MODULATED MICROWAVE-ABSORPTION SPECTRA FROM JOSEPHSON-JUNCTIONS ON A SCRATCHED NIOBIUM WIRE

Modulated microwave absorption (MMA) spectra from Josephson junction f ormations on a scratched Nb wire have been studied at 9.3 GHz and 4 K. The peak-to-peak separation, delta H of the Josephson lines was found to vary linearly with P-1/2, where P is the applied microwave power, in contrast to a recent interpretation of junction formation in presse d lead pieces by Rubins, Drumheller, and Trybula. The interpretation o f the MMA data on Nb are given in terms of the theory of Vichery, Beun eu, and Lejay for superconducting loops containing weak links.