Crystalline, shape, and surface anisotropy in two crystal morphologies of superparamagnetic cobalt nanoparticles by ferromagnetic resonance

Superparamegnetic cobalt nanoparticles (NP's) with different crystalline structures and sizes raging from 4 to 9 nm in diameter is investigated using ferromagnetic resonance (FMR) techniques. The results from both single crystalline and polycrystalline cobalt NP's reveal that a particle's effective anisotropy and thus its magnetic properties, are extremely sensitive to internal structure and overall shape.