Intrinsic [Formula presented]-Wave Effects in [Formula presented] Grain Boundary Josephson Junctions

We have measured the angular dependence of the Josephson critical current density ([Formula presented]) in [Formula presented]-axis tilt biepitaxial grain boundary [Formula presented] junctions. We observe for the first time intrinsic [Formula presented]-wave pairing symmetry effects manifested as an oscillatory dependence of [Formula presented] on angle. This intrinsic effect is evident even though spontaneous currents, possibly induced by faceting or barrier impurities, are observed in the grain boundaries. © 2002 The American Physical Society.