Superconductivity and localization of electrons in disordered two-dimensional metal systems

Effect of ?-Irradiation on Superconductivity in Polycrystalline YBa2Cu3O7-?

“…The relative contribution of each of these mechanisms depends on the degree of inhomogeneity of the superconducting system [2]. Therefore, although the nature of superconducting paired state in the HTSCs is still obscure, it can be assumed that some features of the disorder influence should be common for both types of superconductors.…”

Hysteresis and stepwise structure in MR curves of granular superconducting ruthenocuprates RuSr2(Gd1.5Ce0.5)Cu2O10−δ

“…It consists of (1) Josephson medium which presents weak links for intergranular propagation of superconducting electrons, and (2) nonsuperconducting (normal) medium through which only transfer of unpaired quasi-particle excitations is possible. A somewhat similar concept has been applied previously for low-T c granular superconductors [24] where resistive transitions were explained by concurrent tunnelling of unpaired quasi-particle excitations and intergrain Josephson tunnelling of Cooper pairs. The intergranular medium is a typical two-component system for which, as has been mentioned above, crossing point effects can appear [23].…”

“…First, negative MR in the low-field range, and, second, saturation of resistance at high enough field when temperature is fairly close to T c0 = 34 K. Above T cJ intergrain Josephson coupling is nearly suppressed so that intergrain conductivity is determined mainly by single-particle tunneling. In this case negative MR appears [24]. It is associated with the reduction of the intragrain superconducting gap ∆(T ) in an applied magnetic field, that causes an increase in the unpaired quasi-particle density and corresponding decrease in resistance [24].…”

“…In this case negative MR appears [24]. It is associated with the reduction of the intragrain superconducting gap ∆(T ) in an applied magnetic field, that causes an increase in the unpaired quasi-particle density and corresponding decrease in resistance [24]. Although the intragrain upper critical field is found to be very large in the Ru1222-Gd compound [10], close enough to T c0 , the field applied in this study (up to 1.6 T) is quite enough to suppress intragrain superconductivity.…”

Large magnetoresistance of insulating silicon films with superconducting nanoprecipitates

“…21,24,25,[60][61][62] Below the critical temperature T c Cooper pairs are formed in the Garich nanoprecipitates which remain localized if the distance between neighboring superconducting regions is too large or the Coulomb barrier too high for tunneling. Otherwise Cooper-pair tunneling and the proximity effect can lead to bigger superconducting clusters that reduce the film resistance.…”