Tailoring magnetic properties of core/shell nanoparticles

©2004 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: http://link.aip.org/link/?APPLAB/85/792/1DOI:10.1063/1.1776632Bimagnetic FePt/MFe₂O₄ sM=Fe,Cod core/shell nanoparticles are synthesized via high-temperature solution phase coating of 3.5 nm FePt core with MFe₂O₄ shell. The thickness of the shell is controlled from 0.5 to 3 nm. An assembly of the core/shell nanoparticles shows a smooth magnetization transition under an external field, indicating effective exchange coupling between the FePt core and the oxide shell. The coercivity of the FePt/Fe₃O₄ particles depends on the volume ratio of the hard and soft phases, consistent with previous theoretical predictions. These bimagnetic core/shell nanoparticles represent a class of nanostructured magnetic materials with their properties tunable by varying the chemical composition and thickness of the coating materials