Possible electronic shell structure of nanoscale superconductors

✍ Scribed by K. Tanaka; F. Marsiglio

• Book ID: 104338015
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 156 KB
• Volume: 265
• Category: Article
• ISSN: 0375-9601
• DOI: 10.1016/s0375-9601(99)00854-3

✦ Synopsis

Motivated by recent experiments on Al nanoparticles, we have studied the effects of fixed electron number and small size in nanoscale superconductors, by applying the canonical BCS theory for the attractive Hubbard model in two and three dimensions. As observed in the experiments, a negative 'gap' in particles with an odd number of electrons emerges naturally in the canonical scheme. For particles with an even number of electrons, the canonical energy gap exhibits shell structure as a function of electron density or system size in the weak-coupling regime: the gap is particularly large for 'magic numbers' of electrons for a given system size or of atoms for a fixed electron density. The grand canonical BCS method essentially misses this feature. Possible experimental methods for observing such shell effects are discussed.