Magnetothermal properties of Nb-W, Nb-Ti, and Nb-Mo alloys in the mixed state

Abstract

Flux jumps and magnetothermal effects in single crystals of niobium and niobium doped with tungsten, titanium, and molybdenum have been studied in the mixed state in a vacuum calorimeter. It is observed that (a) the field at which the first flux jump occurs is independent of the sweep rate at low sweep rates (1-10 Oe sec) but increases sharply at higher sweep rates (~100 Oe/sec) of the magnetic field, (b) the heat evolved during the flux jump becomes larger as the sample's temperature is reduced, (c) the temperature fluctuations of the type observed by Zebouni et al. and Levy et al. are evidently due to the imperfect adiabatic conditions of experiments, and (d) the interval between the successive flux jumps is in good agreement with that expected from the critical state model of Swartz and Bean.