1. Fabrication and enhanced magnetoresistance of SiO2-coated Fe3O4 nanosphere compact.
- Author
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Wang, Junfeng, Shi, Jing, Tian, Decheng, Deng, Hong, Li, Yadong, Song, Pengyun, and Chen, Chinping
- Subjects
MAGNETIC fields ,CRYSTAL grain boundaries ,ELECTRIC resistance ,SINTERING ,IRON oxides ,NANOSTRUCTURED materials - Abstract
Magnetoresistance (MR) of a nanostructured material, monodisperse Fe
3 O4 nanospheres of about 200 nm coated with thin SiO2 and compactly cold pressed and sintered, has been investigated. A high MR, up to 10.8% at 1 T and 17% at 8 T, has been observed at 100 K. This enhanced MR is likely arising from the spin-polarized tunneling of conducting electrons through the insulating SiO2 boundaries. The decrease of the MR with the temperature increasing was attributed to the existence of the local spins in the grain boundaries. In addition, the MR ratio decreases with the SiO2 thickness increasing and sintering temperature decreasing. It suggests that the magnetic property of the insulating barrier is crucial for enhancing the low-field MR at a high temperature. [ABSTRACT FROM AUTHOR]- Published
- 2007
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