TY  - JOUR
AU  - Zhang, G.
AU  - Zhang, Y.
AU  - Dong, H.
AU  - Krause, H.-J.
AU  - Xie, X.
AU  - Braginski, A.I.
AU  - Offenhäusser, A.
AU  - Jiang, M.
TI  - Parameter tolerance of the SQUID Bootstrap Circuit
JO  - Superconductor science and technology
VL  - 24
SN  - 0953-2048
CY  - Bristol
PB  - IOP Publ.
M1  - PreJuSER-18096
SP  - 015006
PY  - 2012
N1  - The Istituto Superiore Mario Boella is gratefully acknowledged for financial support.
AB  - The effect of disorder is investigated in granular superconductive materials with strong-and weak-links. The transition is controlled by the interplay of the tunneling g and intragrain g(intr) conductances, which depend on the strength of the intergrain coupling. For g << g(intr), the transition first involves the grain boundary, while for g similar to g(intr) the transition occurs into the whole grain. The different intergrain couplings are considered by modeling the superconducting material as a disordered network of Josephson junctions. Numerical simulations show that on increasing the disorder, the resistive transition occurs for lower temperatures and the curve broadens. These features are enhanced in disordered superconductors with strong-links. The different behavior is further checked by estimating the average network resistance for weak-and strong-links in the framework of the effective medium approximation theory. These results may shed light on long standing puzzles such as: (i) enhancement of the superconducting transition temperature of many metals in the granular states; (ii) suppression of superconductivity in homogeneously disordered films compared to standard granular systems close to the metal-insulator transition; (iii) enhanced degradation of superconductivity by doping and impurities in strongly linked materials, such as magnesium diboride, compared to weakly linked superconductors, such as cuprates.
KW  - J (WoSType)
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000285344400007
DO  - DOI:10.1088/0953-2048/24/1/015006
UR  - https://juser.fz-juelich.de/record/18096
ER  -