Depinning frequency in a heavily neutron-irradiated MgB2 sample

Bonura, Marco; Gallitto, Aurelio Agliolo; Vigni, M. Li; Martinelli, A.

doi:10.1016/j.physc.2008.09.002

Cited by 12 publications

(9 citation statements)

References 38 publications

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“…A very important parameter of vortex dynamics is the depinning frequency, ω 0 , defined as the ratio of the restoring-pinning-force coefficient and the flux-line viscosity [29]; so ω 0 gives direct information of the pinning strength [30,31]. Our results show that on increasing the B 2 O 3 content the depinning frequency increases, demonstrating an increase of the pinning effectiveness.…”

Section: Introductionmentioning

confidence: 63%

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y1.6Ba2.3Cu3.3O7−x samples

Gallitto

Duca

Vigni

et al. 2012

Physica C: Superconductivity

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We report on the microwave surface resistance of melt-textured Y 1.6 Ba 2.3 Cu 3.3 O 7−x samples, doped with different amount of B 2 O 3 and, subsequently, irradiated by thermal neutrons at the fluence of 1.476 × 10 17 cm −2 . The microwave surface resistance has been measured as a function of temperature and DC magnetic field. The experimental results are quantitatively discussed in the framework of the Coffey and Clem theory, properly adapted to take into account the d-wave nature of cuprate superconductors. By fitting the experimental data at zero DC field, we have highlighted the effects of the induced defects in the general properties of the samples, including the intergranular region. The analysis of the results obtained at high DC fields allowed us to investigate the fluxon dynamics and deduce the depinning frequency; in particular, we have shown that the addition of B 2 O 3 up to 0.1 wt% increases the effectiveness of the defects to hinder the fluxon motion induced by the microwave current.

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Section: Introductionmentioning

confidence: 63%

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y1.6Ba2.3Cu3.3O7−x samples

Gallitto

Duca

Vigni

et al. 2012

Physica C: Superconductivity

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“…24. In this work, we show that broadband measurements of the permeability at different microwave powers allow determining the depinning frequencies in the cases when different defects are present.…”

Section: Introductionmentioning

confidence: 70%

“…The depinning frequency (similarly to critical current) is determined by the details of vortex pinning. 24 In particular, it is very different in bulk and film superconductors; 31 in the case of films, it strongly depends on the film thickness approaching from the MHz (bulk superconductors) to GHz range for thin films. 23 Each type of defects has its own f d , therefore one can expect successive depinning of different defects.…”

Section: Resultsmentioning

confidence: 99%

Flux avalanches triggered by microwave depinning of magnetic vortices in Pb superconducting films

et al. 2011

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We observe abrupt changes in broadband microwave permeability of thin Pb superconducting films as functions of the microwave frequency and intensity, as well as of external magnetic field. These changes are attributed to vortex avalanches generated by microwave induced depinning of vortices close to the sample edges. We map the experimental results on the widely used theoretical model assuming reversible response of the vortex motion to ac drive. It is shown that our measurements provide an efficient method of extracting the main parameter of the model-depinning frequencies-for different pinning centers. The observed dependences of the extracted depinning frequencies on the microwave power, magnetic field, and temperature support the idea that the flux avalanches are generated by microwave induced thermomagnetic instabilities.

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“…All the calculations have been performed using T = T c / 2, B c2 = 15 i c , ω 0 /ω = 1 , λ 0 / δ 0 = 10 −2 . The ω 0 /ω ratio is chosen to be illustrative of high temperature superconductor not to describe a specific sample and is assumed to be constant in the whole field range investigated 23.…”

Section: Resultsmentioning

confidence: 99%

Study of microwave surface resistance of type‐II superconductors carrying transport current

Yıldız

İnanır

Kölemen

2010

Physica Status Solidi (b)

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We investigate the microwave surface resistance of an infinitely long type-II superconductor in the critical state carrying transport DC current, in the absence and in the presence of external magnetic fields. Calculations include both different cooling processes and various current and field arrangements.Theoretical results in field-cooled sample show that the microwave surface resistance exhibits an initial slow variation followed by a faster one above a threshold current value. This occurs when the current induced magnetic field generates fluxons of opposite directions on the two sample edges.

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Depinning frequency in a heavily neutron-irradiated MgB2 sample

Cited by 12 publications

References 38 publications

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y1.6Ba2.3Cu3.3O7−x samples

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y1.6Ba2.3Cu3.3O7−x samples

Flux avalanches triggered by microwave depinning of magnetic vortices in Pb superconducting films

Study of microwave surface resistance of type‐II superconductors carrying transport current

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