title: Enhanced room temperature magnetoresistance and spin injection from metallic cobalt in Co/ZnO and Co/ZnAlO films.
abstract: Co/ZnO and Co/ZnAlO films were prepared by depositing ultrathin cobalt layers and semiconductor layers on glass substrates at room temperature. The films consist of metallic Co particles, semiconductor matrix, and an interfacial magnetic semiconductor with the substitution of Co(2+) for Zn(2+) in the ZnO lattice at the interface between Co particles and the semiconductor matrix. Large room temperature negative tunneling magnetoresistance was observed in the films. In addition, the magnetism and magnetoresistance were obviously enhanced by adding aluminum to the ZnO, and in one Co/ZnAlO sample, the room temperature negative magnetoresistance value reaches -12.3% at 18 kOe (compared with -8.4% of the corresponding Co/ZnO film) and the spin polarization of the tunneling electrons is about 37.5% which is characteristic of metallic Co. This enhancement of the tunneling spin polarization has been ascribed to the tunneling through an interfacial magnetic semiconductor, which causes the robust spin injection from cobalt metal into the semiconductors at room temperature resulting from the spin filter effect of the interfacial magnetic semiconductors.
authors.affiliation: Key Laboratory of Magnetic Molecules and Magnetic Information Materials of Ministry of Education and School of Chemistry and Materials Science, Shanxi Normal University, Linfen 041004, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Quan
authors.forename: Xianpeng
authors.initials: X
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Li
authors.forename: Kiri
authors.initials: K
authors.lastname: Addison
authors.forename: Gillian A
authors.initials: GA
authors.lastname: Gehring
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Xu