Seminar
Tuesday, 27 April, 2010
Group seminar MPQ: Spin-Liquid Phase in the Hubbard Model on the Honeycomb Lattice
Ziyang Meng, Institut für Theoretische Physik III, Universität Stuttgart
Tuesday, 27.04.2010 10 a.m. (s.t.) in Herbert-Walther-lecture room, MPQ Garching
The Hubbard model encapsulates the physics of strongly correlated quantum systems in its most basic form. It has been studied intensively in the context of the high-temperature superconductivity. A number of novel phases were recently proposed for Hubbard-like models on the honeycomb lattice, the sturecture of graphene. We analyzed the Hubbard model of spin-1/2 fermions on the honeycomb lattice at half-filling using large-scale quantum Monte Carlo simulations. We find that the weak coupling semimetal and the antiferromagnetic Mott insulator at strong interaction are separated by an extended gapped phase in an intermediate coupling regime. Exploring excitation gaps, various correlation functions as well as probing for flux quantization, we conclude that a quantum spin liquid, lacking any conventional order, emerges with local charge and spin correlations, best described by a resonating valence bonds.