Size-controlled Synthesis and Magnetic Properties of FePt/PbS Core/Shell Nanoparticles

Abstract

A method to prepare FePt/PbS core/shell nanoparticles with a controllable PbS thickness (dPbS) based on the reaction of lead oleate and sulfur in the presence of FePt nanoparticles has been developed. It was demonstrated that dPbS can be finely controlled from ca. 0.5 to 4.3 nm by adjusting the reaction temperature and/or the time. The resulting FePt/PbS core/shell nanoparticles with various dPbS’s showed smaller magnetic anisotropies than those of the pristine FePt nanoparticles. The observed anisotropies were almost constant and independent of dPbS. This result indicates that it is the surface anisotropy and not the interparticle magnetic dipolar interactions that predominantly determines the magnetic properties of the FePt/PbS core/shell nanoparticles.