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

Pautrat, Alain; Goupil, Christophe; Simon, Ch.; Charalambous, D.; Forgan, E. M.; Lazard, G.; Mathieu, P.; Brûlet, Annie

doi:10.1103/physrevlett.90.087002

Cited by 28 publications

(39 citation statements)

References 14 publications

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“…Since the existence and the shape of this nonlinear part is found strongly sample dependent, the role of homogeneity of the critical current at the sample scale can be important. 6,8 In addition to the small shear modulus of the VL, this causes a depinning of large slices of vortices and the global nonlinear response can be explained by a sum of small linear regions. In the case of strong disorder and moderate velocity ͑close to the depinning threshold͒, a large number of dislocations can lead to plasticity.…”

Section: Introductionmentioning

confidence: 98%

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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Section: Introductionmentioning

confidence: 98%

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

Pautrat

Scola

2009

Phys. Rev. B

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“…This is in contrast to the case of the colloidal system where direct collisions between the particles dominate the dynamics. We first studied a Corbino disk (CD) [14][15][16][17][18] where, by applying a radial ac current, the vortices are rotated back and forth around the center of the sample by exerting a frustrated Lorentz force inversely proportional to the radius of rotation [13,19]. The average vortex velocity passing between the voltage contacts placed radially is detected from voltage V. Under an increase in the displacement amplitude d of vortices per cycle [13], we have found the threshold displacement d c for RIT as the onset of flow noise S V in the steady state.…”

Section: Introductionmentioning

confidence: 99%

Memory formation and evolution of the vortex configuration associated with random organization

et al. 2017

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We study the general phenomenon of random organization using a vortex system. When a periodic shear with a small shear amplitude d inp is applied to many-particle (vortex) assemblies with a random distribution, the particles (vortices) gradually self-organize to avoid future collisions and transform into an organized configuration. This is detected from the time-evolution of the voltage V t ( ) (average velocity) that increases towards a steady-state value. From the subsequent readout measurements of V t ( ) using various shear amplitudes, we find that the information of the input shear amplitude d inp is memorized in the configuration of the vortex distributions in the transient as well as the steady state, and that it is readable. We also find that the transient vortex configuration formed during random organization is not microscopically homogeneous but consists of disordered and organized regions.

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“…It is nevertheless quite reasonable to estimate that no bulk current is present for I Ͻ I c and that a bulk current, roughly ͑I − I c ͒, is observed for I Ͼ I c . The observed linear V͑I͒ curve 16 Top, for different velocities after the equilibrium disordered state. Bottom, for different velocities after the frozen ordered state.…”

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confidence: 97%

“…Bulk and surface currents can thus be distinguished ͑see Ref. 16 for details͒. The corresponding variation of I bulk as function of the applied current I is shown in Fig.…”

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confidence: 99%

Metastable states of a flux-line lattice studied by transport and small-angle neutron scattering

et al. 2005

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Flux-line lattice ͑FLL͒ states have been studied using transport measurements and small-angle neutron scattering in low-T c materials. In Pb-In, the bulk dislocations in the FLL do not influence the transport properties. In Fe-doped NbSe 2 , transport properties can differ after a field cooling ͑FC͒ or a zero field cooling ͑ZFC͒ procedure, as previously reported. The ZFC FLL is found ordered with narrow Bragg peaks and is linked to a linear V͑I͒ curve and to a superficial critical current. The FC FLL pattern exhibits two Bragg peaks and the corresponding V͑I͒ curve shows an S-shape. This can be explained by the coexistence of two ordered FLLs slightly tilted from the applied field direction by different superficial currents. These currents are wiped out when the transport current is increased.

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

Cited by 28 publications

References 14 publications

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

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

Memory formation and evolution of the vortex configuration associated with random organization

Metastable states of a flux-line lattice studied by transport and small-angle neutron scattering

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