Results 1 - 10 of 39
Results 1 - 10 of 39. Search took: 0.017 seconds
|Sort by: date | relevance|
[en] A bare three-dimensional model, in which grains are reduced to points, cannot fully account for the magnetic properties of granular superconductors. A dressed version of these network models is proposed to discuss the quantitative link between the low-field magnetic response of high-Tc superconducting granular samples and the characteristic properties of Josephson junction network models. By means of dressed models, the temperature dependence of the d.c. field-cooled susceptibility of a simple three-dimensional granular system, consisting of eight grains in a cubic arrangement, is studied
[en] Highlights: • We generalize, in the realm of the Ginzburg–Landau theory, the de Gennes matching-matrix method for the interface order parameters to describe the superconducting properties of multi-band mesoscopic Josephson junctions. • The results are in agreement with a microscopic treatment of nanobridge junctions. • Thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions. - Abstract: A Ginzburg–Landau theory for multi-band mesoscopic Josephson junctions has been developed. The theory, obtained by generalizing the de Gennes matching-matrix method for the interface order parameters, allows the study of the phase dynamics of various types of mesoscopic Josephson junctions. As a relevant application, we studied mesoscopic double-band junctions also in the presence of a superconducting nanobridge interstitial layer. The results are in agreement with a microscopic treatment of the same system. Furthermore, thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions.
[en] Highlights: • I–V characteristics of triple-barrier Josephson junctions (TBJJs) are studied. • The I–V characteristics are identical to those of an ordinary single-barrier Josephson junction. • In the presence of r. f. radiation integer and fractional Shapiro steps appear. - Abstract: Current–voltage characteristics of triple-barrier Josephson junctions are analytically and numerically studied. In the presence of a constant current bias and for homogeneous Josephson coupling of all layers, these systems behave exactly as ordinary Josephson junctions, despite their non-canonical current-phase relation. Deviation from this behaviour is found for inhomogeneous Josephson coupling between different layers in the device. Appearance of integer and fractional Shapiro steps are predicted in the presence of r. f. frequency radiation. In particular, the amplitudes of these steps are calculated in the homogeneous case as clear footprints of the non-canonical current-phase relation in these systems
[en] The influence of coupling inhomogeneities on the static magnetic response of a three-dimensional 8 x 8 x 8 network of Josephson junctions is studied numerically. The inhomogeneities we consider are of two types. The first consists of an extended low-coupling-energy region in the network, the second is realized by taking the in-plane superconducting coupling energy ten times higher that the coupling energy between planes. The present analysis is carried out for conventional 0-junctions
[en] The periodic effective potential of a superconducting quantum interference device containing an underdamped Josephson junction in the first branch and a double-barrier junction in the second is studied. An effective non-sinusoidal expression for the current-phase relation with an additional half harmonic term is used for the double-barrier junction. The system allows voltage rectification under opportunely chosen parameter values.
[en] Coupling inhomogeneities in the Josephson junctions of planar 0-SQUIDs and π-SQUIDs and of three-dimensional SQUIDs are considered. Starting from the properties of planar SQUIDs, it is shown that slight non-homogeneous couplings of the twelve junctions in three-dimensional superconducting interferometers do not affect the periodicity properties of voltage versus applied flux curves. The results are obtained by applying a rigorous and general analytic approach to planar and three-dimensional superconducting devices.
[en] A one-dimensional array of N cells of 0- and π-junctions in parallel is considered. By assuming that junction parameters and effective loop areas alternate as one moves along the longitudinal direction of the array, going from 0- to π-junctions, an effective single-junction model is derived. By this model, interference patterns of the critical current as a function of the applied magnetic flux can be analytically found.
[en] It is shown that, by applying elementary concepts in electromagnetism and electrochemistry to a system consisting of salt water flowing in a thin rectangular pipe at an average velocity vA under the influence of a transverse magnetic field B0, an electromotive force generator can be conceived. In fact, the Lorentz force acting on the sodium and chlorine ions in a water solution gives rise to a so-called Faraday voltage across the two metal electrodes, positioned at the sides of the pipe. The effect is carried along the following chemical reactions at the electrodes: at the cathode, water is reduced (instead of sodium ions) and hydrogen gas is generated; at the anode, chlorine gas is produced. In college physics teaching, this interdisciplinary subject can be adopted to stress analogies and differences between the Hall voltage in conductors and the Faraday voltage in electrolyte solutions
[en] The current-phase relations of a double-barrier Josephson junction with a thin intermediate electrode show deviations from the usual sinusoidal dependence of a single Josephson junction. The skewness of these curves can be analytically found for small values of the coupling between the two outer electrodes of the double-barrier Josephson junction. -- Highlights: → Important parameters for SISIS junction properties are defined. → Current-phase relations of these junctions are shown in terms of these parameters. → Skewness in the current-phase relations of these junctions is analytically calculated.
[en] Repeated elastic collisions of point particles on a finite frictionless linear track with perfectly reflecting endpoints are considered. The problem is analysed by means of an elementary linear algebra approach. It is found that, starting with a state consisting of a projectile particle in motion at constant velocity and a target particle at rest in a fixed known position, the points at which collisions occur on track, when plotted versus progressive numerals, corresponding to the collisions themselves, show periodic patterns for a rather large choice of values of the initial position x(0) and on the mass ratio r. For certain values of these parameters, however, only regular behaviour over a large number of collisions is detected