Interparticle interaction and size effect in polymer coated magnetite nanoparticles

Abstract

Magnetization and Mossbauer studies have been performed on the polymer coated\nmagnetite nanoparticles with particle size from 5.1 to 14.7 nm. The maximum in\nthe temperature dependence of magnetization (TM) is found to be inconsistent\nwith the particle size (DTEM). The effective magnetic anisotropy (Kan) is found\nto increase with the decrease of DTEM, which is attributed to the increase of\nsurface anisotropy. The absence of coercivity and remanence of magnetization\nnoticed well above TM indicates the superparamagnetic behaviour, which has also\nbeen observed in the temperature dependent Mossbauer results. The temperature\ndependence of hyperfine field is found to follow similar dependence of\nsaturation magnetization for bulk magnetite.\n