Inhomogeneous interlayer Josephson coupling in kappa-(BEDT-TTF)(2)Cu(NCS)(2)

In a layered superconductor, the interlayer coupling strength determines th e spatial variation of the magnetic fields parallel to the layers. Scanning SQUID microscope images of an edge of a single crystal of the layered orga nic superconductor kappa-(BEDT-TTF)(2)Cu(NCS)(2) show regions of inhomogene ous coupling as well as trapped interlayer Josephson vortices. Quantitative modelling of individual isolated vortices indicates an interlayer penetrat ion depth lambda(perpendicular to) similar to 60 mu m. Previous bulk measur ements that indicated a weaker interlayer coupling may have been dominated by inhomogeneities.