1210.2851 (H. Bary-Soroker et al.)

Scale-dependent competing interactions: sign reversal of the average
persistent current    [PDF]

H. Bary-Soroker, O. Entin-Wohlman, Y. Imry, A. Aharony

The interaction-induced orbital magnetic response of a nanoscale system, modeled by the persistent current in a ring geometry, is evaluated for a system which is a superconductor in the bulk. The interplay of the renormalized Coulomb and Fr\"{o}hlich interactions is crucial. The diamagnetic response of the large superconductor may become paramagnetic when the finite-size-determined Thouless energy is larger than or on the order of the Debye energy.

View original: http://arxiv.org/abs/1210.2851