arXiv subjects

Sergei A. Sergeenkov

Publications and source records attributed to Sergei A. Sergeenkov.

7 recordsLinked to original sources

arXiv1999

Flicker-noise spectrum in weak-links-containing superconductors

Low-frequency magnetic noise spectrum is calculated within the superconductive glass model. The model predicts the existence of both white noise and flicker-like noise f^{-z} with z strongly dependent on applied magnetic field and temperature. It is shown, in particular, that z increases with field from 0.5 to 1, and that in the critical region (near T_{c}(H)) the 1/sqrt{f} law should prevail in the noise spectrum.

cond-mat.supr-con↗

arXiv1999

Ergodic versus nonergodic behavior in oxygen deficient high-T_c superconductors

The oxygen defects induced phase transition from nonergodic to ergodic state in superconductors with intragrain granularity is considered within the superconductive glass model. The model predictions are found to be in a qualitative agreement with some experimental observations in deoxygenated high-T_c single crystals.

cond-mat.supr-con↗

arXiv1999

Dipole-dipole interaction of Josephson diamagnetic moments

The role of dipole-dipole interaction between Josephson diamagnetic moments is considered within a model system of two clusters (each cluster contains three weakly connected superconducting grains). The sign of the resulting critical current is shown to depend on the orientation between clusters, allowing for both 0 and $π$ type junctions behavior. The possibility of the experimental verification of the model predictions is discussed.

cond-mat.supr-con↗

arXiv1999

Electric Field Induced Converse Piezoeffect in Screw Dislocated YBCO Thin Films

A possible scenario for electric-field induced critical current enhancement in screw dislocated YBCO thin films is proposed based on the converse piezoelectric effect originated from a heavily defected medium of the superconducting films in an applied electric field. The magnitude of the effect is found to depend concurrently on the film thickness and the number of dislocations inside a superconductor.

cond-mat.supr-con↗

arXiv1999

Piezomagnetism and Stress Induced Paramagnetic Meissner Effect in Mechanically Loaded High-T_c Granular Superconductors

Two novel phenomena in a weakly coupled granular superconductor under an applied stress are predicted which are based on recently suggested piezophase effect (a macroscopic quantum analog of the piezoelectric effect) in mechanically loaded grain boundary Josephson junctions. Namely, we consider the existence of stress induced paramagnetic moment in zero applied magnetic field (piezomagnetism) and its influence on a low-field magnetization (leading to a mechanically induced paramagnetic Meissner effect). The conditions under which these two effects can be experimentally measured in high-T_$ granular superconductors are discussed.

cond-mat.supr-con↗

arXiv1998

Magnetic Field Induced Charging Effects in Josephson Junction Arrays

A magnetic field induced electric polarization and the corresponding change of an effective junction capacitance are considered within a 3D model of disordered Josephson junction arrays. At some threshold field (near the Josephson network critical field), the effective junction charge and the related capacitance are shown to reach a maximum and to change a sign, respectively. A possibility to observe the predicted effects in artificially prepared arrays of superconducting grains is discussed.

cond-mat.supr-con↗

arXiv1998

Analog of Magnetoelectric Effect in High-Tc Granular Superconductors

We propose the existence of an electric-field induced nonlinear magnetization in a weakly coupled granular superconductor due to time-parity violation. As the field increases the induced magnetization passes from para- to dia-magnetic behavior. We discuss conditions under which this effect could be experimentally measured in high-temperature superconductors.

cond-mat.supr-con↗