Optimum disk structures and energetics of domain formation in magneto-optical recording

A quadrilayer magneto-optical device in which the magnetic medium is sandwiched between two dielectric layers and supported by a reflecting substrate is shown to have desirable characteristics for both the storage and retrieval of information, The quadrilayer exhibits a readout signal to noise ratio of about 8 (3) dB over the readout from bare (coated) bulk material. At the same time, the writing sensitivity is matched to the available laser power for recording, thus permitting high levels of read power without loss in resolution. Energetics of domain formation in a ferrimagnetic material during a typical write cycle is then examined. Contributions from different sources of energy are compared and the role of coercivity in the formation and stability of domains is discussed.