Voltage noise of YBa2Cu3O7−δ films in the vortex-liquid phase

Wöltgens, P. J. M.; Dekker, Cees; Gielkens, S.W.A.; Wijn, H. W. de

doi:10.1016/0921-4534(95)00195-6

Cited by 24 publications

(17 citation statements)

References 28 publications

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“…where ͑for zϾ0.315) g(z)ϭ(1Ϫz) 3 For magnetic fields below ϳ0.65 T the LO theory does not explain the magnetoresistance data, and R is smaller than R FF . This indicates that the vortices are slowed down by experiencing a pinning potential.…”

Section: Magnetoresistance and Current-voltage Characteristicsmentioning

confidence: 99%

“…2 Samples used in these studies were mainly polycrystalline conventional superconductors with appreciable pinning and nonlinear V(I) characteristics up to very close to B c2 . Noise experiments have also been carried out on high-T c superconductors, [3][4][5] which are in a ''liquid'' state of negligible pinning over a large portion of the magnetic field vs temperature plane, displaying linear V(I) curves. However, the intricate anisotropic character of vortex matter in these compounds is a serious obstacle to the understanding of the mechanisms that contribute to voltage noise related to motion of vortices against a weak pinning potential.…”

Section: Introductionmentioning

confidence: 99%

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Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

et al. 2002

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We report high-resolution measurements of voltage ͑V͒ noise in the mixed state of micrometer-sized thin films of amorphous Nb 0.7 Ge 0.3 , which is a good representative of weak-pinning superconductors. There is a remarkable difference between the noise below and above the irreversibility field B irr . Below B irr , in the presence of measurable pinning, the noise at small applied currents resembles shot noise, and in the regime of flux flow at larger currents decreases with increasing voltage due to a progressive ordering of the vortex motion. At magnetic fields B between B irr and the upper critical field B c2 flux flow is present already at vanishingly small currents. In this regime the noise scales with (1ϪB/B c2 ) 2 V 2 and has a frequency ͑f͒ spectrum of 1/f type. We interpret this noise in terms of the properties of strongly driven depinned vortex systems at high vortex density.

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Section: Magnetoresistance and Current-voltage Characteristicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

et al. 2002

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“…The measured noise is due to the energy dissipation generated by the vortex bundles motion [6]. At low temperature, the pinning force is more important than the thermal activation.…”

Section: Methodsmentioning

confidence: 99%

“…The particular interest is the flux noise [1][2][3][4][5][6] observed in the thermally activated vortex motion in the high-T c superconducting thin films. Recently many results found [2][3][4] in the literature indicate that the flux noise at low frequencies f increased substantially when the density of fluctuating vortices is increased.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the noise voltage in high‐T_c superconducting thin films

Labrag

Bghour

Abaragh

et al. 2006

Phys. Status Solidi (c)

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We measured the noise spectral density S V variations of YBa 2 Cu 3 O 7-δ films in a large range of frequencies f 0.1-1000 Hz, temperature T and under the effect of a magnetic field up to 14 T. in order to clarify the origin of the noise observed in thin films deposed by the laser ablation method on the surface (001) of SrTiO 3 substrate, the noise power spectral density S(f,T) of the noise variations versus temperature and frequency is presented in Fig. 3 for H = 14 T parallel to the ab plane, I = 3 nA. We can observe from this result that the noise spectral density S V (T) shows a marked enhancement near T c the temperature superconducting transition. Our results suggested that the main source for the noise in the mixed state is the thermally activated vortex motion in the high-T c superconducting thin films.

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“…This approach has been widely used in explaining 1 / f type of noise not only in the conduction of normal electrons 15,16 but also in vortex-motion-generated dissipation. 3,13,14 However, in the latter studies, the arguments in favor of a distribution of relied on somewhat heuristic assumptions, such as the presence of vortex bundles 13 or of a mixture of depinned solid and "liquid" vortex phases. 3,14 In our case, a range of follows straightforwardly from a coexistence of distinct E-dependent vortex states.…”

Section: Discussionmentioning

confidence: 99%

1∕fflux flow noise due to a coexistence of qualitatively different vortex states

et al. 2007

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We investigate the vortex-motion voltage noise in a hybrid structure consisting of a weak-pinning amorphous Nb 0.7 Ge 0.3 microbridge on top of which a strong-pinning, longitudinal Nb line with a narrow interruption in the middle is added. The Nb part enforces a branching of the applied current, causing a modulation of the current density within the Nb 0.7 Ge 0.3 , where vortex motion induces a voltage. When the Nb 0.7 Ge 0.3 is sufficiently dissipative, the modulation is strong and the vortex dynamics is spatially dependent. Under these circumstances, the distribution function for normal excitations in vortex cores varies considerably over the sample, which results in a coexistence of distinct vortex states spreading from nearly equilibrium to strongly nonequilibrium ones. This leads to a range of characteristic times for the voltage fluctuations and, consequently, to the frequency ͑f͒ dependence of the noise being of 1 / f type. The noise originates in the fluctuations of the vortex-core size around the average set by the nonequilibrium effects in vortex motion.

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Voltage noise of YBa2Cu3O7−δ films in the vortex-liquid phase

Cited by 24 publications

References 28 publications

Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

Analysis of the noise voltage in high‐T_c superconducting thin films

1∕fflux flow noise due to a coexistence of qualitatively different vortex states

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Voltage noise of YBa2Cu3O7−δ films in the vortex-liquid phase

Cited by 24 publications

References 28 publications

Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

Vortex motion noise in micrometer-sized thin films of the amorphousNb0.7Ge0.3weak-pinning superconductor

Analysis of the noise voltage in high‐Tc superconducting thin films

1∕fflux flow noise due to a coexistence of qualitatively different vortex states

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Analysis of the noise voltage in high‐T_c superconducting thin films