First Observation for a Cuprate Superconductor of Fluctuation-Induced Diamagnetism Well Inside the Finite-Magnetic-Field Regime

Abstract

For the first time for a cuprate superconductor, measurements performed above T(c) in high quality grain aligned La1.9Sr0.1CuO4 samples have allowed the observation of the thermal fluctuation induced diamagnetism well inside the finite-magnetic-field fluctuation regime. These results may be explained in terms of the Gaussian Ginzburg-Landau approach for layered superconductors, but only if the finite field contributions are estimated by taking off the short-wavelength fluctuations.