Dynamic coercivity measurements of antiferromagnetically coupled magnetic media layers

We have performed dynamic coercivity measurements on a series of antiferrom agnetically coupled (AFC) magnetic recording media utilizing a static write /read tester. The samples consist of two magnetic layers, which are antifer romagnetically coupled by a nonmagnetic layer. The investigated samples hav e a fixed top layer thickness and variable bottom layer thickness, such tha t the composite remanent magnetization thickness product (M(R)t(AFC)) varie s over a large range, 0.17-0.30 memu/cm(2). We find that the ratio between anisotropy energy and thermal energy (equivalent to stability ratio, C-1), and the intrinsic switching field H-0 are, within the experimental error, c onstant for the series. This suggests that the top magnetic layer to first order determines the stability ratio of the AFC media and that M(R)t(AFC) c an be varied over a large range without decreasing the stability or increas ing the write field requirements. (C) 2001 American Institute of Physics.