Eur. Phys. J. B 54, 309-314 (2006)
https://doi.org/10.1140/epjb/e2006-00453-9

Interplay between exchange interactions and charging effects in metallic grains

¹ Institut für Theoretische Festkörperphysik and DFG-Center for Functional Nanostructures (CFN), Universität Karlsruhe, 76128 Karlsruhe, Germany
² Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid, Spain
³ Department of Physics, University of California at San Diego, La Jolla, California, 92093, USA

Corresponding author: ^a pablo@tfp.uni-karlsruhe.de

Received: 1 June 2006
Revised: 26 October 2006
Published online: 22 December 2006

Abstract

We study the effect of strong antiferromagnetic exchange interactions in metallic grains in the Coulomb blockade regime. These interactions can be large in superconducting systems or in metallic antiferromagnetic particles. We extend the standard description of the grain in terms of a single collective variable, the charge and its conjugated phase, to include the spin degree of freedom. The suppression of spin fluctuations enhances the tendency towards Coulomb blockade. The effective charging energy and conductance are calculated numerically in the regime of large grain-lead coupling.