Recording physics of keepered inductive media

Basic recording features of keepered media intended for inductive longitudinal recording are investigated. When compared with unkeepered media, the keepered media investigated here are shown to have narrower pulse width, PW₅₀, higher signal and higher medium noise. In agreement with previous models, it is argued that the keeper layer acts as a second read gap and thus creates a flux aperture effect, which reduces the pulse width. We further postulate that the edge of this aperture is an additional noise source. For the Sendust keepered media we evaluated, this additional noise compensates for the signal gain such that the medium signal-to-noise ratio is not improved. Simple model calculations, which treat the keeper as a secondary read gap, are found to qualitatively explain the measured results