Prospects for nanoparticle-based permanent magnets

Magnetic nanoparticles smaller than ∼15 nm in diameter and with high magnetocrystalline anisotropies K1 ⩾ 1 MJ m−3 can be used as building blocks for next-generation permanent magnets. Advances in processing steps are discussed, such as self-assembly, alignment of the easy axes and appropriate nanostructuring that will enable the fabrication of densely packed nanoparticle assemblies with improved permanent-magnet properties. This study also proposes an idealized nanocomposite structure for nanoparticle-based future permanent magnets with enhanced energy products.