Effective anisotropy field variation of magnetite nanoparticles with size reduction

摘要: Size effect on the internal magnetic structure has been investigated weakly interacting magnetite (Fe3O4) nanoparticles by ferromagnetic resonance experiments at 9.5 GHz as a function of temperature (4–300 K). A set three samples with mean particle size 2.5 nm, 5.0 nm and 13.0 respectively, were prepared chemical route narrow distribution (σ < 0.27). To minimize dipolar interaction, particles dispersed in liquid solid polymer matrix ∼0.6% mass. By freezing suspension an applied external field, textured was obtained. Thus, both random suspensions studied compared. The zero-field-cooled field-cooled conditions carried out to study effective anisotropy field. dc magnetization measurements clearly show that strongly affected size.