The range of giant flux instabilities in the plane in hard superconductors: calculations and experiment

Abstract

We have studied magnetothermal instabilities, giant flux jumps, both theoretically and experimentally. Magnetostriction and magnetization hysteresis loops with flux jumps were calculated over a wide range of experimental parameters employing two critical-state models: the Kim-Anderson model and the exponential model. The influence of the magnetic history on the flux jumps' magnetostriction and magnetization were investigated for the LaSrCuO single crystal. The shape of the unstable region of the critical state in the temperature-magnetic field plane was constructed from calculations and experimental results. In the Kim-Anderson model H-T diagrams of flux instabilities agree well with experimental results on HTSC single-crystal LaSrCuO and experimental results on LTSC niobium.

Coexistence of critical and normal state magnetostrictions in type II superconductors: A model exploration

“…The success achieved by critical state descriptions of a large variety of magnetostriction curves provides strong support for this framework. Exploiting this picture they reproduced all of the features of a family of magnetostriction curves reported by Chabanenko et al 15 Measurements by several workers [23][24][25][26][27] show the presence of a normal state B 2 dependent component in the magnetostriction of type II superconductors near and above H C2 Koziol and Dunlap 28 have examined the effect of such a normal state contribution to the magnetostriction of type II superconductors in the framework of the critical state model. [13][14][15][16][17] Workers have also observed humps at high fields in magnetostriction curves corresponding to the peak or fishtail effect encountered in the magnetization of type II superconductors.…”

“…[13][14][15][16][17] Workers have also observed humps at high fields in magnetostriction curves corresponding to the peak or fishtail effect encountered in the magnetization of type II superconductors. Their work and many subsequent experimental and theoretical investigations 4-28 provide considerable evidence that the compressions and dilatations of the crystal lattice arise from the very strong Lorentz force densities F L = J ϫ B, generated by large excursions of the applied magnetic field H A below the upper critical field H C2 in specimens with strong pinning of the flux lines.…”

The Influence of Magnetic History on the Stability of Critical State and the Dynamics of Flux Jumps in Conventional NbTi Superconductor

“…It is well known that the stability of the critical state depends on the magnetic field distribution in the superconducting sample, and that this distribution is determined by the magnetic history. This problem was already analyzed by Sosnowski [2], Müller and Andrikidis [3] and also in our previous works [4,5]. The influence of the magnetic history on the dynamics of the flux jumps remains poorly understood.…”

Magnetothermal instabilities in type II superconductors

“…The limitation of the number of oscillations observed is caused by the existence of damping. One succeeds in observing the oscillation of the vortex density only owing to a strong compression of the vortex structure as a result of the giant avalanche-flux [17,[24][25][26].…”

“…Chabanenko at al. [24] have studied magnetothermal instabilities and giant flux jumps, both theoretically and experimentally in the framework of adiabatic approximation using various dependencies of the critical current density on the magnetic field. In particular, they have numerically calculated magnetization and magnetostriction loops with flux jumps employing the Kim-Anderson critical state model and exponential model for the dependence jc(H).…”