Kosterlitz–Thouless type of superconducting phase fluctuations investigated by frequency-dependent microwave conductivity of underdoped La 2− xSr xCuO 4 thin films

Abstract

We report the ac fluctuating microwave conductivity as a function of swept-frequency ( ω/2π = 0.1–12 GHz) for underdoped La 2− x Sr x CuO 4 thin films in the zero and the small finite magnetic fields. Our results strongly suggested that the phase fluctuation in the superconductivity order parameter was diminished at a much lower temperature than a closing temperature of the pseudogap. Thus, most of anomalies in the pseudogap region should be explained by other origins than the superconducting phase fluctuations.