Upper bound to a single-domain behavior of a ferromagnetic cylinder
Amikam Aharoni · Journal of Applied Physics · 1990
For a right circular, finite ferromagnetic cylinder with a radius R, a parameter, Rc1, is calculated so that for R>Rc1 there is always a nonuniform magnetization state whose free energy is smaller than that of the uniform magnetization state. Numerical computations for the cases of permalloy and of magnetite give Rc1, which is quite close to the recently calculated Rc0 in a cylinder of these materials. The latter is defined, as in the fundamental theorem of Brown on spherical particles, so that the lowest free-energy state is that of a uniform magnetization, if R