Anisotropy of wall energy in orthoferrites

Wall anisotropy causes bubble domains to be elliptical. A formula relating the eccentricity of an elliptical bubble to the anisotropic wall energy is derived, and an experimental technique for measuring the wall anisotropy is described. In Sm
0.55
Tb
0.45
FeO
3
a measured anisotropy energy of 1.7 percent of the wall-energy density at room temperature is responsible for eccentricities as large as 0.4 at average bubble radii equal to 85 percent of the bubble strip-domain transition radius. The relationship between material parameters and wall-energy anisotropy is briefly discussed.