Influence of Soft-under-layer in Perpendicular Recording Media on Recording field of Magnetic Duplication

Abstract

The magnetic field distributions around slave media with and without SUL were calculated by using the finite element method to estimate what influence a soft-under-layer (SUL) in a double-layered perpendicular medium had on magnetic duplication characteristics. As a result, we found the SUL enhanced duplication characteristics for any bit length and track width. The SUL in bit printing influences the duplication characteristics more than that in edge printing. The influence of SUL on duplication characteristics in bit printing increases as the strength of the duplication field increases. However, in edge printing, there is a duplication field that maximizes the influence of SUL on duplication characteristics. Moreover, the influence of SUL on duplication characteristics decreases with both bit and edge printing as bit the length of the magnetic pattern decreases, and also decreases as the track width decreases. These dependencies can be explained by taking the demagnetization coefficient of SUL and the total amount of magnetic charge appearing in SUL and magnetic patterns into account.