112 research outputs found
Critical current density and trapped field in HTS with asymmetric magnetization loops
Applications of the extended critical state model are considered. The trapped
magnetic field, the penetration field and the field dependence of the critical
current density are analysed. The critical current density and the trapped
field in superconducting grains depend on the grain size. Asymmetry of the
hysteresis curves relative to the M = 0 axis is related to the scale of the
current circulation.Comment: 5 pages, 4 figures, presented in the 9th International Workshop on
Processing and Applications of Superconducting (RE)BCO Large Grain Materials
(PASREG 2015
Magnetic flux trapping in porous superconductors
The magnetization of superconducting samples is influenced by their porosity.
In addition to structural modifications and improved cooling, the presence of
pores also plays a role in trapping magnetic flux. Pores have an impact on the
irreversibility field, the full penetration field, and the remnant
magnetization. Generally, as porosity increases, these parameters tend to
decrease. However, in the case of mesoscopic samples or samples with low
critical current densities, increased porosity can actually enhance the
trapping of magnetic flux.Comment: 9 pages, 3 figure
Computation of current-voltage characteristics of weak links
Simplified model for current-voltage characteristics of weak links is
suggested. It is based on approach which considers Andreev reflections as
responsible for the dissipative current through the metallic Josephson
junction. The model allows to calculate current-voltage characteristics of weak
links (superconductor - normal metal - superconductor junctions, microbridges,
superconducting nanowires) for different thicknesses of the normal layer at
different temperatures. The current-voltage characteristics of tin microbridges
at different temperatures were computed.Comment: 11 pages, 5 figure
Asymmetry of magnetization curves of textured BSCCO
The dependence of magnetization on magnetic field M(H) was measured for
textured BSCCO samples for H || c, H || ab at different temperatures. Inclusion
of the pinning parameter in the Valkov-Khrustalev model [V.V. Valkov, B.P.
Khrustalev, JETP 80 (1995) 680] allowed to describe successfully the asymmetric
M(H) dependencies. The temperature and magnetic field dependencies of critical
current and pinning parameter for H || c and H || ab were estimated.Comment: 4 pages, 1 figure, will be published in Physica
Description of hysteretic current-voltage characteristics of SNS junctions
Simplified model for current-voltage characteristics of weak links is
suggested. It is based on an approach considering the multiple Andreev
reflection in metallic Josephson junction. The model allows to calculate
current-voltage characteristics of the superconductor - normal metal -
superconductor junctions with different thicknesses of normal layer at
different temperatures. A hysteretic peculiarity of dependence is
described as result of the negative differential resistance. The
current-voltage characteristic of high- composite YBCO +BaPbO were
computed.Comment: 9 pages, 5 figures, submited to Supercond. Sci. Technol, replased
Fig.5 for more correct comparison with experimen
Current - voltage characteristics of break junctions of high- superconductors
The current-voltage (-) characteristics of break junctions of
polycrystalline LaSrCuO,
YLuBaCuO,
BiPbSrCaCuO and composite
YBaCuO + Ag are investigated. The experimental -
curves exhibit the specific peculiarities of
superconductor/normal-metal/superconductor junctions. The relation between an
- characteristic of network of weak links and - dependencies of
typical weak links is suggested to describe the experimental data. The -
curves of typical weak links are calculated by the K\"{u}mmel - Gunsenheimer -
Nicolsky model considering the multiple Andreev reflections.Comment: 9 pages, 5 figures, 2 Table
Secondary peak on asymmetric magnetization loop of type-II superconductors
Asymmetric magnetization loops with a second peak effect were parameterized
by the extended critical state model. The magnetic field distribution in a
sample is considered. Expression is suggested for a peak of the critical
current density and corresponding depression on field dependence of the depth
of surface layer with equilibrium magnetization. These functions determine the
width and the asymmetry of a magnetization loop. Asymmetry of the secondary
peak height on magnetization branches for increasing and decreasing field is
reproduced on the computed magnetization curves.Comment: 6 pages, 2 figures, Equation 6 is modified to be f=0 at B=
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