Nonlinear microwave response in field-cooled high-Tc and type II superconductors

Ciccarello, I.; Fazio, Claudio; Guccione, M.; Vigni, M. Li

doi:10.1016/0921-4534(89)90147-0

Cited by 35 publications

(22 citation statements)

References 13 publications

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“…At low magnetic fields and low temperatures, harmonic generation has been ascribed to nonlinear processes in weak links, impurities and intergrain-fluxon dynamics [17,18,19,20]. At magnetic fields higher than the lower critical field, when the weak links are decoupled, harmonic emission has been ascribed to intragrain-fluxon dynamics [21,22]. At temperatures near T c , modulation of the order parameter by the em field is the main source of nonlinearity [23,24,25].…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless, it has been reported that superconductors in the critical state exposed to pulsed mw fields exhibit odd as well as even-harmonic emission [22], even when H dc ≫ H ac . The mw SH emission by superconductors in the critical state has been discussed by Ciccarello et al [22], who have elaborated a phenomenological model, based on the Bean model, in which the additional hypothesis is put forward that superconductors in the critical state operate a rectification process of the mw input field. The process arises because of the inertia of the fluxon lattice to follow high-frequency fields.…”

Section: Discussionmentioning

confidence: 99%

“…Nonlinear electromagnetic response of both conventional and high-T c superconductors has been discussed by different authors [16,17,18,19,20,21,22,23,24,25]. Several mechanisms give rise to emission of signals oscillating at harmonic frequencies of the driving field.…”

Section: Discussionmentioning

confidence: 99%

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Surface-barrier effects in the microwave second-harmonic response of superconductors in the mixed state

et al. 2005

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Abstract. We report on transient effects in the microwave second-order response of different type of superconductors in the mixed state. The samples have contemporarily been exposed to a dc magnetic field, varying with a constant rate of 60 Oe/s, and a pulsed microwave magnetic field. The time evolution of the signal radiated at the second-harmonic frequency of the driving field has been measured for about 500 s from the instant in which the dc-field sweep has been stopped, with sampling time of ∼ 0.3 s. We show that the second-harmonic signal exhibits two relaxation regimes; an initial exponential decay, which endures roughly 10 s, and a logarithmic decay in the time scale of minutes. Evidence is given that the decay in the time scale of minutes is ruled by magnetic relaxation over the surface barrier.PACS. 74.25.Ha Magnetic properties -74.25.Nf Response to electromagnetic fields (nuclear magnetic resonance, surface impedance, etc.) -74

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Surface-barrier effects in the microwave second-harmonic response of superconductors in the mixed state

et al. 2005

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“…In any case, harmonic distortion is a peculiarity of the superconducting state; harmonic signals disappear whenever the SC goes into the normal state. It is widely accepted that, at temperatures not very near T c , the mechanisms that play the most important role are (i) nonlinear electromagnetic response of the weak-link matrix (at low magnetic fields) [11,[35][36][37] and (ii) motion of Abrikosov vortices in the critical state (at H > H c1g ) [5,12,38].…”

Section: Resultsmentioning

confidence: 99%

Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires

Gallitto¹,

Bonsignore²,

Vigni³

et al. 2011

Supercond. Sci. Technol.

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We discuss experimental results obtained using a tunable cylindrical coaxial cavity resonator constituted by an outer Cu cylinder and an inner bulk Bi 1.8 Pb 0.26 Sr 2 Ca 2 Cu 3 O 10+x cylinder. We have used this device to investigate the microwave response of the superconducting wire, both in the linear and nonlinear regimes. In particular, by tuning the different modes of the cavity to make them resonant at exactly harmonic frequencies, we have detected the power emitted by the superconductor at the second-and third-harmonic frequency of the driving field. The results obtained in the nonlinear regime, whether for the microwave surface impedance or the harmonic emission, are discussed in the framework of the models reported in the literature for granular superconductors. The use of this kind of device could be of great interest to investigate and characterize wires of large dimensions, to be used for implementing superconducting-based microwave devices.

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“…Microwave SH emission by superconductors in the critical state has been ascribed to a rectification process of the mw field operated by the superconductor [6]. The process arises because of the inertia of the fluxon lattice to follow high-frequency fields.…”

Section: Discussionmentioning

confidence: 99%

Time evolution of the microwave second-harmonic response of MgB2 superconductor

Gallitto

Vigni

Vaglica

2004

Physica C: Superconductivity

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We report on transient effects in the microwave second-order response of two ceramic MgB 2 samples. The time evolution of the second-harmonic signal is investigated for about 500 s after the sample has been exposed to a variation of the dc magnetic field. We suggest that during the first seconds the response is determined by diffusive motion of fluxons, while in the time scale of minutes it is ruled by magnetic relaxation over the surface barrier.

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Nonlinear microwave response in field-cooled high-Tc and type II superconductors

Cited by 35 publications

References 13 publications

Surface-barrier effects in the microwave second-harmonic response of superconductors in the mixed state

Surface-barrier effects in the microwave second-harmonic response of superconductors in the mixed state

Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires

Time evolution of the microwave second-harmonic response of MgB2 superconductor

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