Phase-Sensitive Test of UPt3Using Josephson Interferometry

Josephson critical current I c between a single crystal UPt 3 and Al has been measured for a corner junction on the UPt 3 faces perpendicular to the a [11 2 0] and b [10 1 0] axes. The magnetic field dependence of I c has shown a global maximum at zero magnetic field like the junctions on a single face. We have not observed a behavior indicating the phase shift of the order parameter between the a - and b -axis directions thus far.