Magnetic field penetration in a long Josephson junction imbedded in a widestripline

The dependence of the first critical field of long linear and annular Josep hson junctions on the width of the surrounding stripline, the so called idl e region, is investigated experimentally. The stripline modifies the effect ive Josephson length lambda (eff) in the junction. The experimental data ar e compared with the theory by Caputo [J. Appl. Phys. 85, 7291 (1999)] and g ood agreement is found. The dependence of the first critical field on the w idth of the surrounding stripline can be well explained using the same lamb da (eff) for both annular and linear junctions. (C) 2001 American Institute of Physics.