Magnetic anisotropy in carbon encapsulated Co/CoO “lines” with large exchange bias
2003; Elsevier BV; Volume: 307; Issue: 1 Linguagem: Inglês
10.1016/s0375-9601(02)01678-x
ISSN1873-2429
AutoresHong Bi, Shandong Li, Xiqun Jiang, Youwei Du, Changzheng Yang,
Tópico(s)Magnetic and transport properties of perovskites and related materials
ResumoAbstract Carbon encapsulated cobalt nanoparticles were prepared by Co(II) reduction and post-annealing in inert argon gas. Cobalt nanoparticles form parallel “lines” with approximately equal space of 35 μm on the single-crystal silica substrate in the presence of a magnetic field of 3 kGs. Magnetic measurement results indicate that this system exhibits a strong magnetic anisotropy. Along the line direction, it was ferromagnetic with coercive force of 85 Oe, while perpendicular to the substrate plane, only a narrow hysteresis loop was observed. The samples were oxidized at 573 K for various times under air atmosphere. Coercivity was enhanced due to the exchange coupling between ferromagnetic Co and antiferromagnetic CoO. Compared with the random dispersed Co/CoO nanoparticles that was prepared under the same annealing and oxidation condition, a larger exchange bias was obtained in the magnetic aligned specimen. The mechanism of coercivity enhancement and larger exchange bias was discussed.
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