title: Long spin lifetime and large barrier polarisation in single electron transport through a CoFe nanoparticle.
abstract: We have investigated single electron spin transport in individual single crystal bcc Co30Fe70 nanoparticles using scanning tunnelling microscopy with a standard tungsten tip. Particles were deposited using a gas-aggregation nanoparticle source and individually addressed as asymmetric double tunnel junctions with both a vacuum and a MgO tunnel barrier. Spectroscopy measurements on the particles show a Coulomb staircase that is correlated with the measured particle size. Field emission tunnelling effects are incorporated into standard single electron theory to model the data. This formalism allows spin-dependent parameters to be determined even though the tip is not spin-polarised. The barrier spin polarisation is very high, in excess of 84%. By variation of the resistance, several orders of magnitude of the system timescale are probed, enabling us to determine the spin relaxation time on the island. It is found to be close to 10 μs, a value much longer than previously reported.
authors.affiliation: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: R C
authors.initials: RC
authors.lastname: Temple
authors.affiliation: Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: M
authors.initials: M
authors.lastname: McLaren
authors.affiliation: Institute for Materials Research, School of Chemical and Process Engineering, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: R M D
authors.initials: RM
authors.lastname: Brydson
authors.affiliation: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: B J
authors.initials: BJ
authors.lastname: Hickey
authors.affiliation: School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: Marrows