Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 5: Correlated Electrons - (General) Theory

TT 5.9: Vortrag

Montag, 26. März 2007, 16:45–17:00, H18

Competition of Pomeranchuk instability and superconductivity — •hiroyuki yamase and walter metzner — Max-Planck-Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany

We analyze a mean-field model of electrons on a square lattice with two types of interaction: forward scattering favoring d-wave Fermi surface symmetry breaking (Pomeranchuk instability) and a BCS interaction driving d-wave superconductivity. Tuning the interaction parameters a rich variety of phase diagrams is obtained. If the BCS interaction is not too strong, Fermi surface symmetry breaking is obtained around van Hove filling, and coexists with superconductivity at low temperatures. In the presence of a paring gap it is easier to realize Fermi surface symmetry breaking via a continuous phase transition at low temperatures than without. For a relatively strong BCS interaction, Fermi surface symmetry breaking can be limited to intermediate temperatures, or can be suppressed completely by pairing.