The Influence of Dislocations on Superconductivity

Gurp, G. J. van; Ooijen, D.J. van

doi:10.1051/jphyscol:1966307

Cited by 8 publications

(6 citation statements)

References 13 publications

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“…Indeed, many classical publications on pinning deal with high κ material (large λ, small ξ), since it is the case for all the superconductors used for magnet developments, where pinning plays a large role. In the case of niobium, with κ ∼ 1 some of the numerical approximations do not hold anymore and relative pinning forces need to be reconsidered [27].…”

Section: A General Observationsmentioning

confidence: 99%

Influence of crystalline structure on rf dissipation in superconducting niobium

Antoine

2019

Phys. Rev. Accel. Beams

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Bulk niobium is the most common material used in the fabrication of rf superconducting cavities for accelerators. Predicting and reducing the rf surface dissipation in these cavity structures is mandatory, since it has a tremendous cost impact on the large accelerator projects. In this paper the author hopes to demonstrate that sources of dissipation usually attributed to external causes (mainly flux trapping during cooldown and hydrides precipitates) are related to the same type of crystalline defects that affect the local superconducting properties and can be at the source of early vortex penetration at the surface. We also want to show how these types of defects can explain some of the discrepancies observed from other laboratories in niobium cavity doping experiments. Understanding the origin and the role of these defects could provide direction for improving material specifications as well as improving fabrication control from sheet material to completed cavity. In particular, we will demonstrate that dislocation entanglements, due to the fabrication damage layer, have the strongest impact for the pinning behavior of trapped flux, as well as hydrogen segregation in cavity niobium. The author wishes to present to the superconducting radio frequency (SRF) accelerator community the synthesis of experimental results scattered in the literature, completed with some personal results. The results of this effort provide a new perspective on recently published work in the domain of SRF cavity doping and sensitivity to trapped flux during cooldown. I will also try to draw whenever possible, some conclusions about other types of superconductors used for SRF applications including Nb=Cu thin films and to discuss their possible change of behavior with field or frequency. I will concentrate on surface and material science aspects since the experimental results on rf cavities have already been treated elsewhere.

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Section: A General Observationsmentioning

confidence: 99%

Influence of crystalline structure on rf dissipation in superconducting niobium

Antoine

2019

Phys. Rev. Accel. Beams

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“…The influence on transition temperature Tc seems more involved. Although it is well known that dislocations can change the superconducting transition temperature [152][153][154][155][156][157][158][159][160][161][162][163][164][165][166][167][168][169][170], the exact mechanism is unclear, even in simple Bardeen-Schrieffer-Cooper (BCS) superconductors (Table 1). The anisotropic superconducting gap [156-159] offers a possible theoretical foundation to explain c T with the presence of generic impurities [156][157][158]:…”

Section: Superconductivitymentioning

confidence: 99%

“…The anisotropic superconducting gap [157][158][159][160] offers a possible theoretical foundation to explain T c with the presence of generic impurities [157][158][159]: where T 0 c is the transition temperature of the pure case, η is the ratio between residual resistivity ρ 0K and phonon-limited resistivity (say, room-temperature ρ RT ), i.e. η = ρ 0K /ρ RT , a and b are empirical parameters.…”

Section: Superconductivitymentioning

confidence: 99%

“…However, problems remain. First, the original theories are derived for generic quenched impurities [157][158][159] with an elastic scattering impurity potential, but not for dislocations which have internal dynamics. Second, it is still challenging to obtain a theory using neither empirical parameters nor experimental parameters to compute T c .…”

Section: Superconductivitymentioning

confidence: 99%

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Quantized dislocations

Li¹

2019

J. Phys.: Condens. Matter

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A dislocation, just like a phonon, is a type of atomic lattice displacement but subject to an extra topological constraint. However, unlike the phonon which has been quantized for decades, the dislocation has long remained classical. This article is a comprehensive review of the recent progress on quantized dislocations, aka the "dislon" theory. Since the dislon utilizes quantum field theory to solve materials defects problems, we adopt a pedagogical approach to facilitate understanding for both materials science and condensed matter communities. After introducing a few preliminary concepts of dislocations, we focus on the necessity and pathways of dislocation's quantization in great detail, followed by the interaction mechanism between the dislon and materials electronic and phononic degrees of freedom. We emphasize the formality, the new phenomena, and the predictive power. Imagine the leap from classical lattice wave to quantized phonon; the dislon theory may open up vast opportunities to compute dislocated materials at a full quantum many-body level.

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“…3).can in principle be determined experimentally. The last term in (4.3) corresponds to the elastic energy stored by the dislocations in the state k'.…”

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confidence: 99%

The Micromagnetic Equations of a Superconductor

Seeger

Kronmüller

1968

Physica Status Solidi (b)

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A general theory is developed for deformable superconductors containing both spontaneous strains due to the superconductivity and internal strains due to crystal defects. An intersection technique, involving five distinct states K, x′, x″, k′, and k, is employed to derive the micromagnetic equations of a superconductor (generalizations of the Ginsburg‐Landau equations) on the basis of finite strain theory.

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The Influence of Dislocations on Superconductivity

Cited by 8 publications

References 13 publications

Influence of crystalline structure on rf dissipation in superconducting niobium

Influence of crystalline structure on rf dissipation in superconducting niobium

Quantized dislocations

The Micromagnetic Equations of a Superconductor

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