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Flux noise in high-temperature superconductors

Carsten Timm

DOI 10.1103/PhysRevB.55.3241 · Physical Review B

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Abstract

Spontaneously created vortex-antivortex pairs are the predominant source of flux noise in high-temperature superconductors. In principle, flux noise measurements allow to check theoretical predictions for both the distribution of vortex-pair sizes and for the vortex diffusivity. In this paper the flux-noise power spectrum is calculated for the highly anisotropic high-temperature superconductor Bi2Sr2CaCu2O8+δ, both for bulk crystals and for ultrathin films. The spectrum is basically given by the Fourier transform of the temporal magnetic-field correlation function. We start from a Berezinskii-Kosterlitz-Thouless-type theory and incorporate vortex diffusion, intrapair vortex interaction, and annihilation of pairs by means of a Fokker-Planck equation to determine the noise spectrum below and above the superconducting transition temperature. We find white noise at low frequencies ω and a spectrum proportional to 1/ω3/2 at high frequencies. The crossover frequency between these regimes strongly depends on temperature. The results are compared with earlier results of computer simulations.

Source-reported materials — not catalogue approval

FormulaReported Tc (K)Pressure (GPa)Type
Bi2Sr2CaCu2O8+δ

Archive — visibility unverified

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—Pressure not reportedunknown
Bi2Sr2CaCu2O8

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

—Pressure not reportedunknown
YBa2Cu3O6

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Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.

—Pressure not reportedunknown

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