title: Magnetoresistance and microstructure of magnetite nanocrystals dispersed in indium-tin oxide thin films.
abstract: Epitaxial indium-tin oxide (ITO) thin films were fabricated on a yttria-stabilized zirconia (YSZ) substrate by pulsed-laser deposition using magnetite (Fe(3)O(4)) nanoparticle dispersed ITO powders as a target. Magnetoresistance of the film at a field of 1 T was 39% at 45 K, and it stayed at 3% above 225 K. The film demonstrated cooling hysteresis in the temperature dependence of direct-current magnetization. Transmission electron microscopy revealed that phase-separated Fe(3)O(4) nanocrystals with widths of approximately 40-150 nm and heights of approximately 10-25 nm precipitated and grew epitaxially on the substrate in the film. Both the Fe(3)O(4)(111) and ITO(001) planes were parallel to the YSZ(001) plane. The Fe(3)O(4)(11-2) and -(1-10) planes were parallel to the ITO(100) and -(010) planes, respectively, and the planes connected smoothly at the grain boundary. The contour map of the electron density for the Fe(3)O(4)(111) plane by the first-principles electronic structure computation was similar to that for the ITO(001) plane. The [111]-oriented Fe(3)O(4) nanocrystals played the role of spin aligner for charge carriers of the epitaxial ITO film.
authors.affiliation: Departments of Materials Science and of Basic Science, Kyushu Institute of Technology, 1-1 Sensui, Tobata, Kitakyushu 804-8550, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Okada
authors.forename: Shigemi
authors.initials: S
authors.lastname: Kohiki
authors.forename: Masanori
authors.initials: M
authors.lastname: Mitome
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Tanaka
authors.forename: Masao
authors.initials: M
authors.lastname: Arai
authors.forename: Masaki
authors.initials: M
authors.lastname: Mito
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Deguchi