Abstract: A magnetic recording medium comprises a non-magnetic substrate having a principal surface, an intermediate layer formed on the principal surface, and a magnetic layer formed on the intermediate layer. The intermediate layer comprises an intermediate material composed of chromium and molybdenum. The magnetic layer comprises a magnetic material composed of cobalt and platinum. The intermediate layer may comprise first and second layers. The first layer comprises a first material composed of chromium and is formed on the principal surface. The second layer comprises a second material composed of chromium and molybdenum and is formed on the first layer.

Abstract: A method of manufacturing a magnetic recording medium by using an in-line sputtering apparatus to successively form, on a substrate, at least one underlying layer, a first magnetic CoPt-based film, a nonmagnetic intermediate film, and a second magnetic CoPt-based film. The underlying film and/or the nonmagnetic film, which are in contact with the first magnetic film, are deposited at a low sputtering power between 100 and 1000 watts to improve the magnetic properties of the magnetic recording medium. Low power sputtering is also effective to improve the distribution of difference of the crystal lattice spacings between the nonmagnetic intermediate film and the first magnetic film and between the underlying layer and the first magnetic film.

Abstract: A method of manufacturing a magnetic recording medium by using an in-line sputtering apparatus to successively form, on a substrate, at least one underlying layer, a first magnetic CoPt-based film, a nonmagnetic intermediate film, and a second magnetic CoPt-based film. The underlying film and/or the nonmagnetic film, which are in contact with the first magnetic film, are deposited at a low sputtering power between 100 and 1000 watts to improve the magnetic properties of the magnetic recording medium. Low power sputtering is also effective to improve the distribution of difference of the crystal lattice spacings between the nonmagnetic intermediate film and the first magnetic film and between the underlying layer and the first magnetic film.

Abstract: A magnetoresistive element is used to detect a surface roughness of an object, such as a magnetic recording medium, a photomask blank, a semiconductor wafer, and is assembled into a reproducing head which moves along a surface of the object and which can produce an electric signal related to the surface roughness. The reproducing head may be incorporated with a recording head into a head unit. The head unit can monitor a magnetic characteristic of the magnetic recording medium in addition to detection of the surface roughness, by recording a predetermined signal by the recording head and by reproducing the predetermined signal by the reproducing head.

Abstract: A diaphragm drive device comprising a first yoke having a plurality of radially extending pole teeth toward the optical axis, a second yoke having a plurality of radially extending pole teeth toward the optical axis, the pole teeth of the first and second yokes alternating each other in a common plane, exciting coils for exciting all the pole teeth of the first and second yokes as held on these yokes, and an apertured disc-like permanent magnet arranged to be rotatable in spaced relation to the plane of the pole teeth of the first and second yokes by a constant axial distance, the magnet being made of a mixture of resin and magnetic materials by molding techniques and magnetized in such a way that the magnetic axes of the domains of the magnetic material are oriented toward only one of the radial surfaces of the disc, wherein the apertured disc-shaped permanent magnet is drivingly connected to the diaphragm blades.