STATIC AND DYNAMIC PROPERTIES OF VORTICES IN A SMALL JOSEPHSON-JUNCTION ARRAY

An array consisting of 12 junctions arranged in a triangular lattice h as recently been observed to exhibit quantum interference of vortices. That vortices should exist in such small arrays and exhibit classical behavior qualitatively similar to those found in larger arrays has be en an important assumption for the interpretation of experimental resu lts. We therefore investigate, using static and dynamic simulations, t he classical properties of vortices in a small Josephson-junction arra y. By employing a relaxation technique, we find that the energy barrie r, U(b), preventing a single vortex from moving from the center of one array-lattice site to the next is dependent on the applied frustratio n f, where f is the number of flux quanta per unit cell. Solving the s et of coupled-second order differential equations derived from the RCS J model, we observe for f greater-than-or-equal-to 0.08 a vortex-flow region in the array's I-V characteristic.