Oscillations of Josephson-Vortex Flow Resistance in Narrow Intrinsic Josephson Junctions

Abstract

Oscillations of Josephson vortex-flow resistance have been studied in narrow (L/spl sim/2-4/spl lambda//sub J/) Bi/sub 2/Sr/sub 2/CaCu/sub 2/O/sub 8+/spl delta// intrinsic Josephson junctions as a function of magnetic field applied parallel to junction edges. Lengths of junctions fabricated are /spl sim/1 /spl mu/m in order to enhance pinning effects of Josephson vortex lattice to the junction edges and thus to enhance formation of rectangular vortex lattice which would lead an in-phase mode of the junctions as a necessary condition for the THz generator application. The observed Josephson vortex flow resistance showed a periodic oscillation with a period (H/sub p/) corresponding to one flux quantum enters per junction, namely, corresponding to the rectangular vortex lattice. Observed strong oscillation was a result of collective behavior of the entry and escape of vortices in a form of rectangular vortex lattice. Peaks in the oscillations were found at the fields H=nH/sub p/, here n shows an integer number. Here, Josephson vortex lattice flow speed shows a local maximum. With this magnetic field, outermost vortex rows geometrically match to the edges of junctions. Contrary to this, a minimum of flow speed, namely pinned state of the vortex lattice, was observed at H=(n+1/2)H/sub p/.