A precursor mechanism triggering the second magnetization peak phenomenon in superconducting materials

AbstractThe correlation in type-II superconductors between the creep rate S and the Second Magnetization Peak (SMP) phenomenon which produces an increase in Jc, as a function of the field (H), has been investigated at different temperatures by starting from the minimum in S(H) and the onset of the SMP phenomenon detected on a FeSe0.5Te0.5 sample. Then the analysis has been extended by considering the entire S(H) curves and comparing our results with those of many other superconducting materials reported in literature. In this way, we find evidence that the flux dynamic mechanisms behind the appearance of the SMP phenomenon in Jc(H) are activated at fields well below those where the critical current starts effectively to increase. Moreover, the found universal relation between the minimum in the S(H) and the SMP phenomenon in Jc(H) shows that both can be attributed to a sequential crossover between a less effective pinning (losing its effectiveness at low fields) to a more effective pinning (still acting at high fields), regardless of the type-II superconductor taken into consideration.

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Behavior of Type II Superconductors in Very High Fields

Electronic Structures in Solids ◽

10.1007/978-1-4899-6537-0_21 ◽

1969 ◽

pp. 283-289

Author(s):

K. Hechler ◽

E. Saur

Keyword(s):

Type Ii ◽

Type Ii Superconductors ◽

High Fields ◽

Very High

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FLUX EXCHANGE IN INHOMOGENEOUS TYPE-II SUPERCONDUCTORS

International Journal of Modern Physics B ◽

10.1142/s0217979214500301 ◽

2014 ◽

Vol 28 (09) ◽

pp. 1450030

Author(s):

RONGCHAO MA

Keyword(s):

Approximate Solutions ◽

Internal Field ◽

Type Ii ◽

System Of Differential Equations ◽

Approximate Methods ◽

Geometrical Size ◽

Type Ii Superconductors ◽

Type Ii Superconductor ◽

Strong Pinning ◽

Application Fields

The vortex hopping motion in a type-II superconductor determines the current-carrying ability and consequently, the application fields of the superconductor. However, it is not clear how the vortices hop between the different pinning regions in the superconductor. Here, we proposed that there should be magnetic flux exchange between two contacting pinning regions. A system of differential equations was constructed to describe the flux exchange phenomenon. The qualitative analysis methods and approximate methods were used. The approximate solutions of the system were obtained. The results show that the flux exchange reduces the internal field in a weak pinning region, but increases the internal field in a strong pinning region. Moreover, the flux exchange is strongly influenced by the superconductor's geometrical size.

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Unveiling the vortex glass phase in the surface and volume of a type-II superconductor

Communications Physics ◽

10.1038/s42005-019-0243-4 ◽

2019 ◽

Vol 2 (1) ◽

Cited By ~ 2

Author(s):

Jazmín Aragón Sánchez ◽

Raúl Cortés Maldonado ◽

Néstor R. Cejas Bolecek ◽

Gonzalo Rumi ◽

Pablo Pedrazzini ◽

...

Keyword(s):

Structural Changes ◽

Condensed Matter ◽

Orientational Order ◽

Vortex Matter ◽

Type Ii ◽

Vortex Glass ◽

Type Ii Superconductors ◽

Type Ii Superconductor ◽

Comprehensive Survey ◽

Bragg Glass

Abstract Order-disorder transitions between glassy phases are common in nature and yet a comprehensive survey on the entailed structural changes is challenging since the constituents are in the micro-scale. Vortex matter in type-II superconductors is a model system where some of these experimental challenges can be tackled. Samples with point disorder present a glassy transition on increasing the density of vortices. A glassy yet quasi-crystalline phase, the Bragg glass, nucleates at low densities. The vortex glass stable at high densities is expected to be disordered, however its detailed structural properties remained experimentally elusive. Here we show that the vortex glass has large crystallites with in-plane positional displacements growing algebraically and short-range orientational order. Furthermore, the vortex glass has a finite and almost constant correlation length along the direction of vortices, in sharp contrast with strong entanglement. These results are important for the understanding of disorder-driven phase transitions in glassy condensed matter.

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Calculations of the equilibrium configurations of flux lines in thin films of type II superconductors

Canadian Journal of Physics ◽

10.1139/p69-187 ◽

1969 ◽

Vol 47 (14) ◽

pp. 1447-1460 ◽

Cited By ~ 20

Author(s):

C. Carter

Keyword(s):

Magnetic Field ◽

Thin Films ◽

Applied Magnetic Field ◽

Type Ii ◽

Gibbs Function ◽

Type Ii Superconductors ◽

Flux Lines ◽

Type Ii Superconductor ◽

Equilibrium Configurations ◽

London Theory

The London theory is used to calculate the equilibrium configurations of flux lines in thin films of a type II superconductor as a function of the applied magnetic field. Three possible geometrical configurations, of increasing complexity, are considered in detail, and the Gibbs function is minimized with respect to the parameters which define the configuration. The range of applied magnetic field for which each configuration is stable is determined, and hence B–H curves are constructed. A transition from one configuration to another causes a discontinuity in the B–H curve at values of H which roughly correspond to those found experimentally by Sutton.

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Interfacial studies in Nb3Sn superconductors

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100087264 ◽

1991 ◽

Vol 49 ◽

pp. 590-591

Author(s):

Ernest L. Hall ◽

Lee E. Rumaner ◽

Mark G. Benz

Keyword(s):

Grain Size ◽

Grain Boundaries ◽

Flux Pinning ◽

Size Control ◽

High Magnetic Fields ◽

Type Ii ◽

Reaction Interface ◽

Liquid Diffusion ◽

Type Ii Superconductor ◽

Grain Size Control

The intermetallic compound Nb3Sn is a type-II superconductor of interest because it has high values of critical current density Jc in high magnetic fields. One method of forming this compound involves diffusion of Sn into Nb foil containing small amounts of Zr and O. In order to maintain high values of Jc, it is important to keep the grain size in the Nb3Sn as small as possible, since the grain boundaries act as flux-pinning sites. It has been known for many years that Zr and O were essential to grain size control in this process. In previous work, we have shown that (a) the Sn is transported to the Nb3Sn/Nb interface by liquid diffusion along grain boundaries; (b) the Zr and O form small ZrO2 particles in the Nb3Sn grains; and (c) many very small Nb3Sn grains nucleate from a single Nb grain at the reaction interface. In this paper we report the results of detailed studies of the Nb3Sn/Nb3Sn, Nb3Sn/Nb, and Nb3Sn/ZrO2 interfaces.

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