Amplitude sensitive experiment of pairing symmetry in d0-d0 submicron Y-Ba-Cu-O bicrystal grain boundary junctions

We have fabricated and analyzed submicron YBa2Cu3O7-x grain boundary Josephson junctions grown on [100] tilt SrTiO3 bicrystal substrates. We present an experiment sensitive to the amplitude of the order parameter. To this aim, we have measured electrical properties of [100] tilt bicrystal YBa2Cu3O7-x grain boundary junctions with nominal widths of 700 nm and 300 nm. Junctions are fabricated so that positive lobes of the d-wave electrodes face one another (d0-d0 junction). We demonstrate that, in such devices, the temperature dependences of the critical current may be accounted for by very high-transparency junction barriers, in which the influence of nodes in the pair potential is an essential element. We based our analysis on a recent theoretical model that, starting from the Bogoliubov-de Gennes equations, takes into account the presence of Andreev bound states in layered superconductors, with Cu-O planes tilted with respect the substrate plane, as is the case of [100] tilt grain boundary junctions.