The characteristics of layers for stratified Luneberg lens

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

2007

Section: Sample Characterizationmentioning

confidence: 99%

Direct-write trilayer technology for Al–Al2O3–Cu superconductor-insulator-normal metal tunnel junction fabrication

Otto

Tarasov

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

2007

“…A comparison of expressions of Eqs. (5) and (6) shows that the differential resistance is proportional to the density of free vortices:…”

Section: Current-voltage Characteristics Of Superconductors Withmentioning

confidence: 99%

“…The smaller part of the vortices is free to move, the smaller is the induced electric field. An important feature of the fractal superconducting structures is that fractality of cluster boundary enhances pinning 6 and, hence, a current-carrying capability of the superconductor. This is demonstrated both in Fig.…”

Section: Current-voltage Characteristics Of Superconductors Withmentioning

confidence: 99%

“…The case of clusters with fractal boundaries provides new possibilities for increasing the critical current value. 5,6 Let us consider the superconductor containing inclusions of a normal phase, which are out of contact with one another. We will suppose that the characteristic sizes of these inclusions far exceed both the superconducting coherence length and the penetration depth.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Vortex Dynamics at the Initial Stage of Resistive Transition in Superconductors with Fractal Cluster Structure

2005

J Low Temp Phys

The effect of fractal normal-phase clusters on vortex dynamics in a percolative superconductor is considered. The superconductor contains percolative superconducting cluster carrying a transport current and clusters of a normal phase, acting as pinning centers. A prototype of such a structure is YBCO film, containing clusters of columnar defects, as well as the BSCCO/Ag sheathed tape, which is of practical interest for wire fabrication. Transition of the superconductor into a resistive state corresponds to the percolation transition from a pinned vortex state to a resistive state when the vortices are free to move. The dependencies of the free vortex density on the fractal dimension of the cluster boundary as well as the resistance on the transport current are obtained. It is revealed that a mixed state of the vortex glass type is realized in the superconducting system involved. The current-voltage characteristics of superconductors containing fractal clusters are obtained and their features are studied.

“…An essential feature of the clusters of defects in superconductor lies in their capability to trap a magnetic flux. 1,2,3,4,5 The cluster structure affects the vortex dynamics in superconductors, especially when clusters have fractal boundary. 6,7,8,9,10,11 A prototype of superconductor containing inclusion of a normal phase is a superconducting wire.…”

Section: Introductionmentioning

confidence: 99%

Vortex Dynamics in Percolative Superconductors Containing Fractal Clusters of a Normal Phase

IEEE Trans. Appl. Supercond.

2005

The effect of fractal clusters on magnetic and transport properties of percolative superconductors is studied. The superconductor contains percolative superconducting cluster carrying a transport current and clusters of a normal phase. It is found that normal phase clusters have essential fractal features. The fractal dimension of the boundary of normal phase clusters is estimated. The currentvoltage (V-I) characteristics of superconductors containing fractal clusters are obtained. It is found that the fractality of the cluster boundary intensifies pinning. This feature permits to enhance the current-carrying capability of the superconductors.