Title :
Coherent flux-flow in vertically stacked long Josephson tunnel junctions
Author :
Ustinov, A.V. ; Kohlstedt, H. ; Heiden, C.
Author_Institution :
Inst. fur Schicht- und Ionentech., Forschungszentrum Julich GmbH, Germany
fDate :
6/1/1995 12:00:00 AM
Abstract :
Vertical stacks of two Nb/Al-AlO/sub x//Nb long Josephson junctions with nearly identical parameters have been studied experimentally. The magnetic coupling between the junctions was provided by their common electrode of thickness d/spl sime//spl lambda//sub L/. The I-V characteristics displayed flux-flow resonances of the two junctions. Two different mutually phase-locked regimes were found: the lower velocity anti-phase mode, and the high velocity in-phase mode. These modes, while staying locked, could be tuned by the magnetic field in a broad voltage range which corresponds to the Josephson frequencies of 150-600 GHz for the lower mode and 280-400 GHz for the upper mode. Our observations suggest applications of the stacked long Josephson junctions as local oscillators for millimeter and sub-millimeter wave circuits.<>
Keywords :
Josephson effect; aluminium; flux flow; millimetre wave oscillators; niobium; phase locked oscillators; submillimetre wave oscillators; superconducting device testing; superconducting junction devices; 150 to 600 GHz; 280 to 400 GHz; Fiske steps; I-V characteristics; Josephson frequencies; Nb-Al-AlO-Nb; Nb/Al-AlO/sub x//Nb long Josephson junctions; coherent flux-flow; common electrode; flux-flow resonances; high velocity in-phase mode; local oscillators; low velocity antiphase mode; magnetic coupling; magnetic field tuning; millimeter wave circuits; mutually phase-locked regimes; submillimeter wave circuits; vertically stacked long Josephson tunnel junctions; Couplings; Electrodes; Frequency; Josephson junctions; Laser mode locking; Local oscillators; Magnetic fields; Magnetic resonance; Niobium; Voltage;
Journal_Title :
Applied Superconductivity, IEEE Transactions on
