Simulation of vortex noise in superconductors in weak applied magnetic fields

Vestergren, Anders; Wallin, Mats

doi:10.1103/physrevb.69.144522

Cited by 4 publications

(5 citation statements)

References 17 publications

(38 reference statements)

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“…3.4(c). Similar broadband noise that is associated with incoherent flux transport has been experimentally and numerically observed in a number of studies [29,6,19]. For ρ = 36/A, as the vortices begin to arrange into a lattice a narrowband peak appears corresponding to the x wave vector components that appear in the structure factor plot.…”

Section: Randomly Distributed Columnar Defectssupporting

confidence: 73%

“…These 'rivers' of vortices form at different locations in the sample, and flow around 'islands' of temporarily trapped flux lines resulting in incoherent motion. Such behavior has been observed experimentally [4], as well as in two-dimensional computer simulations [5], and is characterized in the velocity or voltage frequency power spectrum by a broadband noise signal which obeys a 1/ω α power law, as also demonstrated in recent three-dimensional numerical work [6].…”

Section: Introductionsupporting

confidence: 59%

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Vortex washboard voltage noise in type-II superconductors

et al. 2008

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In order to characterize flux flow through disordered type-II superconductors, we investigate the effects of columnar and point defects on the vortex velocity / voltage power spectrum in the driven non-equilibrium steady state. We employ three-dimensional Metropolis Monte Carlo simulations to measure relevant physical observables including the force-velocity / current-voltage (I-V) characteristics, vortex spatial arrangement and structure factor, and mean flux line radius of gyration. Our simulation results compare well to earlier findings and physical intuition. We focus specifically on the voltage noise power spectra in conjunction with the vortex structure factor in the presence of weak columnar and point pinning centers. We investigate the vortex washboard noise peak and associated higher harmonics, and show that the intensity ratios of the washboard harmonics are determined by the strength of the material defects rather than the type of pins present. Through varying columnar defect lengths and pinning strengths as well as magnetic flux density we further explore the effect of the material defects on vortex transport. It is demonstrated that the radius of gyration displays quantitatively unique features that depend characteristically on the type of material defects present in the sample.

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Section: Randomly Distributed Columnar Defectssupporting

confidence: 73%

Section: Introductionsupporting

confidence: 59%

Vortex washboard voltage noise in type-II superconductors

et al. 2008

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“…A power law broadband noise spectrum S(ω) ∼ 1/ω α was also reported in simulations of two-and three-dimensional XY and dual Coulomb gas models [44], where at zero magnetic field an exponent α = 1.5 was found, whereas α ≈ 1 in a system with small applied magnetic field. These results are similar to the experimental data reported in [58,59], where the voltage noise spectrum decays at high frequency like 1/ω at elevated temperature and like 1/ω 3/2 at lower temperature.…”

Section: Figure 16supporting

confidence: 65%

“…The voltage noise spectrum can display broadband or narrowband noise. It has been shown that in the presence of weak point defects, and at low driving force, vortices are in a plastic flow regime, characterized by a broadband noise signal S(ω) ∼ ω −α [44]. This power law may be interpreted as a remnant of the zero-temperature continuous depinning transition.…”

Section: Voltage Noise Spectrummentioning

confidence: 99%

Nonequilibrium steady states of driven magnetic flux lines in disordered type-II superconductors

Klongcheongsan¹,

Bullard²,

Täuber³

2009

Supercond. Sci. Technol.

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Abstract. We investigate driven magnetic flux lines in layered type-II superconductors subject to various configurations of strong point or columnar pinning centers by means of a three-dimensional elastic line model and Metropolis Monte Carlo simulations. We characterize the resulting nonequilibrium steady states by means of the force-velocity / current-voltage curve, static structure factor, mean vortex radius of gyration, number of double-kink and half-loop excitations, and velocity / voltage noise spectrum. We compare the results for the above observables for randomly distributed point and columnar defects, and demonstrate that the three-dimensional flux line structures and their fluctuations lead to a remarkable variety of complex phenomena in the steady-state transport properties of bulk superconductors.

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“…Even though 1/f behavior of noise is ubiquitous in transport measurements of many physical systems, 28 to the best of our knowledge, it has not been measured for the Nernst signal. In YBCO samples, a similar power-law behavior has been observed in flux noise spectra in a nondriven system 29 and in longitudinal-voltage noise spectra in a current-driven system. 30 Although the above measurements have been done for regimes and observables other than those presented here, they illustrate the feasibility of the noise-measurement scenario we propose here.…”

Section: B Noise Analysissupporting

confidence: 65%

Numerical simulation of the Nernst effect in extreme type-II superconductors: A negative Nernst signal and its noise power spectra

2012

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Recently, different transport coefficients have been measured in High-Tc superconductors to pinpoint the nature of the pseudogap phase. In particular, the thermoelectric coefficients received a considerable attention both theoretically and experimentally. We numerically simulate the Nernst effect in extreme type-II superconductors using the time-dependent Ginzburg-Landau equations. We report the sign reversal of the thermoelectric coefficient, αxy, at temperatures close to the mean-field transition temperature, T MF c (H), which qualitatively agrees with recent experiments on high-Tc materials. We also discuss the noise power spectrum of αxy, which shows 1/f β behavior. Based on this observation, we propose an experiment to distinguish among different regimes of vortex dynamics by measuring the noise correlations of the Nernst signal.

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Simulation of vortex noise in superconductors in weak applied magnetic fields

Cited by 4 publications

References 17 publications

Vortex washboard voltage noise in type-II superconductors

Vortex washboard voltage noise in type-II superconductors

Nonequilibrium steady states of driven magnetic flux lines in disordered type-II superconductors

Numerical simulation of the Nernst effect in extreme type-II superconductors: A negative Nernst signal and its noise power spectra

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