Nd1.ssCeo.l5Cu04-, Bicrystal Grain Boundary Josephson Junctions

The study of the detailed influence of the order pa- rameter (OP) symmetry on the properties of high temperature superconducting (HTS) Josephson junctions still is a key issue. Whereas the hole doped HTS such as YBazCu3O7_g (YBCO), BizSrzCaCuzO~+, (BSCCO), or La1.85Sr0.15CuO4-6 (LSCO) are known to have a dominating d-wave component of the OP, there is significant evidence that the electron doped material Nd1.85Ce0.~5Cu04-~ (NO) has a s-wave symmetry of the OP. Therefore, we have studied the electrical transport properties of (OOl) tilt NCCO bicrystal grain boundary Josephson junctions (GBJs) with misorientation angles between 7 and 36.8 and com- pared them to those of the hole doped HTS. For the NCCO-GBJs an exponential decay of the critical current density Je with in- creasing misorientation angle as well as a scaling of the character- istic junction voltage V, = Jf was found very similar to what is observed for the hole doped HTS. This strongly suggests that the OP symmetry is not the key parameter controlling the character- istic properties of HTS-GBJs. In contrast, they are most likely related to the presence of a disorder induced, insulating grain boundary barrier which is similar for both the d- and s-wave HTS.