Amorphous and Nanocrystalline Soft Magnets

− The article surveys amorphous and nanocrystalline alloys for soft magnetic applications. Both materials have much in common starting from their way of production and ranging over to the key factors which determine their properties. Thus, the magneto-crystalline anisotropy is randomly fluctuating on a scale much smaller than the domain wall width and, as a consequence, is averaged out by exchange interaction so that there is no anisotropy net effect on the magnetization process − the prerequisite for good soft magnetic behavior. Superior soft magnetic properties additionally require a low magnetostriction which is realized for amorphous Co-based alloys and, more recently, for nanocrystalline Fe-base alloys but at a significantly higher saturation induction and better thermal stability. Both materials reveal low losses up to several 100 kHz and their B-H loop can be tailored by magnetic field annealing according to the demands of application.