Experimental test of strong pinning and creep in current-voltage characteristics of type-II superconductors

Buchacek, Martin; Xiao, Zhili; Dutta, Surajit; Andrei, E. Y.; Raychaudhuri, Pratap; Geshkenbeǐn, V. B.; Blatter, G.

doi:10.1103/physrevb.100.224502

Cited by 11 publications

(8 citation statements)

References 28 publications

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“…The first task involves studying creep of isolated vortices, pinned by a single strong inclusion or columnar defect. In accordance with analytic predictions, an increase in temperature shifts the characteristic depinning current below J c , rounds the IV curves and affects the excess-current characteristic far beyond J c [58][59][60] . The next steps will involve studying multiple vortices, more defects, and mixed defect landscapes, which will indeed increase the complexity of the problem, warranting computational assistance.…”

Section: Transformative Opportunities a Vortex Creepsupporting

confidence: 81%

“…While conceptually simpler than weak collective pinning, it has taken significantly longer to develop a strong pinning formalism. With its completion in the early 2000s, the formalism enabled computing numerous physical observables, including the critical current 53,54 , the excess-current characteristic [55][56][57][58][59][60] , and the ac Campbell response [11][12][13][14] .…”

Section: A Fundamentals Of Vortex Pinningmentioning

confidence: 99%

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Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics

Eley,

Glatz,

Willa

2021

Preprint

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In superconductors, the motion of vortices introduces unwanted dissipation that is disruptive to applications. Fortunately, material defects can immobilize vortices, acting as vortex pinning centers, which engenders dramatic improvements in superconductor material properties and device operation. This has motivated decades of research into developing methods of tailoring the disorder landscape in superconductors to increase the strength of vortex pinning. Yet efficacious materials engineering still alludes us. The electromagnetic properties of real (disordered) superconducting materials cannot yet be reliably predicted, such that designing superconductors for applications remains a largely inefficient process of trial and error. This is ultimately due to large gaps in our knowledge of vortex dynamics: the field is challenged by the extremely complex interplay between vortex elasticity, vortex-vortex interactions, and material disorder.In this Perspective, we review obstacles and recent successes in understanding and controlling vortex dynamics in superconducting materials and devices. We further identify major open questions and discuss opportunities for transformative research in the field. This includes improving our understanding of vortex creep, determining and reaching the ceiling for the critical current, advanced microscopy to garner accurate structure-property relationships, frontiers in predictive simulations and the benefits of artificial intelligence, as well as controlling and exploiting vortices in quantum information applications.

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Section: Transformative Opportunities a Vortex Creepsupporting

confidence: 81%

Section: A Fundamentals Of Vortex Pinningmentioning

confidence: 99%

Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics

Eley,

Glatz,

Willa

2021

Preprint

View full text Add to dashboard Cite

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“…There is a striking similarity between the double-threshold V -I dependences in silicon MOSFET samples and those (with the voltage and current axes interchanged) in the type-II superconductors, where the existence of the vortex lattice has been firmly established [23,24,25,26,27]. An example of I-V characteristic in such a system is shown in Fig.…”

Section: Experimental Noise and Its Som Analysismentioning

confidence: 80%

Noise signal as input data in self-organized neural networks

Kagalovsky,

Nemirovsky,

Kravchenko

2022

Preprint

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Self-organizing neural networks are used to analyze uncorrelated white noises of different distribution types (normal, triangular, and uniform). The artificially generated noises are analyzed by clustering the measured time signal sequence samples without its preprocessing. Using this approach, we analyze, for the first time, the current noise produced by a sliding "Wigner-crystal"like structure in the insulating phase of a 2D electron system in silicon. The possibilities of using the method for analyzing and comparing experimental data obtained by observing various effects in solid-state physics and simulated numerical data using theoretical models are discussed.

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“…When including thermal fluctuations in the calculation of the pinning force density F pin , different jumps ∆e pin (t) in the pinning energy become relevant that depend on the time t evolution of the vortex state due to creep. While this relaxational time dependence leads to the decay of the persistent current density j(t), the corresponding velocity dependence leads to a rounding 14,15 of the transition 16 between pinned and dissipative states in the current-voltage characteristic; again the quantitative nature of the strong pinning description allows for a detailed comparison of the temperature-shifted and rounded excess-current characteristic predicted by theory with experimental data on superconducting films 17 .…”

Section: Introductionmentioning

confidence: 92%

Creep effects on the Campbell response in type II superconductors

Filippo¹,

Blatter²,

Geshkenbeǐn³

2021

Preprint

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Applying the strong pinning formalism to the mixed state of a type II superconductor, we study the effect of thermal fluctuations (or creep) on the penetration of an ac magnetic field as quantified by the so-called Campbell length λC. Within strong pinning theory, vortices get pinned by individual defects, with the jumps in the pinning energy (∆epin) and force (∆fpin) between bistable pinned and free states quantifying the pinning process. We find that the evolution of the Campbell length λC(t) as a function of time t is the result of two competing effects, the change in the force jumps ∆fpin(t) and a change in the trapping area Strap(t) of vortices; the latter describes the area around the defect where a nearby vortex gets and remains trapped. Contrary to naive expectation, we find that during the decay of the critical state in a zero-field cooled (ZFC) experiment, the Campbell length λC(t) is usually nonmonotonic, first decreasing with time t and then increasing for long waiting times. Field cooled (FC) experiments exhibit hysteretic effects in λC; relaxation then turns out to be predominantly monotonic, but its magnitude and direction depends on the specific phase of the cooling-heating cycle. Furthermore, when approaching equilibrium, the Campbell length relaxes to a finite value, different from the persistent current which vanishes at long waiting times t, e.g., above the irreversibility line. Finally, measuring the Campbell length λC(t) for different states, zero-field cooled, field cooled, and relaxed, as a function of different waiting times t and temperatures T , allows to 'spectroscopyse' the pinning potential of the defects.

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Experimental test of strong pinning and creep in current-voltage characteristics of type-II superconductors

Cited by 11 publications

References 28 publications

Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics

Perspective: Challenges and Transformative Opportunities in Superconductor Vortex Physics

Noise signal as input data in self-organized neural networks

Creep effects on the Campbell response in type II superconductors

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