Mechanism of quasilinear temperature dependence of the surface magnetization in a semi-infinite ferromagnet

A semiclassical method involving surface spin waves is used to calculate the spontaneous magnetization M near the surface of a semi-infinite ferromagnet. The magnitude of the surface anisotropy constant Kₛ introduced by N\'eel is assumed to be negligible compared to the magnitude of the surface anisotropy constant Kₛₛ introduced by the present author. It is shown that under these conditions any positive value of Kₛₛ causes the dependence of M on the temperature T to be quasilinear rather than proportional to T3/2 and the dependence of M on position to be exponential. This surface-anisotropy-based mechanism contains a weakened-surface-exchange model as a special case. The theoretical predictions are found to provide a possible interpretation of recent experimental results on MnF₂-covered Fe(110).