Effect of underlayers on magnetic properties of Co/Pd multilayer perpendicular magnetic recording media

Amorphous C and Si films were sputter-deposited as underlayers of Co/Pd mul tilayer perpendicular magnetic recording media. The magnetic properties of the media were significantly affected by the underlayer thickness; namely, the values of coercivity He and nucleation field -H-n increased and the val ue of alpha decreased with merely increasing the thickness of C or Si under layer. where alpha is the derivative of M-H loop at the value of coercivity . The coercivity was not always affected by magnetic anisotropy constant K- u for the Co/Pd media. In read-write experiments, the higher S/N ratio was obtained for the media with the thicker C or Si underlayer, which exhibited low alpha and high H-c. In the time decay experiments of magnetization, th e Co/Pd multilayer media with C or Si underlayer possessed good thermal sta bility. This study demonstrated that the introduction of C or Si underlayer greatly improves magnetic properties, read-write characteristics, and ther mal stability of Co/Pd multilayer perpendicular magnetic recording media. ( C) 2001 Elsevier Science B.V. All rights reserved.