S. Iwabuchi et al., COULOMB-BLOCKADE AND ENHANCEMENT OF MAGNETORESISTANCE CHANGE IN ULTRASMALL FERROMAGNETIC TUNNEL-JUNCTIONS, Physica. B, Condensed matter, 251, 1998, pp. 276-280
Coulomb blockade and negative magnetoresistance of ultrasmall ferromag
netic tunnel junctions are studied based on the Feynman path integral
approach. It is shown that the change in magnetoresistance is consider
ably enhanced in the Coulomb blockade regime. This is due to the nonli
near current-voltage characteristics caused by the higher-order tunnel
ing processes which set in since negative magnetoresistance tends to m
ake Coulomb blockade unstable. Results obtained are qualitatively in g
ood agreement with recent experimental findings. Coulomb blockade and
the magnetoresistance in ultrasmall ferromagnetic double junction are
also discussed briefly. (C) 1998 Elsevier Science B.V. All rights rese
rved.