THE TEMPERATURE-DEPENDENCE OF THE DOMAIN SPACING IN ULTRATHIN MAGNETIC-FILMS

We study the domains in an ultrathin magnetic layer with perpendicular magnetization as a function of temperature. The domain spacing is giv en by the balance between the interface energy and the demagnetizing e nergy. The demagnetizing energy is calculated in a continuum theory wh ich is valid provided that the domains are large compared with the lat tice spacing. The temperature dependence of the interface energy arise s from the entropy of the rough walls. This is obtained from the exact results for the two-dimensional Ising model. We predict that the doma in size shrinks rapidly as the temperature is raised towards the trans ition.