Magnetic-field modulation of the Josephson effect between polycrystalline CeCu2Si2 and Al

Josephson critical current Ic between a polycrystalline CeCu2Si2 and Al has been measured for the junctions on a CeCu2Si2 surface. A dominant maximum peak at zero magnetic field is observed in the magnetic field H dependence of Ic, suggesting that the Josephson currents flowing from variously-oriented crystallites of CeCu2Si2 are in phase at H = 0. If CeCu2Si2 is in the dx2-y2-wave state, in which the sign of the order parameter changes according to the crystallographic orientation, an s-wave component induced on the surface is considered as a possible origin of the s-wave-like behavior of Ic(H) patterns.