Dispersible and manipulable magnetic L10-FePt nanoparticles

Abstract

Oriented single-domain magnetic nanoparticles with a high remanence ratio M_r/M_s and maximum magnetic energy product (BH)_max have attracted immense attention. However, nanoparticles easily agglomerate due to their extremely small size, which impedes the process of orientation. So manipulating the orientation of nanoparticles is still a key challenge. Here, L1₀-FePt single-domain nanoparticles were successfully synthesized by a chemical method in the liquid phase and nanoparticle-based anisotropic nanocomposites were obtained by dispersing the nanoparticles in liquid epoxy resin under an external magnetic field. The main factors that impact the orientation of L1₀-FePt single-domain nanoparticles were investigated further. It is found that the dispersibility of nanoparticles has a great impact on the degree of orientation, so do the applied magnetic field and the concentration of nanoparticles. Nanocomposites with homodisperse nanoparticles oriented under a suitable external magnetic field exhibit excellent magnetic performance, such as high coercivity H_c and remanence M_r, which gives the nanocomposites a higher (BH)_max than the isotropic samples. The anisotropic nanocomposites show great potential in multifarious permanent magnet applications and fundamental research.