Dual-layer carbon-based protective overcoats for recording media by filtered cathodic ARC deposition

摘要

A recording medium, comprising:(a) a substrate having at least one surface;(b) a stacked plurality of thin film layers on the at least one surface and including at least one magnetic or magneto-optical (MO) recording layer; and(c) a protective overcoat layer on an outer surface of an outermost layer of the layer stack, comprising: (i) a first sub-layer layer (c₁) of undoped tetrahedral amorphous carbon (ta-C) formed by filtered cathodic arc deposition (FCAD) on the outer surface of the outermost layer of the stacked plurality of thin film layers and having a high mass density of carbon (C) atoms greater than about 2.5 gms/cm³; and(ii) a second sub-layer (c₂) of nitrogen-doped tetrahedral amorphous carbon (ta-C:N) formed by FCAD on the undoped ta-C layer and having a high mass density of carbon (C) atoms greater than about 2.0 gms/cm³.