title: Quantum spin liquid emerging in two-dimensional correlated Dirac fermions.
abstract: At sufficiently low temperatures, condensed-matter systems tend to develop order. A notable exception to this behaviour is the case of quantum spin liquids, in which quantum fluctuations prevent a transition to an ordered state down to the lowest temperatures. There have now been tentative observations of such states in some two-dimensional organic compounds, yet quantum spin liquids remain elusive in microscopic two-dimensional models that are relevant to experiments. Here we show, by means of large-scale quantum Monte Carlo simulations of correlated fermions on a honeycomb lattice (a structure realized in, for example, graphene), that a quantum spin liquid emerges between the state described by massless Dirac fermions and an antiferromagnetically ordered Mott insulator. This unexpected quantum-disordered state is found to be a short-range resonating valence-bond liquid, akin to the one proposed for high-temperature superconductors: the possibility of unconventional superconductivity through doping therefore arises in our system. We foresee the experimental realization of this model system using ultra-cold atoms, or group IV elements arranged in honeycomb lattices.
authors.affiliation: Institut für Theoretische Physik III, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany. meng@theo3.physik.uni-stuttgart.de
authors.forename: Z Y
authors.initials: ZY
authors.lastname: Meng
authors.forename: T C
authors.initials: TC
authors.lastname: Lang
authors.forename: S
authors.initials: S
authors.lastname: Wessel
authors.forename: F F
authors.initials: FF
authors.lastname: Assaad
authors.forename: A
authors.initials: A
authors.lastname: Muramatsu