Rayleigh law
(重定向自Rayleigh constant)
The Rayleigh law describes the behavior of ferromagnetic materials at low fields.
Ferromagnetic materials consist of magnetic domains. When a small external field is applied, domains parallel to the external field start to grow. In this region, domain walls are moving. They are hindered by material defects. Lord Rayleigh investigated this first and quantified the magnetization
as a linear and quadratic term in the field: