Flux Pinning in Superconductors

Matsushita, Teruo

doi:10.1007/978-3-642-45312-0

Cited by 88 publications

(83 citation statements)

References 12 publications

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“…50 Here, the temperature dependencies are simply assumed as H c ðTÞ ¼ H c ð0Þ 1 À T=T c ð Þ and x ab ðTÞ ¼ x ab ð0Þ 1 À T=T c ð Þ À0:5 , and the field-dependent factor 1 À H=H c2 ð Þ 2 comes from the reduction in the condensation energy. 62 A detailed derivation of these equations is shown in Supplementary Figure S1. We focus on the additional pinning from NPs, assuming that the rest of the pinning landscape remains unchanged.…”

Section: Dramatically Higher J C With Nearly Isotropic Angular Dependmentioning

confidence: 99%

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

et al. 2017

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Because of pressing global environmental challenges, focus has been placed on materials for efficient energy use, and this has triggered the search for nanostructural modification methods to improve performance. Achieving a high density of tunable-sized second-phase nanoparticles while ensuring the matrix remains intact is a long-sought goal. In this paper, we present an effective, scalable method to achieve this goal using metal organic deposition in a perovskite system REBa 2 Cu 3 O 7 (rare earth (RE)) that enhances the superconducting properties to surpass that of previous achievements. We present two industrially compatible routes to tune the nanoparticle size by controlling diffusion during the nanoparticle formation stage by selecting the second-phase material and modulating the precursor composition spatially. Combining these routes leads to an extremely high density (8 × 10 22 m − 3 ) of small nanoparticles (7 nm) that increase critical currents and reduce detrimental effects of thermal fluctuations at all magnetic field strengths and temperatures. This method can be directly applied to other perovskite materials where nanoparticle addition is beneficial.

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Section: Dramatically Higher J C With Nearly Isotropic Angular Dependmentioning

confidence: 99%

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

et al. 2017

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“… has sometimes been used to fit data [1]. At temperatures close to T c , and for the limited range of LTS temperature data, this form can be difficult to distinguish from Equation (1).…”

Section: Temperature Dependence Of J Cmentioning

confidence: 99%

“…At temperatures close to T c , and for the limited range of LTS temperature data, this form can be difficult to distinguish from Equation (1). We therefore consider we have a well validated maximum entropy expression for J c (T).…”

Section: Temperature Dependence Of J Cmentioning

confidence: 99%

“…Remarkably the phenomenology of critical currents remains poorly understood. There are many models of critical currents [1][2][3][4] but these often fail to adequately reproduce basic features of experiments. In this paper we show how a maximum entropy approach results in a unified framework for understanding the phenomenology of critical currents in superconductors and provides insight that would be impossible to attain when working from deterministic models.…”

Section: Introductionmentioning

confidence: 99%

“…From a physics perspective we wish to connect critical currents with magnetic flux vortex behavior [1][2][3][4]. Flux vortices are the quantized magnetic fluxons which penetrate type II superconductors subjected to an applied magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Maximum Entropy Distributions Describing Critical Currents in Superconductors

Long

2013

Entropy

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Maximum entropy inference can be used to find equations for the critical currents (J c ) in a type II superconductor as a function of temperature, applied magnetic field, and angle of the applied field, θ or . This approach provides an understanding of how the macroscopic critical currents arise from averaging over different sources of vortex pinning. The dependence of critical currents on temperature and magnetic field can be derived with logarithmic constraints and accord with expressions which have been widely used with empirical justification since the first development of technical superconductors. In this paper we provide a physical interpretation of the constraints leading to the distributions for J c (T) and J c (B), and discuss the implications for experimental data analysis. We expand the maximum entropy analysis of angular J c data to encompass samples which have correlated defects at arbitrary angles to the crystal axes giving both symmetric and asymmetric peaks and samples which show vortex channeling behavior. The distributions for angular data are derived using combinations of first, second or fourth order constraints on cot θ or cot . We discuss why these distributions apply whether or not correlated defects are aligned with the crystal axes and thereby provide a unified description of critical currents in superconductors. For J//B we discuss what the maximum entropy equations imply about the vortex geometry.

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