Small angle neutron scattering and vortex lattice dynamical phase diagram

Goupil, Christophe; Pautrat, Alain; Simon, Ch.; Kealey, P. G.; Forgan, E. M.; Johnson, S. T.; Lazard, G.; Plaçais, Bernard; Simon, Y.; Mathieu, P.; Cubitt, R.; Dewhurst, C. D.

doi:10.1016/s0921-4534(00)00762-0

Cited by 11 publications

(18 citation statements)

References 14 publications

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“…This is expected if the bulk current is homogeneous. Consistently, and because the curvature of the Bragg planes is in the x direction, the widths of the rocking curves (y direction, not shown in the figures) do not change with current, within the error of the fits [13]. Figures 3(a) and 3(b) show both the VI curves and the broadening of the rocking curves as a function of the current for two different surface states of the first sample.…”

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confidence: 60%

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Distribution of Transport Current in a Type-II Superconductor Studied by Small-Angle Neutron Scattering

et al. 2003

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We report small-angle neutron scattering measurements on the vortex lattice in a PbIn polycrystal in the presence of an applied current. Using the rocking curves as a probe of the distribution of current in the sample, we observe that vortex pinning is due to the surface roughness. This leads to a surface current that persists in the flux-flow region. We show the influence of surface treatments on the distribution of this current.

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confidence: 60%

“…This ''powder pattern'' from the FLL is certainly caused by the polycrystalline nature of the Pb-In sample. However, FLL order can be obtained by passing a current larger than critical [13] or by choosing a single crystal of Pb-In [14]. Polycrystals and single crystals of Pb-In exhibit the same VI curve for the same surface treatment.…”

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confidence: 99%

Distribution of Transport Current in a Type-II Superconductor Studied by Small-Angle Neutron Scattering

et al. 2003

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“…Note neutron-scattering experiments in conventional low-T c materials indicate also that the VL is much more regular than expected for a model of independent flux bundles motion at the beginning of its motion. 7,26,27 …”

Section: B Discussionmentioning

confidence: 99%

Narrow-band noise due to the moving vortex lattice in superconducting niobium

Pautrat

Scola

2009

Phys. Rev. B

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We report measurements of voltage noise due to vortex motion in Niobium, a conventional low-T c superconductor. A coherent oscillation leading to narrow-band noise ͑NBN͒ is evidenced. Its characteristic frequency is a linear function of the overcritical transport current in the flux-flow regime, and hence scales as the main velocity of the vortex flow. The associated length scale is not the intervortex distance but the width of the sample, indicating temporal coherence at a large scale. NBN is also observed in the nonlinear part of the V͑I͒ at the onset of depinning, in apparent disagreement with a stochastic creep motion of flux bundles. NBN exists in the peak effect region, showing that long-range temporal correlations are preserved in this regime.

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“…It must be emphasized that neutron-scattering experiments carried out in a similar sample give the evidence of a well ordered VL ͑crystallinelike͒ in the same conditions. 19 Thus we study the noise signature of a moving crystal of vortices or a moving Bragg glass of vortices, i.e., the high velocity ordered state seen in simulations. Nevertheless, it is important to realize that large velocity fluctuations in the two directions ͑both longitudinal and transverse to the motion͒ are present in this regime.…”

Section: A Velocity Fluctuation Measurementmentioning

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Longitudinal and transverse noise in a moving vortex lattice

Scola¹,

Pautrat²,

Goupil³

et al. 2005

Phys. Rev. B

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We have studied the longitudinal and the transverse velocity fluctuations of a moving vortex lattice ͑VL͒ driven by a transport current. They exhibit both the same broad spectrum and the same order of magnitude. These two components are insensitive to the velocity and to a small bulk perturbation. This means that no bulk averaging over the disorder and no VL crystallization are observed. This is consistently explained referring to a previously proposed noisy flow of surface current whose elementary fluctuator is measured isotropic.

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Small angle neutron scattering and vortex lattice dynamical phase diagram

Cited by 11 publications

References 14 publications

Distribution of Transport Current in a Type-II Superconductor Studied by Small-Angle Neutron Scattering

Distribution of Transport Current in a Type-II Superconductor Studied by Small-Angle Neutron Scattering

Narrow-band noise due to the moving vortex lattice in superconducting niobium

Longitudinal and transverse noise in a moving vortex lattice

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