An improved thin film permanent magnet material and novel magnet design for magnetoresistive sensor biasing

A high-performance CoPt thin-film permanent-magnet material and a magnet design have been developed to provide an integrated bias field source for unshielded magnetoresistive (MR) reproduce heads. A 1-μm-thick deposited permanent magnet is located above the MR element and away from the media; it is fully encapsulated and removed from the head/media interface. Problems of mutual demagnetization between magnet and media, galvanic corrosion at the exposed MR and magnet edges, and MR film degradation from an inhomogeneous adjacent permanent-magnet layer are eliminated. A CoPt magnet of specific geometry is designed to produce hard and easy axis bias fields, providing good single-domain stability while maintaining high MR sensitivity. The CoPt sputter deposition is a room-temperature process which is compatible with other temperature-sensitive head materials