Mixed state microwave resistivity of cuprate superconductors

Pompeo, Nicola; Muzzi, L.; Sarti, S.; Marcon, R.; Fastampa, R; Giura, M.; Boffa, M.; Cucolo, M. C.; Cucolo, A. M.; Camerlingo, C.; Silva, Enrico

doi:10.1016/j.jpcs.2005.10.014

“…In conventional superconductors, where the quasiparticle density of state (DOS) comes from the low-energy states localized in the vortex cores, α = 1; in superconductors with lines of gap nodes, the DOS comes mostly from the continuous spectrum concentrated in proximity of the gap nodes outside the vortex core and, consistently with the calculations of Volovik [42], one can assume α = 1/2 for magnetic fields not close to H c2 . This assumption has been used to account for experimental results of fieldinduced mw losses in cuprate superconductors [43,44]. Contrary to what occurs in conventional superconductors, in which the magnetic-field-induced mw losses are mainly due to the fluxon motion, it has been shown that in HTS an important contribution comes from the field-induced pair breaking, related to the gap nodes and described by a √ B dependence.…”

Section: Field-induced Variation Of Rsmentioning

confidence: 99%

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

Gallitto

¹

,

Duca

²

,

Vigni

³

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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“…In conventional superconductors, where the quasiparticle density of state (DOS) comes from the low-energy states localized in the vortex cores, α = 1; in superconductors with lines of gap nodes, the DOS comes mostly from the continuous spectrum concentrated in proximity of the gap nodes outside the vortex core and, consistently with the calculations of Volovik [42], one can assume α = 1/2 for magnetic fields not close to H c2 . This assumption has been used to account for experimental results of fieldinduced mw losses in cuprate superconductors [43,44].…”

Section: Field-induced Variation Of Rsmentioning

confidence: 99%

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y_1.6Ba_2.3Cu_3.3O_7-x samples

Gallitto,

La Duca,

Vigni

et al. 2012

Preprint

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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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“…In both cases, the contribution of the field induced superfluid depletion cannot be neglected, at least in some temperature range. On the basis of the previous discussion of the theoretical expectations, we can isolate the quasiparticle/superfluid contribution from the vortex motion term by identifying the B-linear term in ∆r [11]. In this way, we determine η for the two cuprate materials under study (inset of Fig.…”

Section: Fixed Frequency Measurementsmentioning

confidence: 99%

Vortex Motion and Quasiparticle Resistivity in Superconductors at Microwave Frequencies

Sarti

¹

,

Amabile

²

,

Fastampa

³

et al. 2007

Acta Phys. Pol. A

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At nonzero frequencies both the normal and superfluid fractions, as well as moving vortices, contribute to the electrical transport, resulting in intricate expressions for the resistivity. We present an extended study of microwave resistivity data measured on YBa 2 Cu 3 O 7−δ , SmBa 2 Cu 3 O 7−δ , and MgB2 by means of a broad-band technique between 2 and 20 GHz and of a resonant system at 50 GHz. We discuss the main experimental fingerprints that allow one to identify the relevance of the different contributions from the measured microwave response as a function of frequency, temperature, and magnetic field. We show that the field-dependent superfluid/quasiparticles dynamics cannot be in general neglected with respect to the vortex motion, albeit its relative importance is different in different materials: in high temperature superconductors vortex motion prevails at high fields, but at low fields a significant superfluid/quasiparticle contribution exists (ascribed to the presence of lines of nodes). In MgB 2 the two contributions are comparable even at high fields. In this general frame, we derive from the measurements vortex and superfluid parameters in agreement with theoretical predictions and independent measurements.

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Mixed state microwave resistivity of cuprate superconductors

Cited by 4 publications

References 9 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

Effect of boron doping in the microwave surface resistance of neutron irradiated melt-textured Y_1.6Ba_2.3Cu_3.3O_7-x samples

Vortex Motion and Quasiparticle Resistivity in Superconductors at Microwave Frequencies

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