Dependence of the Signal Stability of Double-Layer Perpendicular Magnetic Recording Media on the Directions of the Applied Magnetic Fields

Double-layer media with single-pole heads are ideal for perpendicular magnetic recording. However, the problem of unstable recorded magnetization due to the magnetic domains of underlayers has not yet been solved. We investigated the dependence of the signal stability of a medium with an Ni-Fe underlayer and a medium with an Fe-Si-Al underlayer on the directions of the applied magnetic fields under an SPT head-loaded condition and an ID/MR head-loaded condition. The results show that the recorded signal has better stability with a horizontal field than with a vertical field. They also show that the recorded signal has better stability under the ID/MR head-loaded condition than under the SPT head-loaded condition.