Thermophysical characterization of amorphous NiTa thin films for heat-assisted magnetic recording using frequency-domain thermoreflectance

The rapid global growth in data volume has intensified the need to increase the recording density of hard disk drives (HDDs) while reducing storage costs. Heat-assisted magnetic recording (HAMR), a next-generation HDD technology based on laser-induced heating, requires accurate thermal design of the recording medium for high performance. This study examines the thermophysical properties of amorphous NiTa, a candidate material for heat sinks and adhesion layers in HAMR devices. Frequency-domain thermoreflectance measurements were performed on NiTa films with thicknesses ranging from 5 to 500 nm. The volumetric heat capacity was first determined using sufficiently thick samples, after which the effective thermal conductivity was measured across the full thickness range. The measured values, which include interfacial contributions from the glass substrate and aluminum transducer, were analyzed using a series resistor model. Fitting across all thicknesses yields a thermal conductivity of 6.8±0.3 (W m−1 K−1) for NiTa. The results indicate that the thermal conductivity remains practically independent of film thickness, consistent with typical transport characteristics of amorphous materials. Furthermore, the thermal conductivity of NiTa thin films is one to two orders of magnitude lower than that of representative crystalline metallic materials.