Effect of laminated crystalline FeCoB soft magnetic underlayer for perpendicular magnetic recording tape media

Abstract

A crystalline FeCoB soft magnetic underlayer (SUL) improves c-axis orientations of the Ru intermediate layer (IML) and the CoPtCr-SiO2 recording layer (RL). (001) orientations of Ru IML and CoPtCr RL are attained by (110) oriented texture of FeCoB SUL. Since good c-axis orientation in CoPtCr-SiO2 RL as well as domain control in the FeCoB SUL is required for high recording density, a laminated FeCoB SUL is prepared as an underlayer of the bilayered Ru/CoPtCr–SiO2 films. A laminated FeCoB SUL results in better (001) orientation in both CoPtCr-SiO2 RL and Ru IML than the single layered FeCoB SUL. This leads to the reduction of media noise in the high recording frequency region. Recording medium layers composed of a laminated FeCoB SUL and bilayered Ru/CoPtCr-SiO2 films deposited on a 4.5-μm-thick Aramid tape show better (001) orientations of Ru and CoPtCr. Media noise of the tape medium with the laminated SUL is lower than that with the single layered FeCoB SUL.