0000000000653477

AUTHOR

J. I. Vestgården

showing 3 related works from this author

Irreversibility of the threshold field for dendritic flux avalanches in superconductors

2010

Hysteretic effects are seen in the upper and lower threshold fields for the appearance of dendritic flux instabilities, first explained in Yurchenko et al. [Phys. Rev. B 76 (2007) 092504], in NbN-films. We have measured the threshold fields at increasing and decreasing applied fields at different temperatures and proposed a mechanism explaining how the hysteresis arises by analyzing the field profiles inside the sample.

SuperconductivityPhysicsField (physics)Condensed matter physicsEnergy Engineering and Power TechnologyFluxCondensed Matter PhysicsInstabilityMagnetic fluxElectronic Optical and Magnetic MaterialsHysteresisLower thresholdCondensed Matter::SuperconductivityElectrical and Electronic EngineeringPhysica C: Superconductivity
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Metal frame as local protection of superconducting films from thermomagnetic avalanches

2016

Thermomagnetic avalanches in superconducting films propagating extremely fast while forming unpredictable patterns, represent a serious threat for the performance of devices based on such materials. It is shown here that a normal-metal frame surrounding a selected region inside the film area can provide efficient protection from the avalanches during their propagation stage. Protective behavior is confirmed by magneto-optical imaging experiments on NbN films equipped with Cu and Al frames, and also by performing numerical simulations. Experimentally, it is found that while conventional flux creep is not affected by the frames, the dendritic avalanches are partially or fully screened by them…

Materials sciencemetal framesthermomagnetic avalanchesFOS: Physical sciencesGeneral Physics and AstronomyFluxchemistry.chemical_element02 engineering and technology01 natural sciencesSuperconductivity (cond-mat.supr-con)AluminiumCondensed Matter::Superconductivity0103 physical sciences010306 general physicsSuperconductivitysuperconducting filmsResistive touchscreenta114Condensed matter physicsCondensed Matter - SuperconductivityConductanceThermomagnetic convection021001 nanoscience & nanotechnologyAvalanche breakdownlcsh:QC1-999Creepchemistry0210 nano-technologylcsh:PhysicsAIP Advances
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Energy of dendritic avalanches in thin-film superconductors

2018

A method for calculating stored magnetic energy in a thin superconducting film based on quantitative magneto-optical imaging is developed. Energy and magnetic moment are determined with these calculations for full hysteresis loops in a thin film of the superconductor NbN. Huge losses in energy are observed when dendritic avalanches occur. Magnetic energy, magnetic moment, sheet current and magnetic flux distributions, all extracted from the same calibrated magneto-optical images, are analyzed and discussed. Dissipated energy and the loss in moment when dendritic avalanches occur are related to each other. Calculating these losses for specific spatially-resolved flux avalanches is a great ad…

Materials sciencemedical imagingGeneral Physics and Astronomyclassical electromagnetism02 engineering and technologysuperconductors01 natural sciences7. Clean energysuprajohteetCondensed Matter::Superconductivity0103 physical sciencesThin film010306 general physicsEngineering & allied operationssuperconducting filmsSuperconductivityta114Magnetic energyCondensed matter physicsMagnetic momentDissipation021001 nanoscience & nanotechnologymagnetic hysteresislcsh:QC1-999Magnetic fluxMoment (mathematics)HysteresisFaraday effectthin filmsohutkalvotddc:6200210 nano-technologylcsh:Physics
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