Pseudogaps and phase-fluctuations

Systems with itinerant fermions close to a zero temperature quantum phase transition like the high temperature superconductors exhibits unusual non-Fermi liquid properties. The interaction of the long-range and low-energy fluctuations of the incipient order with the fermions modifies the dynamical properties of the fermions strongly by inducing effective long-range interactions. Close to the transition, the interaction of the order parameter fluctuations becomes important. In this paper we discuss the physics of phase-fluctuations in a two-dimensional superconductor and their effect on the electronic spectrum.