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Investigates the effect of high-energy ion irradiation and electron irradiation on textured tapes. Comparison of the efficiency of ion irradiation and electron irradiation in increasing intragrain and irreversibility fields of the tapes; Explanation for the low transport critical current density of polycrystalline oxide superconductors; Preparation of the samples.

Presents information on a study which determined the flux pinning energies and their distributions at 77 K in silver-headed and c-axis-oriented Bi2223 superconducting tape by 90° rotating sample magnetic measurements. Distribution of flux pinning energies in the tape; Methodology; Results and discussion; Conclusions.

Examines the role of the voltage criterion in the interpretation of flux pinning in epitaxial films of yttrium compound. Factors influence the future application of high-temperature superconductors; Preparation of the thin film sample; Experimental results and discussion.

The vortex motion in Cu0.03TaS2 has been investigated by resistivity results with a special electrode arrangements. The vortex behaviors for H c are completely different from that for H ab. The analysis indicates that when H ab, the sharp ρ - T transition is the superconductive-normal transition while for H c, the broadened ρ - T transition is caused by the suppression of the superconducting weak link between the S-Ta-S layers. The existence of the vortex pancake in Cu0.03TaS2 is contradictory to the Clem's model, further demonstrating that the models for high temperature cuprates superconductors are not applicable to the layered transition metal dichalcogenides. [ABSTRACT FROM AUTHOR]

We developed a self-consistent method for the calculation of spatial current distributions in high- T grain-boundary junctions. It is found that crystallographic anisotropy of high- T superconducting electrodes results in the effects, which previously were not taken into account for interpretations of experimental data. Among them is a significant redistribution of electrical currents in superconducting electrodes in the vicinity of a grain boundary. In particular in the case of [100]-tilt bicrystal junctions, this current redistribution results in a substantial focusing to the top or bottom part of a thickness of the grain boundary, depending on 'roof'- or 'valley'-type of the grain boundary. This redistribution is accompanied by generation of vortex currents around the grain boundary, which leads to self-biasing of grain-boundary junctions by magnetic field nucleated by these vortex currents. It is shown that twinning or variation of geometrical shape of the high- T electrode may also result in intensive redistribution of electrical currents and nucleation of local magnetic fields inside a high- T superconducting electrodes. [ABSTRACT FROM AUTHOR]

Magnetic measurements are reported on YBCO thin films (d<500 nm) in the perpendicular geometry, H||c. By analyzing the sweep rate dependence of the magnetization for temperatures 35≤ T≤77 K and H≤10 kOe, we find that the moment has a power law dependence on the sweep rate. This dependence is indicative of power law E(J) characteristics for these thin films and from this a logarithmic current dependence of the activation potential U(J) is inferred. We find that our magnetic relaxation measurements are also consistent with the logarithmic U(J) dependence obtained from the sweep rate measurements. Activation barriers for flux creep are determined for various temperatures and their field dependence is discussed. [ABSTRACT FROM AUTHOR]

Discusses different measurement configurations using four probe methods and lock-in detection on alternating current (AC) loss of superconducting cable conductors. Need for voltage to be picked up at the end of connecting joints; Measurements indicating size of the loop constituted by the voltage leads has no influence on measurements.

It is argued that vortices in layered superconductors will be trapped by tilted columnar defects even when the external magnetic field is oriented along the c axis. For such tilted, trapped vortices the interaction at long distances becomes attractive in some directions. This must result in the formation of vortex chains with an intervortex distance of the order of the London penetration depth. [ABSTRACT FROM AUTHOR]

Examines stacking faults, ionic vacancies, columnar defects, grain boundaries, and other crystal defects that play crucial roles in determining the superconducting properties of high-Tc layered cuprates and can be exploited to optimize superconductivity. Oxygen stoichiometry and Tc; Stacking defects and multilayer deposition; Columnar defects and flux pinning; Grain boundaries and critical currents; More.

The effect of 200 MeV Ag ion irradiation on the temperature and field dependence of critical current density (J[sub C]) of high quality MgB[sub 2] thin films is studied. Substantial increase in J[sub C] is observed over a certain field range for the film irradiated at a dose of 10[sup 12] ions/cm[sup 2]. Our analysis suggests that columnar defects are not formed under irradiation conditions used in these studies, which correspond to an electronic energy loss of about 16 keV/nm. Defects clusters are likely to be responsible for the observed improvement in J[sub C].© 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Describes the increase in the pinning energy and critical current density in single superconductor crystal. Generation of defect structure other than point defects acting as pinning center; Effect of higher pinning energy on critical current density.

Examines the efficacy of heavy ion damage J[sub C] of superconductors Bi[sub 2]Sr[sub 2]Ca[sub 1]Cu[sub 2]O[sub 8]. Investigation of critical current density J[sub c] and irreversibility line using superconducting quantum interference device; Influence of linear defects on the production of the pinning of vortices; Effect of heavy ion irradiation on critical current density.