Effect of Transverse Magnetic Fields on dc Josephson Current

We have observed diffraction patterns in critical dc Josephson tunnel current versus magnetic field applied perpendicular to the junction plane. The patterns can be explained by assuming that the perpendicular field penetrates the edge of each film and channels through the junction parallel to the films. An "edge penetration depth," ${\lambda }_{\perp }$, gives a quantitative description of the patterns and their dependence on the angle of field direction. We have found ${\lambda }_{\perp }\mathrm{}\left(T\right)\mathrm{}\propto {(1-\frac{T}{T_c})}^{-\frac{1}{2}}$.