抄録
The spontaneous magnetization of ferromagnetic thin films is calculated by the spin wave theory under the same boundary condition for the transverse magnetization as derived by Pincus, and its dependence on temperature, thickness and surface anisotropy is discussed. A numerical evaluation in the limiting case of infinite surface anisotropy shows that the M(T) (magnetization vs temperature) varies with temperature more slowely in thin films than in bulk materials and the magnitude of M(T)⁄M(0) is larger in thinner films at a fixed temperature. It is shown qualitatively that the magnetization of thin films decreases with reduced surface anisotropy to a lower value than in the bulk, so that for an appropriate value of the surface anisotropy the temperature dependence of magnetization in thin films is expected to be similar to that in the bulk, as observed.
