Vortex avalanches in a Pb-porous glass nanocomposite

Abstract

Magnetic properties of a superconducting lead-porous glass composite were studied. The glass pore size was 7 nm. The onset of superconductivity was observed at 7.22 K with complete diamagnetic screening at lower temperatures. Strong magnetic instabilities were found on the magnetization-versus-field loops in the temperature range from 1.8 to 5.5 K at a sweep rate of 20 Oe/s. The shape of the hysteresis loops above 2.5 K was typical for other types of hard type-II superconductors in the adiabatic limit, the field of the first jump on the virgin magnetization being maximal at 3.5 K. Below 2.5 K the hysteresis loops become complex, showing different behavior at lower and higher fields. The nature of such a loop was discussed. The smooth hysteresis loops just below the superconducting transition had fishtails that completely disappeared down to 6 K. The evolution of magnetization instabilities until complete smoothing away the hysteresis loops with increasing or decreasing the sweep rate was observed at 1.8 or 5 K, respectively.

A radio-frequency coil for the microwave characterization of vortex dynamics in thin film superconductors

“…This interface rushes deep into the sample in an attempt to establish the lowest-energy state, for which the flux distribution should be smooth everywhere. TMI has been reported as a sudden penetration of the flux front forming vortex avalanches, 68 intermittent dendritic pattern of flux channels, 69 flux jumps, 70 or vortex microavalanches 71 in Pb composites. Moreover, nano-scaled defects, which enhance the critical current density and the Joule heating, have proven to favor the development of vortex instabilities in the form of quasi-one-dimensional micro-jumps in nano-granular samples of NbN due to the rise of the local electrical fields.…”

Размерные Зависимости Магнитных Свойств Сверхпроводящих Наноструктур Свинца В Пористом Стекле

“…Также в них наблюдается рост значений критического магнитного поля СП-перехода (H c ≤ 2 T при T = 0 K) и критической температуры (T c ≤ 4.5 K) по сравнению со значениями для массивного ин-дия (T c = 3.4 K, H c (0) = 280 Oe). Аналогичные эффекты изучались также в различных структурах на основе In [2,3] и Pb [4,5]. Отметим, что для массивного свин-ца T c = 7.2 K, и заметного роста T c в структурах на основе свинца, как правило, не наблюдалось.…”

“…Зависимость магнитного момента от магнитного поля M(H) характеризуется большим гистерезисом и наличием скачков M в зави-симости от внешнего магнитного поля при T < T c [5,6].…”

SANS studies of nanostructured low-melting metals at room temperature

“…Confinement changes the phonon spectra of metal nanoparticles [5][6][7][8][9][10] and the properties of their electron subsystems [11][12][13][14]. The most surprising changes have been observed for the superconducting properties of gallium, indium, lead and tin [15][16][17][18][19][20] nanoparticles obtained by introducing these metals into nanoporous alkali borosilicate glasses. Furthermore, for this type of porous glass, we will use the abbreviation PG.…”