quantum critical spin dynamics by employing an effective O(N) field theory. The on-shell mass and the damping rate of quantum critical spin excitations as functions of temperature are calculated based on the renormalized coupling strength and are in excellent agreement with experiment observations. Their T ln T dependence is predicted to be dominant at very low temperatures, which will be tested in future experiments. Our work provides confidence that quantum criticality as a theoretical framework, which is being considered in so many different contexts of condensed-matter physics and beyond, is indeed grounded in materials and experiments accurately. It is also expected to motivate further experimental investigations on the applicability of the field theory to related quantum critical systems.

[1] J. Wu, W. Yang, C. Wu, and Q. Si, Phys. Rev. B 97, 224405 (2018).

Speaker

Prof. Jianda Wu has long been committed to the research work in quantum phase transitions, quantum critical thermodynamics and dynamics, Bethe ansatz, and dynamics in quantum integrable systems. He obtained BS (2004) and MS (2007) degrees from University of Science and Technology of China, and got PhD (2014) from Rice University. From 2014-2017 he carried out postdoc research at University of California at San Diego, then (2017-2018) became a guest scientist at Max Planck Institute for the Physics of Complex Systems. Since 2018 he became a Tsung-Dao Lee Fellow at Tsung-Dao Lee Institute and a faculty member at School of Physics and Astronomy at Shanghai Jiao Tong University. Prof. Wu has published 29 papers with 10 papers appear on Nature, Nature Physics, Nature Communications, and Phys. Rev. Lett. So far, he has delivered more than 40 invited talks at international conferences/workshops, and universities and institutes around the world.

吴建达，李政道学者。长期致力于量子相变、量子临界热力学及动力学、贝特拟设及可积系统动力学等相关领域的研究工作。2004年及2007年于中国科学技术大学获得学士及硕士学位、2014年博士毕业于美国莱斯大学、2014-2017年在美国加州大学圣地亚哥分校从事博士后工作、2017-2018年担任德国马普复杂系统物理所客座研究员。2018年至今就职于上海交通大学李政道研究所及物理与天文学院。迄今已在包括PRL、Nature及Nature子刊等在内的高水平学术期刊上共发表论文29篇。先后在国际及国内重要学术会议、国内外科研机构及学术单位给邀请学术报告四十余次。