Abstract: A magnetic encoder apparatus for determining the position of a moving object. The encoder has a merged magnetoresistive (MR) head capable of maintaining a magnetic transducing relationship with a magnetic medium on a substrate while there is relative motion between the head and the medium. The merged MR head contains an MR read element and an inductive transducer write element. The inductive transducer write element is capable of writing encoded bits that contain information that defines a position of the substrate. The MR read element is capable of reading these encoded bits and generating an output signal. The output signal is processed by electronic circuitry in order to decipher the position of the moving object that is coupled with the encoder.

Abstract: A significantly thinner boron carbide overcoat layer is provided for a magnetic disk which has the same durability as thicker prior art overcoat layers for protecting an underlying magnetic layer. By employing adhesion layers selected from the group consisting of Ge, Ru, WTiSi, WTi, Si, and Y between the magnetic layer and the overcoat layer, the durability of the overcoat layer is significantly increased over a single overcoat layer of B4C. Certain process steps in the making of the B4C overcoat layer still further enhance the durability of the B4C overcoat layer by maintaining the disk or substrate specimen at a floating potential in a plasma chamber and employing low levels of argon pressure and sputtering wattage.