<title>Figures of merit for recordable optical media</title>

Although magneto-optic materials are often characterized and compared by misleading `figure of merit' (such as Kerr rotation), the Lissberger-Mansuripur figure of merit has many advantages. Using this figure of merit we can directly study, for example, the effect on the MO signal of Pb or Bi in nanolayered TbFeCo. No comparable figure of merit has been available for optimizing phase change materials in optical media. In this paper we show how the Lissberger- Mansuripur figure of merit can be extended to phase change materials, and we calculate its value for GeSbTe.