Experimental study of Hopkinson effect in single domain CoFe[sub 2]O[sub 4] particles

Journal Article · Thu Jul 01 00:00:00 EDT 1999 · IEEE Transactions on Magnetics

DOI:https://doi.org/10.1109/20.774187· OSTI ID:6434187

Gajbhiye, N S; Prasad, S; Balaji, G ^[1]

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1. Indian Inst. of Tech., Kanpur (India). Dept. of Chemistry

Nanosize particles of CoFe[sub 2]O[sub 4] 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 CoFe[sub 2]O[sub 4]. These nanosize ferrimagnetic CoFe[sub 2]O[sub 4] 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 [Tc]. This peak is associated with the single domain behavior of nanocrystalline CoFe[sub 2]O[sub 4] particles and explained within the mathematical formalism given by Stoner and Wohlfarth in conjunction with other explanations of Hopkinson effect.

• OSTI ID: 6434187
• Journal Information: IEEE Transactions on Magnetics, Vol. 35:4; ISSN 0018-9464
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ANISOTROPY
COBALT OXIDES
COERCIVE FORCE
CURIE POINT
FERRIMAGNETIC MATERIALS
IRON OXIDES
MAGNETIC MOMENTS
MAGNETIZATION
SYNTHESIS
CHALCOGENIDES
COBALT COMPOUNDS
IRON COMPOUNDS
MAGNETIC MATERIALS
MATERIALS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS
TRANSITION TEMPERATURE
360204* - Ceramics
Cermets
& Refractories- Physical Properties