Condensed Matter Seminar "Fractal structures in the phase diagram of the honeycomb-lattice quantum dimer model"

Thursday, December 7, 2017 - 11:30am

Thomas Barthel (Duke University)

Quantum dimer models appear in different contexts when describing dynamics in constrained low-energy manifolds, such as for frustrated Ising models in weak transverse fields or Heisenberg magnets with quantum disordered ground states. In this talk, I address a particularly interesting case, where a quantum dimer model on the honeycomb lattice, in addition to the standard Rokhsar-Kivelson Hamiltonian, includes a competing potential term, counting dimer-free hexagons. It has a rich phase diagram that comprises a cascade of rapidly changing flux quantum numbers. Here, the flux corresponds to the average tilt in the height representation of the model. The cascade of phase transitions is partially of fractal nature ("devil's staircase") and the model provides, in particular, a microscopic realization for the Cantor deconfinement scenario. We have studied the system by means of quantum Monte Carlo simulations and the results can be explained using perturbation theory, RG, and variational arguments in terms of string configurations.[1] E. Fradkin, D. A. Huse, R. Moessner, V. Oganesyan, S. L. Sondhi, PRB 69, 224415 (2004)[2] T. M. Schlittler, T. Barthel, G. Misguich, J. Vidal, R. Mosseri, PRL 115, 217202 (2015)[3] T. M. Schlittler, R. Mosseri, T. Barthel, PRB 96, 195142 (2017)

Physics 298

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