各向异性ruby晶格中费米子体系的Mott相变

Mott transition of fermions in anisotropic ruby lattice

本文用哈伯德模型研究各向异性ruby晶格中费米子行为,在团簇动力学平均场理论框架内将格点模型映射为有效自洽场中的杂质模型后用连续-时间量子蒙特卡罗算法求解杂质模型.基于自洽计算的结果,用最大熵方法得到各向异性ruby晶格中具有相互作用的费米子体系的单粒子态密度和双占据数后讨论了温度(T)、相互作用(U)和各向异性参数(λ)对体系的金属-绝缘相变的影响.最后给出各向异性ruby晶格中费米子体系的温度-相互作用相图,研究结果表明,低温和弱相互作用范围体系处在金属相,而在高温和强相互作用下体系内出现Mott绝缘体相.

In this work,the Hubbard model is adopted to describe fermions with on-site repulsive interaction and the nearest-neighbor hopping in anisotropic ruby lattice.The combination of cluster dynamical mean field theory and continuous-time quantum Monte Carlo algorithm is used to solve the theoretical model.It is widely accepted that the density of states and the double occupancy are two important quantities for determining the phase transition of two-dimensional strongly correlated system.Therefore,based on the self-consistent calculation,using the maximum entropy method to calculate the single particle density of states and double occupancy of fermions in anisotropic ruby lattice.Here in this work,there are 6 sites in a cluster.The influences of temperature,interaction and anisotropic parameter on metal-insulator phase transition of fermions in anisotropic ruby lattice are discussed based on the calculations of single particle density of state and double occupancy.Finally,the metal-Mott insulator phase diagram which shows the competition between temperature and on-site repulsive interaction in the phase transition of fermions in anisotropic ruby lattice is presented.The results shows that the system is in metallic state for the regime of weak interaction and low temperature,and the Mott insulator appears in the regime of strong interaction and high temperature.The metallic state and Mott insulating one are separated by the second-order transition line in the phase diagram.