Vortex structures in exponentially shaped Josephson junctions

Vortex structure in exponentially shaped Josephson junctions

We report the numerical calculations of the static vortex structure and critical curves in exponentially shaped long Josephson junctions for in-line and overlap geometries. Each solution of the corresponding boundary value problem is associated with the Sturm-Liouville problem whose minimal eigenvalue allows to make a conclusion about the stability of the vortex. The change in width of the junc...

Zurek-Kibble domain structures: the dynamics of spontaneous vortex formation in annular Josephson tunnel junctions.

Phase transitions create a domain structure with defects, which has been argued by Zurek and Kibble (ZK) to depend in a characteristic way on the quench rate. We present an experiment to measure the ZK scaling exponent sigma. Using long symmetric Josephson tunnel junctions, for which the predicted index is sigma=0.25, we find sigma=0.27+/-0.05. Further, we agree with the ZK prediction for the o...

Experiments on spontaneous vortex formation in Josephson tunnel junctions

Field dependence of the Josephson current and Fiske resonances in specially shaped Josephson junctions

We investigated the magnetic-field dependence of the Josephson current and Fiske resonances in specially shaped Josephson junctions. In order to be able to use junctions for high-resolution X-ray spectroscopy, a very good suppression of the sidelobes of both the Josephson current and the Fiske resonances must be achieved. In a theoretical argument we show that a properly chosen junction shape l...

Kinky Behavior in Josephson Junctions

We analyze nonperturbatively the behavior of a Josephson junction in which two BCS superconductors are coupled through an Anderson impurity. We recover earlier perturbative results which found that a δ = π phase difference is preferred when the impurity is singly occupied and the on-site Coulomb interaction is large. We find a novel intermediate phase in which one of δ = 0 and δ = π is stable w...