Magnetic properties and media noise of Co-Ni-P plated disks

Abstract

Magnetic properties and read-write characteristics of Co-Ni-P plated disks are examined. In-plane coercive force and squareness increase with increasing the thickness of an Ni-P layer which is formed between the substrate layer (Cu-Sn) and Co-Ni-P film. However, media noise increases with thickening of the Ni-P layer. The relationships between magnetic properties and media noise are investigated by measuring rotational hysteresis (Wr) and its integral (RH). As a result, it is found that media noise closely correlates RH values: smaller RH values cause less media noise. This result shows that media noise is dominated by the magnetization process, and magnetic thin film in which the magnetization process occurs through coherent rotation is desirable for magnetic recording media.