Nematic Ferromagnetism on the Lieb Lattice  

作　　者：陈科技 张威 

机构地区：[1]Department of Physics, Renmin University of China, Beijing 100872 [2]Beijing Key Laboratory of Opto-electronic Functional Materials and Micro-nano Devices, Renmin University of China, Beijing 100872

出　　处：《Chinese Physics Letters》2014年第11期14-17,共4页中国物理快报（英文版）

基　　金：Supported by the National Natural Science Foundation of China under Grant Nos 10904172 and 11274009, the Research Funds of Renmin University of China under Grant Nos 14XNH061 and 10XNL016, and the Program of State Key Laboratory of Quantum Optics and Quantum Optics Devices under Grant No KF201404.

摘　　要：We discuss the properties of ferromagnetic orders on the Lieb lattice and show that a symmetry protected quadratic-fiat band crossing point will dramatically affect the magnetic ordering. In the presence of a weak on-site repulsive interaction, the ground state is a nematic ferromagnetic order with simultaneously broken time-reversal and rotational symmetries. When the interaction strength increases, the rotational symmetry will restore at a critical value, and the system enters a conventional ferromagnetic regime. The mean-field transition temperatures for both the nematic and conventional ferromagnetic phases are in the order of interaction. This observation suggests that these magnetic orders have the potential to be realized and detected in cold atomic systems within realistic experimental conditions.We discuss the properties of ferromagnetic orders on the Lieb lattice and show that a symmetry protected quadratic-fiat band crossing point will dramatically affect the magnetic ordering. In the presence of a weak on-site repulsive interaction, the ground state is a nematic ferromagnetic order with simultaneously broken time-reversal and rotational symmetries. When the interaction strength increases, the rotational symmetry will restore at a critical value, and the system enters a conventional ferromagnetic regime. The mean-field transition temperatures for both the nematic and conventional ferromagnetic phases are in the order of interaction. This observation suggests that these magnetic orders have the potential to be realized and detected in cold atomic systems within realistic experimental conditions.

分 类 号：O413.3[理学—理论物理] TG142.71[理学—物理]