Abstract: An improvement in production of an optical recording medium of phase change type is provided. In the present method, the step of repeated recording and erasing which had to be carried out after initialization and before shipment in the conventional process is eliminated. The optical recording medium produced by the present process retain good properties after repeated overwriting. In the process of the present invention, the prior art initialization step is replaced by modification treatment and the subsequent crystallization treatment. The modification treatment is a step wherein non-crystalline recording layer formed by sputtering is melted and cooled to change the crystal-lographic state into a non-crystalline state which is different from the non-crystalline state immediately after the formation of the recording layer. The crystallization treatment is a step conducted after the modification treatment wherein the recording layer in non-crystalline state is heated for crystallization.

Abstract: A magneto-optical disc (1) includes a write/read magnetic layer (4) with high coercivity on a substrate (2) and an auxiliary magnetic layer (6) with low coercivity thereon in a magnetostatically coupled manner. Both the magnetic layers are recorded. Prior to or during reading, an external magnetic field of controlled strength is applied to initialize the auxiliary magnetic layer (6). The recorded magnetization information in the write/read magnetic layer (4) is read out by irradiating reading light from the side of write/read magnetic layer (4). Reading with improved C/N is possible.

Abstract: In a magneto-optical recording medium comprising a first dielectric layer, a recording layer, a second dielectric layer, and a metal reflective layer stacked on a substrate, the second dielectric layer is formed of a mixture of a rare earth element oxide, silicon oxide, and silicon nitride. The medium has increased recording sensitivity and provides stable recording/reproducing performance with low error rate and high resolution.

Abstract: This invention has for its object to provide a magneto-optical recording medium at low costs, which is high in magnetic field sensitivity and reliability, and enables high C/N to be obtained even at high linear velocity.The magneto-optical recording medium of this invention includes on a substrate a first dielectric film, a recording film of a rare earth element-transition element alloy (including Fe), a second dieleetric film containing a metal element M and nitrogen N and a reflective film. In this medium, the recording film is up to 65 nm in thickness, and the respective diffusion indices of oxygen, nitrogen and metal element M in the vicinity of the boundary between the second dielectric and recording films are within the predetermined ranges, when the element distribution is measured by Auger electron spectroscopy under the predetermined conditions. The maximum value of the oxygen content in the vicinity of said boundary is 5 to 25 at %.

Abstract: In a magneto-optical recording disc of the magnetic field modulation recording mode, recording of information for the first time is carried out in an optical modulation mode at a linear velocity which is higher than a reading linear velocity. The time required for recording is reduced while the recorded disc produces satisfactory outputs on playback.

Abstract: A magneto-optical disc is fabricated by forming a first dielectric film, a recording film of a rare earth element-transition element alloy, and a second dielectric film on a transparent substrate in the described order and further forming an intermediate film between the recording film and the second dielectric film. The second dielectric film contains at least one metal element and nitrogen. By depositing Ti, Cr or Nb to form an intermediate film of 1-28 .ANG. thick, the disc is improved in magnetic field sensitivity and reliability. By depositing Co or Ni to form an intermediate film of 1-18 .ANG. thick, the disc is improved in magnetic field sensitivity and reproduction stability.

Abstract: An optical recording medium comprising a recording layer on a substrate and an intermediate layer between the substrate and the recording layer exhibits high reflectance and corrosion resistance when the intermediate layer comprises silicon, aluminum, oxygen, nitrogen, and at least one element selected from the group consisting of yttrium, lanthanide elements and actinide elements, and contains 0.1 to 2 atom % of the element and 20 to 90 atom % of silicon and nitrogen combined or 2 to 35 atom % of the element and 20 to 95 atom % of silicon and nitrogen combined.

Abstract: In a magnetooptical recording medium comprising a first dielectric layer, a recording layer, a second dielectric layer, a metal reflective layer, and a protective coat on a substrate, magnetooptical recording is carried out in a magnetic field modulation mode using recording light. The first dielectric layer is thinner than the thickness corresponding to the primary minimum reflectivity in the reflectivity versus thickness curve of dielectric layer measured at the light wavelength. This provides an increased recording sensitivity and an increased recording power margin over which recording/reproducing operation can be carried out at low error rates and high resolution.

Abstract: A magneto-optical disk is made up of a disk form of substrate including on its surface a recessed area having at least one of a groove and pits, and a recording layer provided such that it covers the recessed area. The geometry of at least one of the groove and pits is designed to conform to .theta..sub.10 .gtoreq..theta..sub.50 and .theta..sub.50 >.theta..sub.90 where .theta..sub.10, .theta..sub.50 and .theta..sub.90 are respectively the angles that tangential lines make with horizontal lines at 10%, 50% and 90% depth positions of a side wall of the recess in the diametrical direction of the substrate. This magneto-optical disk is improved in terms of the push-pull signal level, radial contrast, skew margin and C/N.

Abstract: An optical recording medium comprising a recording layer on a substrate and a protective layer formed adjacent to the upper or lower surface of the recording layer is more durable and corrosion resistant when the protective layer has a composition comprising silicon, a divalent metal such as Ba, Ca or Sr, oxygen, and nitrogen. An intermediate layer containing silicon, a metal or metalloid such as aluminum or lanthanum, oxygen and nitrogen is formed between the protective layer and the recording layer.

Abstract: An optical recording medium comprising a recording layer on a substrate and a protective layer formed adjacent to the upper and/or lower surface of the recording layer is more durable and corrosion resistant when the protective layer has a composition comprising, in % by weight, 40-60% of SiO.sub.2, 0.5-10% of an alkali metal oxide, 10-59.5% of Al.sub.2 O.sub.3 and/or B.sub.2 O.sub.3, and optionally up to 50% of a divalent metal oxide.