| 报告题目 | Nematic quantum paramagnet in spin-1 square lattice models: possible application to FeSe |
| 报告人 | Prof. WANG Fa |
| 报告人单位 | ICQM, the School of Physics,Peking University |
| 报告时间 | 2015-10-29 |
| 报告地点 | 合肥微尺度物质科学国家实验室九楼会议室（9004） |
| 主办单位 | 合肥微尺度物质科学国家实验室、国际功能材料量子设计中心（ICQD） |
| 报告介绍 | 报告摘要：
For spin-1/2 systems when quantum fluctuations destroy the Neel long-range order and open a spin gap, the resulting state usually breaks the lattice translation and rotation symmetries. This can be understood as reflecting a Berry's phase associated with the magnetic monopole of the Neel order parameter. Here we point out the same Berry phase causes spin-1 systems to spontaneously break the discrete rotational symmetry of the crystal while preserving its translation symmetry. We support this claim by presenting an exactly solvable microscopic model whose ground state is a nematic quantum paramagnet. In addition we derive a field theory to describe the continuous, Landau-forbidden phase transition between a Neel ordered state and a nematic quantum paramagnet, and compare the theory with existing numerical results. We propose that the nematic quantum paramagnetic state captures essential features of bulk FeSe which becomes nematic around 90K but does not develop any spin long range order down to the lowest measured temperature. 报告人简介： |
