24-30 July 2016
Highfield Campus, University of Southampton
Europe/London timezone

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

27 Jul 2016, 10:40
20m
Building 67 Room 1003 (Highfield Campus, University of Southampton)

Building 67 Room 1003

Highfield Campus, University of Southampton

Talk Applications Beyond QCD Applications Beyond QCD

Speaker

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

Description

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 (Regensburg University) Dr Pavel Buividovich (Regensburg University)

Presentation Materials