Read/write simulation of keepered medium·thin film head system

Two-dimensional read/write simulation based on the Maxwell equations is performed on a keepered medium (KM) with a thin soft magnetic layer (keeper layer) over a recording layer and a thin film head system by a finite element method. The keeper layer with the relative permeability μ of 100 and the thickness t of 15 nm reduces the demagnetizing field in the recording layer (Mr=560 kA/m, t=36 nm, Hc=167 kA/m) by 1/2, and as a result, the recorded magnetization increases by 1/4. The optimum μ of the keeper layer lies between 80 and 140. The spacing loss for an unkeepered medium (UKM) is consistent with the theory, but the one for the KM decreases considerably for low magnetic spacings. The magnetic spacing of 30 nm for the KM is equivalent to that of 13 nm for the UKM