title: Phase fluctuations and the pseudogap in YBa(2)Cu(3)O (x).
abstract: The thermodynamics of the superconducting transition is studied as a function of doping using high-resolution expansivity data of YBa(2)Cu(3)O (x) single crystals and Monte Carlo simulations of the anisotropic 3D- XY model. We directly show that T(c) of underdoped YBa(2)Cu(3)O (x) is strongly suppressed from its mean-field value (T(MF)(c)) by phase fluctuations of the superconducting order parameter. For overdoped YBa(2)Cu(3)O (x) fluctuation effects are greatly reduced and T(c) approximately T(MF)(c). We find that T(MF)(c) exhibits a similar doping dependence as the pseudogap energy, naturally suggesting that the pseudogap arises from phase-incoherent Cooper pairing.
authors: Forschungszentrum Karlsruhe, Institut für Festkörperphysik, Karlsruhe, Germany.
authors: C
authors: C
authors: Meingast
authors: V
authors: V
authors: Pasler
authors: P
authors: P
authors: Nagel
authors: A
authors: A
authors: Rykov
authors: S
authors: S
authors: Tajima
authors: P
authors: P
authors: Olsson