THEORY OF INTRINSIC-COERCIVITY IN NARROW MAGNETIC DOMAIN-WALL MATERIALS

A theory for intrinsic coercivity in a narrow magnetic domain wall material is proposed. Results from non-linear mathematics are used to represent magnetic domain walls as solitary-wave or soliton excitations. By applying the perturbation of a discrete lattice to the continuum sine-Gordon equation, a scattering (pinning) of the soliton (domain wall) is obtained, with a strong onset occurring when the domain wall width becomes comparable with a few lattice spacings. Correlation between this effect and the intrinsic (i.e. not defect dependent) coercivity is made. Specific examples are given using the RCo 5xNi5-5x and RCo5xCu5-5x systems which exhibit narrow domain walls.