Parity-fluctuation induced enlargement of the ratio ΔE/kBTV꜀ in metallic grains

Titelangaben

Croitoru, Mikhail D. ; Shanenko, A. A. ; Peeters, F. M. ; Axt, Vollrath Martin:
Parity-fluctuation induced enlargement of the ratio ΔE/kBTV꜀ in metallic grains.
In: Physical Review B. Bd. 84 (2011) Heft 21 . - 214518.
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.84.214518

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Abstract

We investigate how the interplay of quantum confinement and particle number-parity fluctuations affects superconducting correlations in ultra-small metallic grains. Using the number-parity projected BCS formalism we calculate the critical temperature and the excitation gap as a function of the grain size for grains with even and odd number of confined carriers. We show that the experimentally observed anomalous increase of the coupling ratio ΔE/kBTc with decreasing superconducting grain size can be attributed to an enhancement of the number-parity fluctuations in ultra-small grains.