Supporting data for Thermal Performance of Materials for Heat-Assisted Magnetic Recording

Abstract

Heat-Assisted Magnetic Recording (HAMR) enhances hard disk storage capacity by using localized laser heating to transiently lower the coercivity of high thermal-stability media, enabling nanoscale bit writing. A critical barrier to HAMR implementation lies in thermal management, necessitating accurate determination of material thermal properties across operational temperatures. Here, we investigate the temperature-dependent thermal conductivities (300–500 K) of thin-film materials in HAMR heads—including dielectrics (amorphous SiO₂, Al₂O₃, AlN), metals (Au, Cu), and magnetic alloys (NiFe, CoFe)—using time-domain thermoreflectance. Amorphous SiO₂ and Al₂O₃ exhibit rising thermal conductivity with temperature, consistent with typical amorphous material behavior. In contrast, polycrystalline AlN displays weak thermal anisotropy, with both in-plane and cross-plane conductivities decreasing as temperature increases. These values are substantially lower than those of single-crystal bulk AlN, a consequence of phonon scattering at grain boundaries and defects. Metallic (Au, Cu) and magnetic alloy (NiFe, CoFe) films show negligible thermal conductivity variations across the tested temperature range. For Au and Cu, the suppressed thermal conductivities align with predictions from a diffuse electron-boundary scattering model. These findings establish essential structure-thermal property relationships for optimizing HAMR head materials, particularly highlighting the role of microstructural defects in suppressing heat transfer within dielectric layers while affirming the temperature resilience of metallic components.