Resistive States of Hard Superconductors

Abstract

In summary, the general qualitative ideas of flux creep theory appear to be soundly based and to allow for the qualitative and semiquantitative understanding of a wide range of phenomena. Many problems remain, both for detailed quantitative study and even for better qualitative understanding. To list a few of these:(1) More detailed understanding of flux line interactions, in particular a sounder basis for the "bundle" concept and an understanding of Bs and of the pea, k eHect.(2) The peculiar transient pulses observed by Kim et at. s These support the creep idea qualitatively, but are too large to be individual lines or bundles and too small to be instabilities. Are they avalanches'(3) The nonlinear diffusion equation: when is it unstable'(4) The viscous state. This is a completely new theoretical problem and I know of no obvious way even of approaching it from fundamental theory.

Voltage-biased superconducting transition-edge bolometer with strong electrothermal feedback operated at 370 mK

“…Excess noise is seen for frequencies less than 0.6 Hz, which has a frequency dependence close to 1͞f for all values of R. Possible candidates include microphonics from the suspension and the electrical wires, resistivity fluctuations of the superconducting Ti film, 9 and superconducting flux motion. 10 We examined the effect of microphonics by mounting an electromagnetic driver on the cryostat, which was driven from a white-noise source at several power levels. It was found that the threshold for increasing the noise at low frequencies with the driver was very low.…”

“…Excess noise for a VSB may have contributions from various sources, such as fluctuations in T 0 , microphonics, contact shot noise, 8 resistivity fluctuations, 9 and superconducting flux noise. 10 For direct comparison with measurements, it is useful to rewrite the noise of a VSB in terms of noise current referred to the input of the SQUID,…”

Critical State Theory for Nonparallel Flux Line Lattices in Type-II Superconductors

“…By virtue of the symmetry, we can restrict to the interval 0 ≤ x ≤ a. Along this work, we will use a Kim's model type [11] dependence of the critical current density …”

Direct observation of quantized interlayer vortex flow in a high-Tc La1.87Sr0.13CuO4 single crystal

“…The direction of vortex flow is perpendicular to the current direction. A number of measurements on flux flow resistivity [1][2][3] and application to flux flow devices [4][5][6] have been reported. In anisotropic high-T c cuprate superconductors, the flow phenomenon of interlayer vortices induced by a transport current led to novel concept of Josephson plasma terahertz emission [7,8].…”

“…where v L is the vortex velocity, η  is the viscosity coefficient of medium, f P is the pinning force and f L is the Lorentz force given by f L = J T Φ 0 /c (J T : transport current density) [1][2][3]. The direction of vortex flow is perpendicular to the current direction.…”