Thermally assisted flux flow at small driving forces

Kes, P.H.; Aarts, J.; Berg, Jaap van den; Beek, C.J. van der; Mydosh, J. A.

doi:10.1088/0953-2048/1/5/005

Cited by 576 publications

(179 citation statements)

References 21 publications

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“…In many studies, the vortex liquid resistivity is described by a thermally activated flux flow (TAFF) model, q(T, H) ¼ q n exp (U * /k B T), 21 where q n is the normal state resistivity and k B is the Boltzmann constant. By using the TAFF model, we obtained the activation energy, U , the correction factor A is between 24-33, 21-32, and 20-28 for the BaK-122, BaCo-122, and BaNi-122 single crystals, respectively.…”

Section: -3mentioning

confidence: 99%

Flux pinning and vortex transitions in doped BaFe2As2 single crystals

Ghorbani

Wang

Shabazi

et al. 2012

Applied Physics Letters

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The vortex liquid-to-glass transition has been studied in Ba0.72K0.28Fe2As2 (BaK-122), Ba(Fe0.91Co0.09)2As2(BaCo-122), and Ba(Fe0.95Ni0.05)2As2(BaNi-122) single crystal with superconducting transition temperature, Tc = 31.7, 17.3, and 18 K, respectively, by magnetoresistance measurements. For temperatures below Tc, the resistivity curves were measured in magnetic fields within the range of 0 ≤ B ≤ 13 T, and the pinning potential was scaled according to a modified model for vortex liquid resistivity. Good scaling of the resistivity ρ(B, T) and the effective pinning energy U0(B,T) were obtained. The vortex state is three-dimensional at temperatures lower than a characteristic temperature T*. The vortex phase diagram was determined based on the evolution of the vortex-glass transition temperature Tg with magnetic field and the upper critical field, Hc2. We found that non-magnetic K doping results in a high glass line close to the Hc2, while magnetic Ni and Co doping causes a low glass line which is far away from the Hc2. Our results suggest that non-magnetic induced disorder is more favourable for enhancement of pinning strength compared to magnetic induced disorder. Our results show that the pinning potential is responsible for the difference in the glass states.

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Section: -3mentioning

confidence: 99%

Flux pinning and vortex transitions in doped BaFe2As2 single crystals

Ghorbani

Wang

Shabazi

et al. 2012

Applied Physics Letters

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“…3,4 Near the transition between the glassy and the liquid vortex phases the electronic conductivity obeys scaling laws 1,2 and far above the transition the motion of the vortex liquid is diffusive. [5][6][7] The existence of a scaling regime for the linear, frequency-dependent conductivity [8][9][10] ( ) and the nonlinear dc conductivity 11,12 ( j) is firmly established. Though these experimental findings in transport quantities support the existence of a vortex glass transition, measurements of thermodynamic variables have not shown an indication of a phase transition.…”

Section: Introductionmentioning

confidence: 99%

“…The thermally activated hopping of vortex bundles out of their pinning potentials results in a linear current-voltage characteristic at low currents. 14 Using the linear current voltage characteristic Kes et al 5 and Geshkenbein et al 15 developed a simple theory for the ac response of a superconducting sample that is described as a normal conductor with a frequency-independent resistivity of thermally activated form ͑TAFF͒. This theory was extended by Coffey and Clem 6 and Brandt 7 to include pinning effects, flux flow, and losses due to the normal fluid component.…”

Section: Introductionmentioning

confidence: 99%

Percolative vortex motion in high-temperature superconductors

Ziese

1996

Phys. Rev. B

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A model for percolative vortex motion in inhomogeneous superconductors is introduced. Near the percolation threshold the linear, frequency-dependent electronic conductivity is found to obey scaling laws. The percolation model for vortex motion provides an alternative explanation to the experimental finding of scaling in the electronic conductivity that is conventionally attributed to a vortex glass transition. The critical exponents derived from simulations of bond percolation on three-dimensional lattices are in satisfying agreement with critical exponents obtained from the scaling analysis of the conductivity of YBa 2 Cu 3 O 7Ϫ␦ twinned single crystals and ceramics. The electronic conductivity is calculated in an effective medium approximation and is compared to experimental data.

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“…For magnetic materials with linear permeability µ(ω) = B/(µ 0 H), in these formulae µ 0 has to be replaced by µ(ω)µ 0 . A superconductor may exhibit such a linear response above a temperature where thermal depinning of vortices, or thermally assisted flux flow (TAFF) occurs (Kes et al 1989). …”

Section: Definition Of Ac Susceptibilitiesmentioning

confidence: 99%

Ac response of thin-film superconductors at various temperatures and magnetic fields

Brandt

2000

Philosophical Magazine B

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A common method for measuring the electromagnetic properties of superconductors is to measure their complex magnetic ac susceptibility χ as a function of frequency ω and amplitude H 0 , and of temperature T and applied dc magnetic field H dc a as parameters. The basic theory of the linear χ(ω) and nonlinear χ(H 0 , ω) is outlined for various geometries, e.g. disks, rings, and strips of thin films or thicker platelets in a perpendicular magnetic field. It is shown how χ(ω) explicitly depends on the linear resistivity ρ ac (ω) = E/J or penetration depth λ ac (ω), and χ(H 0 , ω) on the nonlinear current-voltage law E(J, B) where E(r), J(r), B(r) are the local electric field, current density, and induction. The dependence of E(J, B) on T and on various material properties like pinning forces or pinning energies, structural defects and granularity, leads to an implicit dependence of χ on these parameters.

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Thermally assisted flux flow at small driving forces

Cited by 576 publications

References 21 publications

Flux pinning and vortex transitions in doped BaFe2As2 single crystals

Flux pinning and vortex transitions in doped BaFe2As2 single crystals

Percolative vortex motion in high-temperature superconductors

Ac response of thin-film superconductors at various temperatures and magnetic fields

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