Approaching the Grain-Size Limit for Jitter Using FeRh/FePt in Heat-Assisted Magnetic Recording

Composite FeRh/FePt for heat-assisted magnetic recording media is investigated with micromagnetic simulation. It is found to potentially lower recording temperature, while retaining high anisotropy field gradient. The transition width is predicted to depend on the media cooling rate. The thickness of the FeRh layer and the applied field can significantly affect the switching time of the FePt layer, and therefore alter recording performance. Applied field magnitudes and angles are identified that allow successful switching within 100 ps. It is shown that using up to 15 nm of FeRh with 6 nm of FePt, the jitter for 5.6 nm grains can be nearly equal to the grain-size limited value, for head velocities as high as 20 m/s.