Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. and 0.1 to 10 at. of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained. A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.

Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.

Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.

Abstract: A magnetic recording medium including a substrate and a magnetic layer on the substrate which is a Co-based alloy including Pt and/or Ir, including at least one of Ti, Zr, Hr, V, Nb, Ta, Cr, Mo, W, Ge, and Si, and including oxygen. A magnetic memory apparatus including the magnetic recording medium.

Abstract: In order to provide a magnetic disk apparatus and a magnetic disk which is excellent in reliability and durability, and which enables high density recording, respectively, this invention provides a method for forming fine concave and convex portions (uneven area) on the magnetic disk by coating masking material particles only in the CSS area on the magnetic disk, etching the magnetic disk, and removing the masking material particles.

Abstract: To provide a magnetic disk excellent in floating and sliding characteristics in a low floating area. A magnetic disk having a feature that variations in the height of the projections on each surface of protective films in floating ensured areas on both sides of the magnetic disk are .+-.15%, and a magnetic disk device on which the magnetic disk is mounted.

Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.

Abstract: A magnetic recording medium that uses, as a protective coating layer provided on a magnetic layer for magnetically recording signals, a layer made of a nonmagnetic material consisting of two ore more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, and B, or made of a magnetic material consisting of one or more elements of Co, Fe, Ni, and Gd, one or more elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W, and one or more elements of N, C, O, B, and Si is excellent in sliding endurance. When the protective coating layer is made of the nonmagnetic material, the magnetic recording medium is also excellent in corrosion resistance, and when the protective coating layer is made of the magnetic material, the spacing between a magnetic head and the magnetic recording medium can advantageously be made large. Both the cases are high in reliability, and suitable for high density magnetic recording.

Abstract: A magnetic recording medium for longitudinal recording with a low media noise, a high S/N ratio and high reliabilities in corrosion resistance is disclosed. By making a magnetic layer from a Co-based alloy comprising 1 to 35 at. % of at least one element selected from the group consisting of Pt and Ir, 1 to 17 at. % of at least one element selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W. Ge and Si, except for Si, whose concentration is 1 to 40 at. %, and 0.1 to 10 at. % of oxygen, a magnetic recording medium for longitudinal recording having an inplane coercivity of 1,200 Oe or more and a coercive squares of not more than 0.85 is obtained.A process for producing the magnetic recording medium for longitudinal medium and a magnetic memory apparatus using the magnetic recording medium for longitudinal recording are also disclosed.

Abstract: A semiconductor laser device is capable of producing an increased optical output power with improved optical characteristics without being subjected to mode distortions in the output beam, while retaining advantageous features inherent to a semiconductor laser device of a buried heterostructure. The semiconductor laser device comprises an optical confinement region which is constituted by at least first, second, third and fourth semiconductor layers successively laminated on a predetemined semiconductor substrate. The second semiconductor layer has a relatively small refractive index and a relatively wide band gap as compared with those of the third semiconductor layer, while the first and the fourth semiconductor layers which are of the conductivity types opposite to each other have relatively small refractive indexes as compared with the second and the third semiconductor layers.

Abstract: A semiconductor laser device capable of emitting highly collimated beams, especially of a narrow beam divergence, is disclosed. A striped hetero-junction is formed on a predetermined semiconductor substrate by a first semiconductor layer (refractive index: n.sub.1, band gap: Eg.sub.1, thickness: d), a second semiconductor layer (n.sub.2) and a third semiconductor layer (n.sub.3), and the hetero-junction is sandwiched between portions of a fourth semiconductor layer (n.sub.4, Eg.sub.4) into a buried structure. At this time, the various materials are selected to follow the relations of d.ltoreq..lambda. (where .lambda. denotes the oscillation wavelength of the semiconductor laser), n.sub.2, n.sub.3 <n.sub.4 <n.sub.1, and Eg.sub.1 <Eg.sub.4, and the effective refractive index of the first semiconductor layer (n.sub.1eq) is made smaller than n.sub.4.