Study on magnetization reversal of perpendicular recording media by in-field MFM observation

In-field MFM observation technology was employed to study the perpendicular recording medium under various perpendicular magnetic fields. A magnetization reversal field (H-R) map method was performed to reveal the magnetization reversal behavior of the medium. Under low magnetic field, some specific areas firstly reversed at a random position and then these reversed areas grew up. Under a high magnetic field, the magnetization reversal process tended to occur at the boundary between the reversed area and the non-reversed area. The simulation results implied that the long-range spatial interaction exists in the real media, which results in the bigger magnetic cluster. A simple experimental method was first proposed to estimate activation volume. The experimental activation volume agreed with the result calculated by the dynamic coercivity method. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.