FMR, Magnetization, and Dynamic Coercivity Studies of Anisotropy in CoCrPtB Recording Media

Methods to determine magnetic anisotropy in materials with a 2D inplane distribution of anisotropy axes are compared. We show that high field ferromagnetic resonance (FMR) and the Miyajima method give identical results providing the later is analyzed correctly. Extrapolation of the time dependence of coercivity using Sharrock's equation gives lower anisotropy values and this is shown to be due both to extrapolation errors and the effect of interactions. Additionally, the inhomogeneous broadening of the FMR line provides information on the effective distribution of anisotropy which we correlated with recording performance for a series of CoCrPtB media as a function of boron content