Energetics of domain formation in thermomagnetic recording

Abstract

A new model for the distribution of perpendicular magnetization in thin magnetic films supporting a circular domain is proposed. The contributions of various sources to the magnetic energy are determined and the demagnetizing effect in particular is discussed at length. It is shown that a demagnetizing energy density per unit area of the domain wall can be defined which, unlike the domain wall energy density arising from exchange and anisotropy contributions, is a function of film thickness h. For domains of large radius and small wall thickness (compared with h), the demagnetizing energy density is found to be linearly increasing with h. A typical cycle of thermomagnetic recording on a thin ferrimagnetic film with room temperature compensation point is then studied, and the effect of various parameters on the formation process and stability of reverse magnetized domains is discussed.