Thermal Spin-Torque Heat-Assisted Magnetic Recording

Abstract

In order to achieve higher recording density with lower power consumption than the conventional heat-assisted magnetic recording (HAMR) for next-generation, a more efficient writing with less laser power would be indispensable. An advanced HAMR concept was developed to address such desire, and the write ability was demonstrated in multilayer media stacks comprising the core structures of antiferromagnetic MnPt and ferromagnetic FePt layers with the magnetic easy axis oriented perpendicular to the film plane. The concept is based on two distinct switching mechanisms: thermally activated (TA) magnetization switching and spin-transfer-torque (STT) switching. The latter is driven by an out-of-plane temperature gradient (ΔT) in the MnPt/FePt multilayer which is referred as thermal spin-torque (TST) HAMR media. Pump-probe measurements revealed significant magnetic coercivity (Hc) modulation by ΔT at the local magnetization of the FePt layer. The hybrid mechanism with TA and STT can be separated by sweeping the delay time between the pump and probe laser pulses, and it was found that the STT dominates the mechanism for Hc modulation in the short delay time regime. Furthermore, the modulation of Hc of the FePt layer was demonstrated by varying the magnitude and reversing the direction of steady state ΔT. These results suggest that lower laser power consumption is achievable owing to the contribution of STT assisted switching in the TST-HAMR media.

Keywords: Magnetic recording, spin torque, heat assisted, antiferromagnet