Single-Domain Fe2CoAl Nanoparticles and Their Crystallite Size-Dependent Properties

Abstract

Single-domain Fe2CoAl nanoparticles exhibiting an X-type ordered Heusler alloy structure have been prepared by a simple template-less chemical process. Near-stoichiometric Fe2CoAl nanoparticles with three different average crystallite sizes of 41, 45, and 51 nm exhibit soft ferromagnetic behavior with high saturation magnetization (>95% of the theoretical estimate), high effective magnetic anisotropy (∼107 erg/cc), and a high Curie temperature (∼1225 K). The property variation of the nanoparticles with crystallite size has been explained using well-established theoretical models. Ab initio calculations performed in this study, apart from establishing the preferred crystal structure, also help to understand the magnetic and half-metallic properties of the alloy. Critical size estimations authenticate the formation of single-domain Fe2CoAl nanoparticles.