Magnetic nanocomposites comprised of nano-sized magnetic crystals embedded in an amorphous matrix have been shown to have excellent soft magnetic properties. In particular, amorphous and nano crystalline materials have been investigated for various soft magnetic applications including transformers and inductive devices. The historical development of nanocomposite soft magnetic materials will be reviewed. In these materials it has been determined that an important averaging of the magnetocrystalline anisotropy over many grains coupled within an exchange length is at the root of the magnetic softness of these materials. The crystallization kinetics and the chemical partitioning occurring during crystallized ion will be described.

Soft magnetic materials face demanding requirements from new, high-performance electronic and power distribution systems. The new systems must operate in high-temperature and high-frequency regimes that are inaccessible to conventional crystalline and amorphous magnetic materials. The need for increased energy efficiency requires reduced power loss from inductive components. Nanocrystalline magnetic materials hold promise for meeting these requirements without resorting to the trade-offs needed when using conventional materials

A material that maintains a remnant magnetization, Mr, in the absence of an applied field is known as a ferromagnetic material. Ferromagnets are the most widely used type of magnet, and are typically referred to as magnetic materials or magnets. A finite field known as the coercive field, Hc, is used to reverse the Mr. When driven with an applied field a ferromagnet reaches a saturation magnetization, MS, that is an intrinsic property of the material. The magnet's permeability, μ, reflects the ease with which it is magnetized and is an extrinsic property that depends on the microstructure of the material.