1-3 August 2016
Plymouth University
Europe/London timezone
The 14th International workshop on QCD in extreme conditions, Aug. 1-3 2016

Competing order in the fermionic Hubbard model on the hexagonal graphene lattice

1 Aug 2016, 11:40
Portland Square (Plymouth University)

Portland Square

Plymouth University

Drake Circus Plymouth, Devon PL4 8AA, UK
Talk Condensed matter systems Monday AM


Prof. Lorenz von Smekal (Justus-Liebig University Giessen)


We study the phase diagram of the fermionic Hubbard model on the hexagonal lattice in the space of on-site and nearest neighbor couplings with Hybrid-Monte-Carlo simulations. With pure on-site repulsion this allows to determine the critical coupling strength for spin-density wave formation. We compare the standard approach of introducing a small mass term, explicitly breaking the sublattice symmetry, with a purely geometric mass, i.e. using lattices and boundary conditions such that the Dirac points fall in between the grid points inside the Brillouin zone without explicit sublattice-symmetry breaking. For the first method we extrapolate the corresponding susceptibility peaks towards zero mass and infinite volume in the usual way, while with the geometric mass only infinite volume extrapolation is needed. An added bonus is that it can be used with nearest neighbor repulsion and charge-density wave formation where the corresponding mass term would introduce a sign problem. The geometric mass thus provides a promising method to study the competition between these different types of order and the resulting phase diagram with ab-initio simulations.

Primary authors

Dr Dominik Smith (Justus-Liebig University Giessen) Prof. Lorenz von Smekal (Justus-Liebig University Giessen) Dr Maksim Ulybyshev (Regensbur Univeristy) Dr Pavel Buividovich (Regensburg University)

Presentation Materials