title: Magnetic-field induced crossover of superconducting percolation regimes in the layered organic Mott system kappa-(BEDT-TTF)2Cu[N(CN) 2]Cl.
abstract: Fluctuation spectroscopy is used to investigate the organic bandwidth-controlled Mott system kappa-(BEDT-TTF)(2)Cu[N(CN)(2)]Cl. We find evidence for percolative-type superconductivity in the spatially inhomogeneous coexistence region of antiferromagnetic insulating and superconducting states. When the superconducting transition is driven by a magnetic field, percolation seems to be dominated by instable superconducting clusters upon approaching T(c)(B) from above, before a "classical" type of percolation is resumed at low fields, dominated by the fractional change of superconducting clusters. The 1/f noise is resolved into Lorentzian spectra in the crossover region, where the action of an individual fluctuator is enhanced, pointing to a mesoscopic phase separation.
authors.affiliation: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer-Strasse 40, 01187 Dresden, Germany. mueller@cpfs.mpg.de
authors.forename: Jens
authors.initials: J
authors.lastname: Müller
authors.forename: Jens
authors.initials: J
authors.lastname: Brandenburg
authors.forename: John A
authors.initials: JA
authors.lastname: Schlueter