title: Diagnosis of Interaction-driven Topological Phase via Exact Diagonalization.
abstract: We propose a general scheme for diagnosing interaction-driven topological phases in the weak interaction regime using exact diagonalization (ED). The scheme comprises the analysis of eigenvalues of the point-group operators for the many-body eigenstates and the correlation functions for physical observables to extract the symmetries of the order parameters and the topological numbers of the underlying ground states at the thermodynamic limit from a relatively small size system afforded by ED. As a concrete example, we investigate the interaction effects on the half-filled spinless fermions on the checkerboard lattice with a quadratic band crossing point. Numerical results support the existence of a spontaneous quantum anomalous Hall phase purely driven by a nearest-neighbor weak repulsive interaction, separated from a nematic Mott insulator phase at strong repulsive interaction by a first-order phase transition.
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, China.
authors.forename: Han-Qing
authors.initials: HQ
authors.lastname: Wu
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, China.
authors.forename: Yuan-Yao
authors.initials: YY
authors.lastname: He
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Fang
authors.affiliation: Beijing National Laboratory for Condensed Matter Physics, and Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Zi Yang
authors.initials: ZY
authors.lastname: Meng
authors.affiliation: Department of Physics, Renmin University of China, Beijing 100872, China.
authors.forename: Zhong-Yi
authors.initials: ZY
authors.lastname: Lu