Orbital Driven Heat Assisted Magnetic Recording with FePt-BN Granular Media

The heat assisted magnetic recording (HAMR) system provides hard-disk-drives with huge data storage capacity. We experimentally validate enhanced writing efficiency of the FePt granular media through magnetic coercivity modulation due to out-of-plane temperature gradient (ΔT). The media: MgO substrate//VN(10 nm)/{MTO, TiO}(2 nm)/granular FePt-BN(5 nm) are deposited using a magnetron sputtering technique. The hysteresis loops are measured via the pump-probe magneto-optical Kerr method to investigate the time evolution of instantaneous coercivity (Hic) after the pump laser excitation. The Hic clearly decreases from the coercivity without pump laser for the VN/TiO/FePt-BN, which is more prominent compared to the VN/MTO/FePt-BN and controlled VN/FePt-BN media. These results suggest that TiO insertion plays a significant role to boost writing efficiency by spin-torques originating from orbital current injection driven by the out-of-plane ΔT, which is referred to as the thermal orbital torque (TOT)-HAMR, promising pathway to an advanced HAMR concept.