Tunneling Magnetoresistance with Sign Inversion in Junctions Based on Iron Oxide Nanocrystal Superlattices

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 tunne...

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Bibliographic Details
Published in:ACS nano 2011-03, Vol.5 (3), p.1731-1738
Main Authors: Lekshmi, Indira Chaitanya, Buonsanti, Raffaella, Nobile, Concetta, Rinaldi, Ross, Cozzoli, Pantaleo Davide, Maruccio, Giuseppe
Format: Article
Language:English
Subjects:
Electric Impedance
Ferric Compounds - chemistry
Magnetics
Materials Testing
Nanostructures - chemistry
Nanostructures - ultrastructure
Particle Size
Semiconductors
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Summary: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.
ISSN:1936-0851
1936-086X
DOI:10.1021/nn102301y