This title appears in the Scientific Report :
1999
Please use the identifier:
http://hdl.handle.net/2128/20458 in citations.
Multi-layer Josephson tunnel junctions
Multi-layer Josephson tunnel junctions
The most important active element in superconducting circuits are Josephson junctions. Their high frequency properties motivated many different projects to implement Josephson junctions in circuits for active and passive devices. The limiting points for applications in the low temperature supercondu...
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Personal Name(s): | Thyssen, N. |
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Contributing Institute: |
Institut für Schicht- und Ionentechnik; ISI |
Imprint: |
Jülich
Forschungszentrum, Zentralbibliothek
1999
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Dissertation Note: |
Erlangen-Nürnberg, Univ., Diss., 1999 |
Document Type: |
Book Dissertation / PhD Thesis |
Research Program: |
ohne FE |
Series Title: |
Berichte des Forschungszentrums Jülich
3656 |
Subject (ZB): | |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
The most important active element in superconducting circuits are Josephson junctions. Their high frequency properties motivated many different projects to implement Josephson junctions in circuits for active and passive devices. The limiting points for applications in the low temperature superconducting field are broad line width and small power of a single Josephson junctions. The present work presents experimental and theoretical investigations on vertical stacked Josephson junctions in linear or annular geometry. Presenting results of up to 28 stacked elements is the state of the art of preparing stacked Low-T, Josephson Tunnel Junctions. Stacks of up to 10 junctions show a parameter spread of less than 5% due to the developed preparation procedures. Magnetic flux quanta in Josephson junctions, called fluxons, in many cases behave as solitons. Recent experiments and modeling offluxon dynamics in annular Josephson junctions show the influence of an external magnetic field on a single moving fluxon. The resulting dynamics are strongly analogous to the motion of a particle in a washboard potential. Experiment, theoretical model and numerical simulations are in good agreement. Experiments on fluxons in two-fold stacks show the dynamic and static properties of this configuration. The critical current dependence on the external magnetic field displays different possible values, due to the voltage states of the junctions. First experimental hints on Cherenkov radiation by resonant structures in the current-voltage (I-V) characteristic is found with stacks prepared during this work. The flux-flow dynamics in N-Iayered Nb/AI-AIOJNb Josephson tunnel junctions is investigated experimentally and by numerical simulations. Collective flow of Josephson vortices is displayed in the magnetic field dependent I-V characteristics as cavity-like resonances. Numerical calculations with a finite difference method, using the coupled sineGordon equation explain these structures, accounted by the calculated characteristic frequencies. Voltage-locked flux-flow motion in the inner junctions is found. The difference to the outer junctions is explained by the film thickness which leads to higher fluxon numbers in those junctions. Numerical data and experiments show very good overall agreement. First experimental results on radiation emission of stacked junctions are shown. First results about sub-micrometer junction preparation and high quality junctions in X-band coupling circuits show the broad field of application for the developed preparation machine and procedures. |