The remanent magnetization of Bi-Ca-Sr-Cu-O ceramic rings in weak magnetic fields

High temperature superconductivity : new materials and properties : joint symposium of the SB RAS and the CNEAS TU / edited by Kyosuke Terayam

Magnetic flux dynamics in critical state of one-dimensional discrete superconductor

We give a theoretical description of avalanche-like dynamics of magnetic flux in the critical state of "hard" type-II superconductors using a model of a one-dimensional multijunction SQUID that well reproduces the main magnetic properties of these objects. We show that the system under consideration demonstrates the self-organized criticality. The avalanches of vortices manifest themselves as jumps of the total magnetic flux in the sample. The sizes of these jumps have a power-law distribution. Our results are in qualitative agreement with experiments.Comment: 7 pages, 5 figure

Novel magnetoinductance effects in Josephson Junction Arrays: A single-plaquette approximation

Using a single-plaquette approximation, novel magnetoinductance effects in Josephson junction arrays (JJAs) are predicted, including the appearance of steps in the temperature behavior of magnetic susceptibility. The number of steps (as well as their size) is controlled by the kinetic inductance of the plaquette whose field dependence is governed by the Abrikosov vortices penetrating superconducting regions of the array. The experimental conditions under which the predicted effects should manifest themselves in artificially prepared JJAs are discussed.Comment: Accepted for publication in PL

Manifestation of geometric quantization effects in temperature behavior of AC magnetic response of Josephson Junction Arrays

By improving resolution of home-made mutual-inductance measurements technique, a pronounced step-like structure (with the number of steps n=4 for all AC fields) has been observed in the temperature dependence of AC susceptibility in artificially prepared two-dimensional Josephson Junction Arrays (2D-JJA) of unshunted Nb-AlO_x-Nb junctions with \beta_L(4.2K)=30. Using a single-plaquette approximation of the overdamped 2D-JJA model, we were able to successfully fit our data assuming that steps are related to the geometric properties of the plaquette. The number of steps n corresponds to the number of flux quanta that can be screened by the maximum critical current of the junctions. The steps are predicted to manifest themselves in arrays with the inductance related parameter \beta_L(T) matching a "quantization" condition \beta_L(0)=2\pi (n+1).Comment: 4 pages (jetpl style), 3 figure

On Field Induced Diaelastic Effect in a Small Josephson Contact

An analog of the diaelastic effect is predicted to occur in a small Josephson contact with Josephson vortices manifesting itself as magnetic field induced softening of the contact shear modulus C(T,H). In addition to Fraunhofer type field oscillations, C(T,H) is found to exhibit pronounced flux driven temperature oscillations near T_C