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题目：A new effective gauge field theory of quantum spin liquids

时间：2018年7月3日（周二）下午3：00

地点：格致楼4022

摘要：

Effective gauge theories based on slave particle construction are widely used in the study of strongly correlated electron systems such as the quantum spin liquids, high-Tc superconductors, and fractional quantum Hall systems, in which emergent gauge field and fractionalized excitations play a central role in the low energy physics. A long standing issue in such effective gauge theories is the fate of the slave particle in the background of strongly fluctuating gauge field and the relation between the slave particles and the physical fractionalized excitations. Here I show that the conventional Gaussian effective gauge theory of the quantum spin liquids is unreliable. In particular, the T^{2/3} specific heat anomaly predicted by the Gaussian effective gauge theory for a gapless U(1) spin liquid with a large spinon Fermi surface is actually an artifact of the Gaussian approximation. A new approach to derive the correct low energy effective theory of the quantum spin liquids is established, which will find broad application in the study of other strongly correlated electron systems. At the same time, an unified mechanism for spin fractionalization in one and two dimensional spin liquids is proposed based on projective construction of fractionalized excitations.

个人简介

李涛，中国人民大学物理系教授。1996年在中国科大物理系获得本科、硕士学位，1999年在北大物理系获得博士学位。1999-2005年在清华大学高等研究中心工作，2005年至今在中国人民大学物理系工作。主要从事高温超导微观机理和量子磁性的理论研究。发展了基于共振价键图像的高温超导和量子磁性体系的基态和激发态的变分理论、数值算法以及这些强关联体系的低能有效场论，同时对于高温超导的赝能隙现象开展了系列唯象理论研究。