title: Correlated conductance fluctuations close to the Berezinskii-Kosterlitz-Thouless transition in ultrathin NbN films.
abstract: We probe the presence of long-range correlations in phase fluctuations by analyzing the higher-order spectrum of resistance fluctuations in ultrathin NbN superconducting films. The non-Gaussian component of resistance fluctuations is found to be sensitive to film thickness close to the transition, which allows us to distinguish between mean field and Berezinskii-Kosterlitz-Thouless (BKT) type superconducting transitions. The extent of non-Gaussianity was found to be bounded by the BKT and mean field transition temperatures and depends strongly on the roughness and structural inhomogeneity of the superconducting films. Our experiment outlines a novel fluctuation-based kinetic probe in detecting the nature of superconductivity in disordered low-dimensional materials.
authors.affiliation: Department of Physics, Indian Institute of Science, Bangalore 560 012, India.
authors.forename: R
authors.initials: R
authors.lastname: Koushik
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Kumar
authors.forename: Kazi Rafsanjani
authors.initials: KR
authors.lastname: Amin
authors.forename: Mintu
authors.initials: M
authors.lastname: Mondal
authors.forename: John
authors.initials: J
authors.lastname: Jesudasan
authors.forename: Aveek
authors.initials: A
authors.lastname: Bid
authors.forename: Pratap
authors.initials: P
authors.lastname: Raychaudhuri
authors.forename: Arindam
authors.initials: A
authors.lastname: Ghosh