title: Magnetoresistance of drop-cast film of cobalt-substituted magnetite nanocrystals.
abstract: An oleic acid-coated Fe2.7Co0.3O4 nanocrystal (NC) self-assembled film was fabricated via drop casting of colloidal particles onto a three-terminal electrode/MgO substrate. The film exhibited a large coercivity (1620 Oe) and bifurcation of the zero-field-cooled and field-cooled magnetizations at 300 K. At 10 K, the film exhibited both a Coulomb blockade due to single electron charging as well as a magnetoresistance of ∼-80% due to spin-dependent electron tunneling. At 300 K, the film also showed a magnetoresistance of ∼-80% due to hopping of spin-polarized electrons. Enhanced magnetic coupling between adjacent NCs and the large coercivity resulted in a large spin-polarized current flow even at 300 K.
authors.affiliation: Department of Materials Science, Kyushu Institute of Technology , 1-1 Sensui, Tobata, Kitakyushu, Fukuoka 804-8550, Japan.
authors.forename: Shigemi
authors.initials: S
authors.lastname: Kohiki
authors.forename: Koichiro
authors.initials: K
authors.lastname: Nara
authors.forename: Masanori
authors.initials: M
authors.lastname: Mitome
authors.forename: Daiju
authors.initials: D
authors.lastname: Tsuya
keywords: Coulomb blockade; cobalt-substituted magnetite nanocrystal; coercivity; spin-polarized current; tunnel magnetoresistance