题目：Identifying Quantum States by High-pressure NMR in Strongly Correlated Electron Systems

报告人：Weiqiang Yu  Renmin University

地点： 教十二-201

时间： 6月23日，周五，15:00-16:00

摘要：

Strong electron correlations produce rich and novel quantum states. Nuclear magnetic resonance (NMR), utilizing the quantum spin and/or quadrupolar moments of the nuclei, is a powerful local probe to detect various quantum states and low-energy spin fluctuations in strongly correlated electron systems.

In this talk, I will focus on our recent high-pressure NMR studies on two classes of materials. In some iron-based high-temperature superconductors, we have found evidences for charge ordering [1], resolved an intrinsic magnetic structure [2], and established the existence of high-temperature short-range-ordered nematicity [3]. In a Mott system -RuCl3 which was proposed to have proximate Kitaev spin-liquid behaviors, we have found that its magnetic structure can be suppressed either by magnetic field or by pressure, resulting a gapless spin-liquid-like phase [4] and a valence-bond-solid-like phase [5] respectively. The existence of these novel quantum states reveals the interplays among spin, charge, orbital, and lattice degrees of freedom.

References:

[1] P. S. Wang et al., PRB 93, 085129 (2016);

[2] P. S. Wang et al., PRL 117, 237001 (2016);

[3] P. S. Wang et al., arXiv:1705.06395 (2017);

[4] J. Zheng et al., arXiv: 1703.08474 (2017);

[5] Y. Cui et al., arXiv: arXiv:1706.02697 (2017).

个人简介：

于伟强，中国人民大学物理系教授。2004年获得UCLA博士学位，2004-2008年先后在马里兰大学、马克马斯特大学做博士后，2008年起任现职。2011年获得首届国家基金委优青资助。目前共发表60多篇学术论文。回国后主要使用固体核磁共振，并结合极低温、高压技术，专注于高温超导材料和量子磁性的物性研究，在铁基高温超导材料的磁结构、超导电性、磁性和超导的关联，自旋液体和自旋阻挫材料的量子相变和低能元激发等方面做出多项前沿研究成果。

欢迎老师和同学参加！