Fiske steps and hysteresis in $YBa2Cu3O7$ grain boundary Josephson junctions: Structural information of the barrier by means of a nondestructive approach

A deep analysis of the current-voltage $(I-V)$ characteristics of $YBa2Cu3O7$ grain boundary Josephson junctions (GBJJs) allows us to go much farther than the usual calculus of the transport parameters. It is possible to construct a structural image of the barrier by an exhaustive and complementary analysis of both transport and electromagnetic parameters obtained from $I-V$ curves. For such an approach, we have chosen the following three representative bicrystalline geometries: $24°$ [001] asymmetric, $45°$ [100] asymmetric, and $24°$ [001] symmetric $+45°$ [100] asymmetric. The dependence of the product $ICRN$ on the junction normal resistance is of the $ICRN−1$ type pointing to a SNINS model (S denotes superconductor, I denotes insulator, and N denotes normal metal) for all our GBJJs. A satisfactory explanation of the discrepancy of the capacitance of the barrier estimated from Fiske resonance positions and hysteresis in the $I-V$ curves needs of such a model. Moreover an estimation of the length of the normal regions adjacent to the crystallographic barrier can be made. This comparative analysis is presented in order to extract interesting information about the particular transport mechanisms involved in these GBJJs.