Anisotropic Josephson-vortex dynamics in layered organic superconductors

To study the anisotropic Josephson-vortex dynamics in the d-wave superconductors, the interplane resistance has been measured on layered organic superconductors κ ‐ ( ET ) 2 Cu ( NCS ) 2 and β ‐ ( BDA ‐ TTP ) 2 SbF 6 under magnetic fields precisely parallel to the conducting planes. For κ ‐ ( ET ) 2 Cu ( NCS ) 2 , in-plane angular dependence of the Josephson-vortex flow resistance is mainly described by the fourfold symmetry and dip structures appear when the magnetic field is applied parallel to the b- and c-axes. The obtained results have a relation to the d-wave superconducting gap symmetry. However, the absence of in-plane fourfold anisotropy was found for β ‐ ( BDA ‐ TTP ) 2 SbF 6 . The different anisotropic behavior is discussed in terms of the interlayer coupling strength.