Growth and micromagnetic simulation of magnetite nanoparticles

Magnetite nanoparticles with different sizes and different assemblies were synthesized via hydrothermal method. Micromagnetic simulation shows the magnetite nanocubes with different sizes have different energy states, which determines the assembly mode. Magnetite nanocubes with the side length of 30–60 nm tended to be dispersed while both nanochains and dispersed nanoparticles were found to grow for the nanocubes with the side length less than 30 nm, which can be explained in the fact that the above two assembly modes have very close energies. The assembly mode of nanocubes with the size bigger than 60 nm is generally nanorings consisting of connected inter-grown nanocubes and the nanocubes are no longer single domain. The simulations are consistent with the experimental results.