University
of Toronto
Physics Department
Quantum Optics and Condensed Matter
MONDAY SEMINAR
University
of Toronto
| Speaker : | PROFESSOR PHILIP PHILLIPS
Department of Physics University of Illinois at Urbana-Champaign |
| Topic : | PAIRING AND FLUX PHASES IN THE 2D HUBBARD MODEL |
| Time : | Monday, May 7, 2001 at 12:10 p.m. |
| Place : | Room MP408, Burton Tower 60 St. George Street / 255 Huron Street |
Abstract
The 2D Hubbard model is the simplest interacting model that is thought to capture much of the exotic physics of strongly-correlated systems such as the cuprates. In the relevant parameter space for such materials, the Coulomb repulsion is the largest energy scale. Consequently, perturbative expansions are unjustified. I will report on a non-perturbative approach to the Hubbard model which aims to address such questions as 1) what are the basic charge carriers at finite doping, 2) does the Hubbard gap close at half-filling, and 3) under what conditions do exotic flux phases exist? In strong coupling, composite particles obtain which exhibit d-wave pairing tendencies in the absence of quantum fluctuations. I will also show that the half-filled Hubbard models are always in the non-perturbative regime and that nearest-neighbour attractions must be present to stabilise the staggered flux phase.
Local Host: Michael Walker
(416-978-3821) 
See http://www.physics.utoronto.ca/~qocmp