Low-loss multiferroic Fe3O4/BaTiO3 core/shell nanoparticles

초록

To overcome the hindrance of possible application of multiferroics in nano-scale, we have investigated the magnetoelectric coupling in ferroelectric and ferromagnetic composites, with a very special geometry, i.e., core/shell nanoparticles. The nanoparticles are consisted of highly-insulating ferroelectric BaTiO3 as a shell with a 50 nm thickness and semi-conducting ferrimagnetic Fe3O4 as a core with a 1 m diameter. By combining the sonochemical and hydrothermal methods, we successfully obtained nearly mono-dispersed Fe3O4/BaTiO3 nanoparticle. Cross-section transmission electron and energy dispersive x-ray microscope measurements suggest the clear interface between core and shell. By measuring the electric polarization, dielectric constants under external magnetic field and the magnetization changes near the structural transition temperatures of BaTiO3, we confirm the strain-induced magnetoelectric couplings. Compared with BaTiO3/Fe3O4, the Fe3O4/BaTiO3 nanoparticles show very small electric loss.