Title :
Experimental study of Hopkinson effect in single domain CoFe2 O4 particles
Author :
Gajbhiye, N.S. ; Prasad, Seema ; Blaji, G.
Author_Institution :
Dept. of Chem., Indian Inst. of Technol., Kanpur, India
fDate :
7/1/1999 12:00:00 AM
Abstract :
Nanosize particles of CoFe2O4 have been synthesized by the citrate precursor technique. Considerably higher coercive force (1.68 kOe) than that obtained by the conventional technique (1.00 kOe) is associated with the nanostructure of CoFe2 O4. These nanosize ferrimagnetic CoFe2O4 particles exhibit chainlike clusters indicating strong interparticle interactions and reduced magnetic moment, which is attributed to anisotropy and canted spin structure at the surface of the particle. The magnetization shows a peak just below the Curie temperature Tc during heating in the presence of a small magnetic field (the Hopkinson effect), On the other hand, the magnetization increases monotonically when the system is cooled from T c. This peak is associated with the single domain behavior of nanocrystalline CoFe2O4 particles and explained within the mathematical formalism given by Stoner and Wohlfarth in conjunction with other explanations of Hopkinson effect
Keywords :
Curie temperature; canted spin arrangements; cobalt compounds; ferrites; magnetic anisotropy; magnetic domains; magnetic moments; magnetic particles; nanostructured materials; CoFe2O4; Curie temperature; Hopkinson effect; anisotropy; canted spin structure; chainlike clusters; citrate precursor technique; coercive force; magnetization; nanocrystalline CoFe2O4 particles; nanosize ferrimagnetic CoFe2O4 particles; nanosize particles; nanostructure; reduced magnetic moment; single domain CoFe2O4 particles; single domain behavior; strong interparticle interactions; Amorphous magnetic materials; Coercive force; Ferrites; Heating; Iron; Magnetic domain walls; Magnetic domains; Neodymium; Saturation magnetization; Temperature;
Journal_Title :
Magnetics, IEEE Transactions on
