title: Superconductivity and the c axis spectral weight of high-T(c) superconductors
abstract: The temperature dependence of the c axis spectral weight (frequency integral of the interplane conductivity) of high transition temperature (high-T(c)) superconductors is shown to be a probe of thermal and quantal fluctuations of the phase of the superconducting order parameter. The behavior of underdoped cuprates is shown to be a natural consequence of superconducting pairing without long-ranged phase coherence. Very underdoped cuprates are found to have strong phase fluctuations, even for temperatures much less than the transition temperature.
authors.affiliation: Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA.
authors.initials: LB
authors.lastname: Ioffe
authors.initials: AJ
authors.lastname: Millis