Berlin 2005 – scientific programme
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TT: Tiefe Temperaturen
TT 35: Correlated Electrons - Quantum Critical Phenomena
TT 35.7: Talk
Wednesday, March 9, 2005, 12:45–13:00, TU H104
Fermi surface symmety breaking on a square lattice — •Hiroyuki Yamase1, Vadim Oganesyan2, and Walter Metzner1 — 1Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, D-70569, Stuttgart, Germany — 2Deparment of Physics, Princeton University, Princeton, NJ 08544, USA
We analyze a mean-field model of electrons with pure forward scattering interactions on a square lattice, which exhibits spontaneous Fermi surface symmetry breaking with a d-wave order parameter. As a function of chemical potential, the phase transition is typically first order at low temperature (T) and second order at high T. It is, however, found that Fermi surface fluctuations near the first order transition can be strong. When a repulsive constant contribution to the forward scattering interaction is added, the first order transition is suppressed and tricritical points at the ends of the second order transition line are shifted to lower T. Although the shift is usually not strong enough to lead to a quantum critical point (QCP), we find a limited parameter region where a QCP can be realized. In the weak coupling limit, the transition of the Fermi surface symmetry breaking is characterized by universal functions of suitably rescaled parameters.