Magnetothermal Effects in Type II Superconductors

Critical state stability in type-II superconductors and superconducting-normal-metal composites

“…Following the flux jump, the sample cools down to T= T, and, on subsequent increase of the external field, the effect is repeated. A similar pattern of oscillations preceding the instability has been observed experimentally by numerous authors (Zebouni et al , 1964;Shapira, 1964, 1966;Goedemoed et al , 1965;Deloastillo and Gswald, 1968;Chikaba, 1970;Shimamoto, 1974). Deloastillo and Oswald (1968) have demonstrated that in Nb, Sn samples both oscillations and limited flux jumps can occur, depending on the conditions (Fig.…”

“…For example, in one and the same sample flux jumps may occur in the low field region and disappear in high fields. This fact has been observed repeatedly in experiments (see Zebouni et al , 1964). It is worthy of note that flux jumps may again occur at H-H, because of the growth of Sj, /ST~~(1 -H/H, , ) '.…”

“…At the same time, this dependence finds a natural interpretation within the framework of the present theory. The data provided by Zebouni et al (1964) are, unfortunately, insufficient to show which one of the above-discussed approximations is closest to their experimental situation. It is clear, however, that slow oscillations were observed.…”

“…26. Experimentally measured period of oscillations in Nb-Zr (a) and Nb (~) samples as a function of temperature(Zebouni et al , 1964).…”

Vortex avalanches in Nb thin films: Global and local magnetization measurements

“…Regarding measurements of thermomagnetic instabilities in Nb we note that flux jumps at low applied fields accompanied by temperature fluctuations and vanishing of these with increasing field have been reported for a Nb crystal long ago. 11 More recently, Hall probes have been used to measure the internal field and some characteristics of vortex avalanches in a 20 m thick polycrystalline Nb sample. 12 According to these authors the observed catastrophic avalanches at low temperatures cannot be understood within the concept of self-organized critically alone.…”