Regensburg 2010 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 12: CE: Metal-Insulator Transition 1

TT 12.12: Vortrag

Dienstag, 23. März 2010, 12:30–12:45, H19

Quantum spin-liquid state emerging in two-dimensional correlated Dirac fermions — Zi Yang Meng¹, •Thomas C. Lang², Stefan Wessel¹, Fakher F. Assaad², and Alejandro Muramatsu¹ — ¹Institut für Theoretische Physik III, Universität Stuttgart, Germany — ²Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Germany

We analyze the ground-state of the Hubbard model of spin-1/2 Dirac 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 interactions are separated by an extended gapped phase in an intermediate coupling regime. Exploring excitation gaps, correlation functions as well as probing for flux quantization, we conclude that a spin liquid, lacking any conventional order (i.e. symmetry breaking), emerges in the vicinity of the Mott transition with local correlations best described by resonating valence bonds.