Narrow long Josephson junctions

Abstract

Long Josephson junctions of width down to less than 0.3 /spl mu/m are fabricated using electron beam lithography. The junctions are made in niobium-aluminum-oxide trilayer technology using cross-linked PMMA for insulation. We measured the fluxon penetration field, the magnetic field period of the critical current modulation, and the Fiske step voltages of the junctions. A strong dependence of these quantities on the junction width is observed. Assuming a general-type relation between the spatial derivative of the phase and the spatial variation of the magnetic field along the plane of the junction, we derive a scaling relation between the measured quantities depending on the junction width. The derived relation is consistent with the experimental data.