Dresden 2009 – wissenschaftliches Programm
TT 15.12: Vortrag
Dienstag, 24. März 2009, 12:45–13:00, HSZ 301
First order Mott transition at zero temperature in two dimensions: Variational plaquette study — •Matthias Balzer1, Michael Potthoff1, Bumsoo Kyung2, David Senechal2, and A.-M.S. Tremblay2 — 1I. Institut für Theoretische Physik, Universität Hamburg, Germany — 2Département de physique and RQMP, Université de Sherbrooke, Québec, Canada
The nature of the metal-insulator Mott transition at zero temperature has been discussed for a number of years. Whether it occurs through a quantum critical point or through a first order transition is expected to profoundly influence the nature of the finite temperature phase diagram. We study the zero temperature Mott transition in the two-dimensional Hubbard model on the square lattice. Here we use the variational cluster approximation to embed a plaquette of four correlated sites and four or eight uncorrelated bath sites in the lattice. This takes into account the influence of antiferromagnetic short-range correlations. As the method is thermodynamically consistent and focuses on the optimization of a thermodynamical potential, it is ideally suited to distinguish between different phase diagram topologies. By contrast to single-site dynamical mean-field theory, the transition turns out to be first order even at zero temperature.