Dynamic coercivity measurements of antiferromagnetically coupled magnetic media layers

Abstract

We have performed dynamic coercivity measurements on a series of antiferromagnetically coupled (AFC) magnetic recording media utilizing a static write/read tester. The samples consist of two magnetic layers, which are antiferromagnetically coupled by a nonmagnetic layer. The investigated samples have a fixed top layer thickness and variable bottom layer thickness, such that the composite remanent magnetization thickness product (M Rt AFC) varies over a large range, 0.17-0.30 memu/cm2. We find that the ratio between anisotropy energy and thermal energy (≡ stability ratio, C-1 ), and the intrinsic switching field H0 are, within the experimental error, constant for the series. This suggests that the top magnetic layer to first order determines the stability ratio of the AFC media and that M Rt AFC can be varied over a large range without decreasing the stability or increasing the write field requirements. © 2001 American Institute of Physics.