Nonmonotonic concentration dependence of magnetic response in Fe nanoparticle-polymer composites

Ceylan A. , Baker C., Hasanain S., Shah S.

PHYSICAL REVIEW B, vol.72, no.13, 2005 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 72 Issue: 13
  • Publication Date: 2005
  • Doi Number: 10.1103/physrevb.72.134411
  • Title of Journal : PHYSICAL REVIEW B


We report the magnetic response of composites formed by dispersing Fe nanoparticles in a polymer. Transmission electron microscopy reveals the formation of chain-like entities of nanoparticles. The magnetic response (hysteresis, remanence ratio, exchange bias, etc.) is in general nonmonotonic as a function of the particle concentration in the composites. The coercivity and remanence go through a maximum, while the exchange bias and magnetic relaxation rates go through a minimum, with increasing concentration. The effects are interpreted as being a consequence of a competition between an increasing anisotropy due to the formation of the chain-like entities that tends to increase the remanence, etc., and the weakening of these effects at higher concentrations due to the interactions between these entities.