title: Enhanced spin accumulation and novel magnetotransport in nanoparticles.
abstract: Spin injection and accumulation are key phenomena supporting a variety of concepts for spin-electronic devices. These phenomena are expected to be enhanced in nanoparticles over bulk structures due to their discrete energy levels and large charging energies. In this article, precise magnetotransport measurements in the single-electron tunnelling regime are performed by preparing appropriate microfabricated devices containing cobalt nanoparticles. Here we provide experimental evidence for characteristic features of spin accumulation in magnetic nanoparticles, such as oscillations of the magnetoresistance with a periodical sign change as a function of bias voltage. Theoretical analysis of the magnetoresistance behaviour clearly shows that the spin-relaxation time in nanoparticles is highly enhanced in comparison with that in the bulk.
authors.affiliation: Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan. kyaku@imr.tohoku.ac.jp
authors.forename: Kay
authors.initials: K
authors.lastname: Yakushiji
authors.forename: Franck
authors.initials: F
authors.lastname: Ernult
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imamura
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Yamane
authors.forename: Seiji
authors.initials: S
authors.lastname: Mitani
authors.forename: Koki
authors.initials: K
authors.lastname: Takanashi
authors.forename: Saburo
authors.initials: S
authors.lastname: Takahashi
authors.forename: Sadamichi
authors.initials: S
authors.lastname: Maekawa
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Fujimori
mesh_terms: D003035:Cobalt; D004583:Electrons; D008280:Magnetics; D008962:Models, Theoretical; D049329:Nanostructures
chemical_list: D003035:Cobalt