Origin of incoherent magnetic switching behavior in CoCrPt-SiO2 perpendicular magnetic recording media

Magnetic switching behavior for CoCrPt-SiO2 single layer media with oxygen contents (OCs) from 4% to 10% and recording layer thickness (t(mag)) from 2 to 27 nm is investigated. Significant incoherent switching, caused by domain wall motion, and large activation volume are observed at t(mag)<= 6 nm regardless of OC, consistent with nonuniform microstructure with less grain isolation at t(mag)=4 nm. These results support formation of a highly exchange-coupled thin magnetic layer on top of Ru interlayer, which can explain the large difference between angular dependence of H-cr predicted by the Stoner-Wohlfarth theory and the experimental values. (C) 2007 American Institute of Physics.