Renormalization of competing interactions and superconductivity on small scales

A. Aharony*, O. Entin-Wohlman, Y. Imry

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The interaction-induced orbital magnetic response of a nanoscale ring is evaluated for a diffusive system which is a superconductor in the bulk. The interplay of the renormalized Coulomb and Fröhlich interactions is crucial. The magnetic susceptibility which results from the fluctuations of the uniform superconducting order parameter is diamagnetic (paramagnetic) when the renormalized combined interaction is attractive (repulsive). Above the transition temperature of the bulk the total magnetic susceptibility has contributions from many wave-vector- and (Matsubara) frequency-dependent order parameter fluctuations. Each of these contributions results from a different renormalization of the relevant coupling energy, when one integrates out the fermionic degrees of freedom. The total diamagnetic response of the large superconductor may become paramagnetic when the system’s size decreases.

Original languageEnglish
Pages (from-to)979-989
Number of pages11
JournalJournal of Statistical Physics
Issue number4-5
StatePublished - 18 Oct 2014


FundersFunder number
United States-Israel Binational Science Foundation
Israel Science Foundation


    • Persistent current
    • Renormalization
    • Size-dependence
    • Superconductivity


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