Observation of coherent Josephson response in the non-linear ab-plane microwave impedance of $YB{a}_{2}C{u}_3{O}_{6.95}$ single crystals

Abstract

We report novel non-linear phenomena in the $ab$-plane microwave impedance of $YBaC{u}_2{O}_{7-\hat{I}´}$ single crystals. The $R_s$ vs. $H_{rf}$ data are well described by the non-linear RSJ model : $\dot{\ddot{I}}•+\sin \ddot{I}•=i_{rf}\cos \ddot{I}‰t$. The entire crystal behaves like a single Josephson junction. The extraordinary coherence of the data suggests an intrinsic mechanism.

2 pages,1 figure, Submitted to Proc. of M^2SHTSC-V (Beijing), also available at http://sagar.physics.neu.edu/preprints