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Merithew, R. D.; Rabin, Michael W.; Weissman, M. B.; Higgins, M. J.; Bhattacharya, S.

doi:10.1103/physrevlett.77.3197

Cited by 53 publications

(68 citation statements)

References 16 publications

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“…We stress that this latter interpretation was proposed for the peculiar case of the peak effect in N bSe 2 , where two macroscopic critical current states coexist in the sample ( [12,13] and references herein), and where the large noise values are coming from the kinetic between these two states. This was shown to correspond to non-Gaussian noise by a second spectrum analysis [14]. No such peculiar features are observed in our samples where the noise is observed to be Gaussian and has been verified stationary using the same high order statistics method.…”

Section: Resultsmentioning

confidence: 71%

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Scola¹,

Pautrat²,

Goupil³

et al. 2006

Phys. Rev. B

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We report on critical currents and voltage noise measurements in Niobium strips in the superconducting state, in the presence of a bulk vortex lattice (B < BC2) and in the surface superconducting state (Bc2 < B < BC3). For homogeneous surfaces, the correlation length of the current fluctuations can be associated with the electromagnetic skin depth of vortex superficial instabilities. The modification of the surface state by means of low energy irradiation induces a strong modification of the critical current and of the noise. The appearance of a corner frequency in the spectral domain can be linked with the low wave-vectors of the artificial corrugation. Since this latter occurs only for B < BC2, we propose that the long-range interactions allow the correlation length to extend up to values imposed by the surface topography.PACS numbers: 71.27.+a,72.70.+m,72.20.My Noise measurements are powerful tools to go inside the origin of the vortex pinning, and of the dynamical interactions between the vortex lattice and the sample disorder. This noise, generated during the lattice flow, is called the flux-flow noise [1]. It is generally characterized by the shape of its spectral density, and by its power. As it is often proposed in noise analysis, it is convenient to define a correlation length, within which the fluctuations are correlated. This defines the fluctuator of the system. To the extent that the fluctuators are independent and that the system is large enough, the correlation length can be calculated from the noise power via an usual statistical averaging (the central limit theorem) [2]. Recently, it was shown that no difference can be observed between the flux-flow noise in the mixed state and in the surface superconducting state of a Niobium slab [3]. In other words, the same fluctuator is present with or without a bulk vortex lattice, showing clearly its superficial origin. The coupling to the bulk was shown to be due to the conservation of the total current. This confirms previous auto and cross correlation experiments of both flux and voltage noises [4], and explains the insensivity of the low frequency noise to bulk perturbations [5], in Pb-In alloys. In these experiments, two parameters, the normalized spectrum of the fluctuator and its correlation length, are experimentally justified but are not explained [3,4]. If the fluctuator is of superficial origin, it should be possible to induce notable changes in the noise characteristics after some surface treatments. A following change in the noise spectral density, the noise power, or eventually in the underlying statistics, would give some clues to understand the spectrum and the fluctuator origins. Wherever it takes place, it has been made clear for years that the existence of flux-flow noise is intimately linked to the nature of the relevant disorder, i.e. to the vortex pinning. In the conclusion of his review article, Clem states that such a flux-flow noise theory " should be intimately related to an appropriate theory of critical current density " [1]...

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Section: Resultsmentioning

confidence: 71%

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Scola¹,

Pautrat²,

Goupil³

et al. 2006

Phys. Rev. B

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“…This can result in large noise signals [36] associated with a small number of fluctuators [36,53], intermediate structure in the ac susceptibility as a function of T [31,34], a stepwise expulsion of vortices [54], strong thermal instabilities [36,55] and a host of other phenomena specific to this phase [35], all features of the experimental data, which are hard to rationalize in other pictures.…”

Section: Much Theoretical Attention Hasmentioning

confidence: 95%

“…Experiments see a substantial enhancement in noise within the peak regime [53,75], a feature also seen in the ac susceptibility noise [33]. This noise is profoundly non-Gaussian in a regime where the PE is strongest; the number of independent fluctuators contributing to this noise turns out to be small [53].…”

Section: Universal Phase Diagram For Disordered Type-ii Supercondmentioning

confidence: 99%

“…It is thus unlikely that the glassy phase obtained at low temperatures and elevated field values is a true phase-coherent vortex glass, in the sense of the original proposal [11]. However, many experiments in the peak effect regime of low and high-T c materials show that the multi-domain glass which intervenes between the BrG and the DL phases has strongly glassy properties [31,32,36,53,[74][75][76]. The data on low-T c systems favours an equilibrium transition [35] proposal.…”

Section: Universal Phase Diagram For Disordered Type-ii Supercondmentioning

confidence: 99%

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Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Menon

2002

Phys. Rev. B

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A general phenomenology for phase behaviour in the mixed phase of type-II superconductors with weak point pinning disorder is outlined. We propose that the "Bragg glass" phase generically transforms via two separate thermodynamic phase transitions into a disordered liquid on increasing the temperature. The first transition is into a glassy phase, topologically disordered at the largest length scales; current evidence suggests that it lacks the longranged phase correlations expected of a "vortex glass". This phase has a significant degree of short-ranged translational order, unlike the disordered liquid, but no quasi-long range order, in contrast to the Bragg glass. This glassy phase, which we call a "multi-domain glass", is confined to a narrow sliver at intermediate fields, but broadens out both for much larger and much smaller field values. The multi-domain glass may be a "hexatic glass"; alternatively, its glassy properties may originate in the replica symmetry breaking envisaged in recent theories of the structural glass transition. Estimates for translational correlation lengths in the multi-domain glass indicate that * Email:menon@imsc.ernet.in 1 they can be far larger than the interline spacing for weak disorder, suggesting a plausible mechanism by which signals of a two-step transition can be obscured. Calculations of the Bragg glass-multi-domain glass and the multidomain glass-disordered liquid phase boundaries are presented and compared to experimental data. We argue that these proposals provide a unified picture of the available experimental data on both high-T c and low-T c materials, simulations and current theoretical understanding.

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“…For high-T c superconductors, we chose a slightly different approach; local-density-noise (LDN) measurement [26][27][28]. Observation of low-frequency-noise has been a popular tool to study the vortex motion both in conventional and high-T c superconductors [29][30][31][32][33], and such noise has been considered to have some relationship with various low-frequency phenomena [34,35]. This conduction noise represents the velocity fluctuation averaged over a macroscopic sample.…”

Section: Introductionmentioning

confidence: 99%

Location-sensitive measurement of the local fluctuation of driven vortex density inBi2Sr2CaCu
Maeda
¹
,
Tsuboi
²
,
Abiru
³

et al. 2002
Phys. Rev. B
24
3
14
0
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To investigate the dynamics of driven vortices in superconductors, noise in the local vortex density was investigated in the mixed state of a high-Tc superconductor, Bi2Sr2CaCu2Oy, using a twodimensional electron gas (2DEG) micro-Hall probe array. We studied the cross-correlation function, together with the auto-correlation function, both parallel and perpendicular to the direction of flow of the vortices. The broadband noise (BBN) did not have large spatial correlations. This suggests that the BBN is due to the fluctuation of the local vortex density generated by bulk pinning centers under the area of each probe. On the other hand, the narrow-band noise (NBN) (with the the time scale of the transit time of vortices) had large translational correlations. These definitely shows that the NBN was generated by semimacroscopic imperfections like the surface, and macroscopic line defects etc.. In relation to the dynamic phase diagram, large BBN was observed when the vortices started moving. The dependence of the spatial correlations on the direction of the array relative to the direction of the driving current suggested that plastic flow was present when the large BBN was observed. The gross features of our data agree well with some of the theoretically proposed dynamical phase diagrams of vortices in superconductors.

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Persistent Metastable States in Vortex Flow at the Peak Effect in NbSe2

Cited by 53 publications

References 16 publications

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Location-sensitive measurement of the local fluctuation of driven vortex density inBi2Sr2CaCu
Maeda
¹
,
Tsuboi
²
,
Abiru
³

et al. 2002
Phys. Rev. B
24
3
14
0
View full text Add to dashboard Cite

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Persistent Metastable States in Vortex Flow at the Peak Effect in NbSe2

Cited by 53 publications

References 16 publications

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Experimental study of the correlation length of critical-current fluctuations in the presence of surface disorder: Probing vortex long-range interactions

Phase behavior of type-II superconductors with quenched point pinning disorder: A phenomenological proposal

Location-sensitive measurement of the local fluctuation of driven vortex density inBi2Sr2CaCuMaeda1, Tsuboi2, Abiru3 et al. 2002Phys. Rev. B243140View full textAdd to dashboardCite

Contact Info

Product

Resources

About

Location-sensitive measurement of the local fluctuation of driven vortex density inBi2Sr2CaCu
Maeda
¹
,
Tsuboi
²
,
Abiru
³

et al. 2002
Phys. Rev. B
24
3
14
0
View full text Add to dashboard Cite