Novel approaches to high-density perpendicular recording media

Two different approaches to reduce the intermediate layer (IL) thickness in perpendicular recording media are proposed. Such a reduction in IL thickness could lead to improvement in writability and recording performance. The first approach involved the introduction of a magnetic intermediate layer (MIL), to obtain C-axis growth. Media with CoCr alloy layer as the MIL were studied. Reasonably good C-axis growth with a Δθ50 of about 3.8° could be obtained for MIL thickness of about 10 nm. Noise could be controlled by introducing exchange-breaking layers. The other approach involved the use of crystalline soft underlayers (SUL) to obtain suitable growth conditions for the recording layers. For this purpose, CoFeTaCr alloys with a FCC(1 1 1) texture were prepared. A good C-axis dispersion in the recording layer with a Δθ50 of about 3.1° could be obtained for IL thickness of about 5 nm. The present study indicates that the recording medium deposited on crystalline SUL is relatively noisier than that deposited on amorphous SUL. Reducing the noise of the crystalline SUL is a way towards higher areal densities.