Lorentz microscopy studies of magnetization patterns recorded on a real disk

Abstract

In this paper we describe a new method for producing samples with large thin areas for Lorentz TEM observation of recorded magnetic domain patterns in production-quality thin-film rigid disks. In this method, as applied in this paper to the study of electroplated Co-Ni-P media, a strippable metal layer is introduced beneath the magnetic layer, along with plated Ni-P which provides a sublayer for magnetic film growth comparable to the normal polished electroless nickel substrate. In this way one can produce a magnetic layer identical to that on a real disk, write data on the disk with a flying head, and then remove the magnetic layer for TEM analysis. We also describe some typical applications of the new method, including a comparison of magnetic domain structure at recorded transitions in high- and low-noise media, and an illustration of the effect of head pole geometry on bit-cell shape.