SUPERCONDUCTIVITY IN BAD METALS

We introduce a model of the superconducting transition in a bad metal, and show that quantum and classical phase fluctuations prevent long-range order unless the resistivity (T) falls below a critical value. Application of these ideas to high temperature superconductors accounts for the variation of (Tc) in radiation-damaged films; gives an upper bound on Tcns, where ns is the zero-temperature superfluid density; and shows that, with screening, phase fluctuations give a linear temperature dependence of ns at low temperatures. © 1995 The American Physical Society.