Ultra-small metallic grains: effect of statistical fluctuations of the chemical potential on superconducting correlations and vice versa.
Superconducting correlations in an isolated metallic grain are governed by the interplay between two energy scales: the mean level spacing δ and the bulk pairing gap Δ0, which are strongly influenced by the position of the chemical potential with respect to the closest single-electron level. In turn superconducting correlations affect the position of the chemical potential. Within the parity projected BCS model we investigate the probability distribution of the chemical potential in a superconducting grain with randomly distributed single-electron levels. Taking into account statistical fluctuations of the chemical potential due to the pairing interaction, we find that such fluctuations have a significant impact on the critical level spacing δc at which the superconducting correlations cease: the critical ratio δc/Δ0 at which superconductivity disappears is found to be increased.
LOMA, Université Bordeaux I, UMR 5798, F-33400 Talence, France. mihail.croitoru@u-bordeaux1.fr
M D
MD
Croitoru
A A
AA
Shanenko
C C
CC
Kaun
F M
FM
Peeters
D004553:Electric Conductivity; D004583:Electrons; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D015233:Models, Statistical; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011789:Quantum Theory
D008670:Metals