Temperature dependence of the Josephson plasma resonance between vortex phases in the organic superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2)

摘要

Using a microwave cavity perturbation technique, we probe different regimes of vortex interactions within the mixed superconducting state of the title compound. A Josephson plasma resonance (JPR) is observed which is sensitive to correlations between pancake vortices in adjacent layers. Previous investigations have conclusively identified a transition between liquid-like and pinned solid or glassy vortex phases. Here, we study this behavior via field-cooled experiments, obtaining further evidence for the transition. These experiments also allow us to probe the JPR over a wider range in temperature and magnetic 2) field within the liquid phase than was previously reported. Theoretical models predict a squared plasma frequency (cop which follows a power law dependence on magnetic field (B) within both phases, i.e. omega(p)(2) proportional to B-mu. Our data agree well with this model, allowing a determination of the zero-field interlayer critical current density (J(0)) and the parameter mu. Indeed, this parameter (mu) is seen to follow a dependence on frequency which is indicative of a continuous transition between the two vortex phases. (C) 2004 Elsevier Ltd. All rights reserved.