Thermal wave interactions in magnetic materials

A technique to sense the magnetic characteristics of the individual layers of a multilayer structure is demonstrated. It detects the interaction between a thermal wave and the magnetization dependent thermal transport properties of the medium. A modulated laser beam is used to generate a thermal wave at the surface of a thin film sample and launch it into the medium. The amplitude and phase of the wave are modulated by the thermal properties of the medium as it propagates. Initial results for a AgNiFe magnetic thin film under a non-magnetic overlayer have successfully measured the magnetization dependent thermal conductivity. The measurements agree well with those obtained from the magnetization dependent resistivity.