Irreversible dynamics of Abrikosov vortices in type-two superconductors

Pace, S.; Филатрелла, Г.; Grimaldi, Gaia; Nigro, A.

doi:10.1016/j.physleta.2004.06.048

Cited by 7 publications

(5 citation statements)

References 34 publications

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“…Our theoretical results compare well to a number of experimentally measured current-voltage characteristics [23][24][25][26][27] .…”

Section: Discussionsupporting

confidence: 78%

“…1; the free dissipative flow v = F L /η is approached only at very high velocities v v p v c . Experiments measuring the current-voltage, i.e., I-V , characteristic then should observe an excess-current characteristic V = R ff (I − I c ) with R ff the flux-flow resistivity; this type of characteristic has been widely measured in the past [23][24][25][26][27] and its microscopic derivation is the main purpose and result of this paper. In doing so, we prove the analogue of Coulomb's law of dry friction (describing the motion of a solid body sliding on a dry surface) for the case of strong vortex pinning in the dilute limit: In Amontons' first and second laws of friction, the friction force, corresponding to our F c , is given by the product of the friction coefficient k and the normal force F n , F f = kF n .…”

Section: ~Fmentioning

confidence: 99%

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Vortex dynamics in type-II superconductors under strong pinning conditions

2017

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We study effects of pinning on the dynamics of a vortex lattice in a type II superconductor in the strong-pinning situation and determine the force-velocity (or current-voltage) characteristic combining analytical and numerical methods. Our analysis deals with a small density np of defects that act with a large force fp on the vortices, thereby inducing bistable configurations that are a characteristic feature of strong pinning theory. We determine the velocity-dependent average pinning-force density Fp(v) and find that it changes on the velocity scale vp ∼ fp/ηa 3 0 , where η is the viscosity of vortex motion and a0 the distance between vortices. In the small pin-density limit, this velocity is much larger than the typical flow velocity vc ∼ Fc/η of the free vortex system at drives near the critical force-density Fc = Fp(v = 0) ∝ npfp. As a result, we find a generic excessforce characteristic, a nearly linear force-velocity characteristic shifted by the critical force-density Fc; the linear flux-flow regime is approached only at large drives. Our analysis provides a derivation of Coulomb's law of dry friction for the case of strong vortex pinning. PACS numbers: 74.25.F-, 74.25.Wx, 74.25.Sv arXiv:1709.03369v1 [cond-mat.supr-con]

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“…Our theoretical results compare well to a number of experimentally measured current-voltage characteristics [23][24][25][26][27] .…”

Section: Discussionsupporting

confidence: 78%

Section: ~Fmentioning

confidence: 99%

Vortex dynamics in type-II superconductors under strong pinning conditions

2017

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“…More likely are contributions of alternative dissipation mechanism for flux flow, like losses induced by irreversible entropy flux in the core vicinity, 38 by nonequilibrium generation and recombination of Cooper pairs around the vortex core, 39 or by nonequilibrium phenomena when vortices cross local pinning potentials. 40,41 From the first two models an increasing R f f with decreasing temperature is expected in contrast to the experimental observations presented in Fig. 6.…”

Section: H B Dependence Of R Ffcontrasting

confidence: 67%

“…It could be related to the smaller London penetration depth at lower temperatures causing a better defined caging potential with stronger caging pinning force. If flux-flow viscosity is strongly influenced by nonequilibrium phenomena of vortices crossing local pinning potentials, 40,41 should increase with this stronger caging pinning force resulting in a smaller R f f . The nearly missing or only slightly increasing R f f with B, in our case, differs from interstitial flow observed by Lange et al for a regular magnetic pinning array on lead.…”

Section: H B Dependence Of R Ffmentioning

confidence: 99%

Temperature-dependent matching in a flux-line lattice interacting with a triangular array of pinning centers without long-range order

et al. 2007

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A triangular array of nanoscaled artificial pinning centers ͑APCs͒ for magnetic flux lines is prepared into a Nb thin film. The APCs are formed by deposition of Nb onto a Si substrate covered with nanopillars with diameters of 20 nm and lattice constant a = 122 nm. The production of pillars is based on arrays of gold nanoparticles used as etching masks during reactively ion etching a Si substrate. In this way, the pattern of the original nanoparticle array is transferred onto the substrate. The Au nanoparticles in turn were prepared using the self-organization of inverse micelles formed by diblock copolymers, whose core is loaded with a gold precursor. The resulting lattice of APCs formed by the Si pillars perforating the Nb film mirrors the order of the micellar array which has triangular, short-range order, but loses its directional order for distances larger than about 4-8 lattice constants. Similar to the Little-Parks experiments with external magnetic fields perpendicular to the superconducting film, the resulting T c ͑B͒ curves show ⌬T c deviations. Those vanish for B larger than the first matching field B 1 indicating that no more than one single flux quantum can be captured at each APC, even at low temperatures. Moreover, integer and fractional matching effects in the critical current are observed within a wide temperature range. Two critical currents can be distinguished indicating different types of pinning mechanisms: Strong pinning at APCs and weaker pinning at interstitial sites accompanied by strong caging effects. A unique feature of such prepared samples is the surprising temperature dependence of the matching field for which a value of B 1 is observed close to T c , which, however, is shifted towards smaller values at lower temperatures. This effect is traced back to a temperature dependent averaging over differently ordered domains within the array of APCs.

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“…In particular the static and dynamic interaction between the vortex lattice and the material defects is an important key to determine the details of the current transport properties in the superconducting state [1], so that the study of the current-voltage (I-V) characteristics is a direct measurement of the force-velocity curve [2][3][4]. It has also been shown that the dynamic interaction between vortices and pinning centers changes the non equilibrium quasiparticle distribution and the vortex dynamics [2]. In the free flux flow motion Larkin and Ovchinnikov (LO) predicted a vortex critical velocity v * associated to the observable critical voltage V * = v * lB (l is the voltage tip distance, B is the external applied magnetic field) [5].…”

Section: Introductionmentioning

confidence: 99%