EFFECT OF GEOMETRY ON FLUXON WIDTH IN A JOSEPHSON-JUNCTION

We investigate the electromagnetic influence of the surrounding idle ( no tunneling) region on static fluxons in window Josephson junctions. We calculated the fluxon width as a function of the size of the idle r egion for three different window (active tunneling area) geometries, n amely elongated truncated rhombus, rectangular and bow-tie and derived approximate expressions for the case of small and large idle regions. The window geometry affects both the fluxon width and the fluxon stab ility. One can define an effective lambda(J) which depends on the junc tion width, the idle region width and the inductance ratio and has imp ortant consequences on the static and dynamic properties of window Jos ephson junctions. We also show the effect of the idle region on the ma ximum tunneling current as a function of the external magnetic held.