Thermoreflection measurement of magnetic thin films

With recent developments in Heat Assisted Magnetic Recording (HAMR), there is growing intense interest in the thermal-optical properties of the HAMR media. We detect the phase change of the optical beam as it reflects from a FePt thin film under strong thermal gradient by carrying out Close-Aperture reflection Z-scan experiments. It was found that the far field spatial distribution of the reflected beam is sensitive and dependent on the thermal field distribution in the media. This experiment technique can be extended to study the spatial distribution of the thermal field in the HAMR media and to enable temperature measurement of HAMR media under laser irradiation.