title: Tunneling magnetoresistance with sign inversion in junctions based on iron oxide nanocrystal superlattices.
abstract: Magnetic tunnel junctions sandwiching a superlattice thin film of iron oxide nanocrystals (NCs) have been investigated. The transport was found to be controlled by Coulomb blockade and single-electron tunneling, already at room temperature. A good correlation was identified to hold between the tunnel magnetoresistance (TMR), the expected magnetic properties of the NC arrays, the charging energies evaluated from current-voltage curves, and the temperature dependence of the junction resistance. Notably, for the first time, a switching from negative to positive TMR was observed across the Verwey transition, with a strong enhancement of TMR at low temperatures.
authors.affiliation: NNL CNR-Istituto Nanoscienze, Via per Arnesano, 73100 Lecce, Italy.
authors.forename: Indira Chaitanya
authors.initials: IC
authors.lastname: Lekshmi
authors.forename: Raffaella
authors.initials: R
authors.lastname: Buonsanti
authors.forename: Concetta
authors.initials: C
authors.lastname: Nobile
authors.forename: Ross
authors.initials: R
authors.lastname: Rinaldi
authors.forename: Pantaleo Davide
authors.initials: PD
authors.lastname: Cozzoli
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Maruccio
mesh_terms: D017097:Electric Impedance; D005290:Ferric Compounds / Q000737:chemistry*; D008280:Magnetics; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012666:Semiconductors
chemical_list: D005290:Ferric Compounds; C000499:ferric oxide