Ferromagnetism coercivity

Interest is maintained ia these materials because of the combination of mechanical, corrosion, electric, and magnetic properties. However, it is their ferromagnetic properties that lead to the principal appHcation of glassy metals. The soft magnetic properties and remarkably low coercivity offer tremendous opportunities for this appHcation (see Magnetic materials, bulk Magnetic materials, thin film). 

Hysteresis curves for a magnetically hard and a magnetically soft ferromagnetic material. S = saturation magnetization, R = remanent magnetization, K = coercive force... 

M. Terrones, Controlling high coercivities of ferromagnetic nanowires encapsulated in carbon nanotubes, J. Mater. Chem., vol. 20, p. 5906-5914, 2010. 

FIGURE 11.9 Plot of the magnetic field needed to demagnetise ferromagnetic particles (coercivity, //c) as a function of particle size. The particle becomes single domain at radius Dc. 

Ferromagnetic (In,Mn)As/GaSb heterostructures with rectangular hysteresis show also peculiar light-irradiation effects. In particular, the coercive force is drastically reduced by the illumination, which suggests a reduction of the domain wall pining energy (Oiwa et al. 2001). 

This method is based on the Villari effect applying a uniaxial stress to a ferromagnetic substance induces a magnetoelastic anisotropy which may modify all the parameters of its magnetisation curve, e.g. magnetic susceptibility, coercive force, and so on. Some experimental techniques to measure the strain-induced anisotropy are discussed shortly below. 

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