The search for the exotic quantum phases constitutes one of the most important and hot issues in modern condensed matter physics. In this talk, I will first give a brief introduction to some modern quantum phases realized in low-dimensional (quasi-2D) materials and their properties. Then, I will present our recent theoretical investigations on the possible quantum phases and the quantum phase transitions realized in the Haldane-Hubbard model, and pseudogap in 5d transition metal oxide Sr2IrO4. In particular, we uncover a new topological phase transition in the Haldane-Hubbard model which is not accompanied with the single particle gap closing but is associated with the zeros of the single particle Green's function. And a non-magnetic topological Mott insulating phase with no gapless single particle edge states which cannot be adiabatically connected to any non-interacting Chern insulator.

李建新，教授，博士生导师。从事凝聚态物理的理论研究。1993年于武汉大学获博士学位。1998年至1999年台湾“中研院”物理研究所访问学者, 2006年至2007年美国加州大学伯克利分校伯克利访问学者。2004年入选教育部“新世纪优秀人才支持计划”。2005年获国家杰出青年科学基金。2008年作为团队负责人获教育部创新团队。2008年度受聘为教育部长江学者特聘教授。主要研究领域包括：1) 强关联电子系统的理论和数值计算研究；2) 非常规超导物性和机理；3) 强自旋-轨道系统中的关联量子态、拓扑量子态和量子相变。