Abstract
Poly(vinyl pyrrolidone)/CoFe2O4 nanocomposite has been fabricated by a sol-gel auto-combustion method. Poly(vinyl pyrrolidone) was used as a reducing agent as well as a surface capping agent to prevent particle aggregation and stabilize the particles. The average crystallite size estimated from X-ray line profile fitting was found to be 20 +/- 7 nm. The high field irreversibility and unsaturated magnetization behaviours indicate the presence of the core-shell structure in the sample. The exchange bias effect observed at 10 K suggests the existence of the magnetically aligned core surrounded by spin-disordered surface layer. The reduced remanent magnetization value of 0.6 at 10 K (higher than the theoretical value of 0.5) shows the PVP/CoFe2O4 nanocomposite to have cubic magnetocrystalline anisotropy according to the Stoner-Wohlfarth model. (C) 2013 Elsevier Ltd. All rights reserved.