Abstract: An optical card comprises a transparent substrate having a track groove on its surface, an optical recording layer provided on said track groove, and an opaque card substrate provided in such a manner that it may be contiguous to said optical recording layer, wherein an unrecordable part is provided at an end of said track groove formed on the surface of the transparent substrate.

Abstract: An optical phase change media comprises a substrate, an active layer having a crystalline and a liquid state, a dielectric layer and a reflective layer. The active layer is of a thickness which will transmit incident light. The dielectric layer is of a thickness such that light passing through the active layer is reflected by the reflective layer and destructively interferes with the incident light reflected directly off of the active layer, thereby causing the crystalline state of the active layer to absorb more light than the liquid state. The result is that the media experiences reduced temperature during writing.

Abstract: The optical recording member according to the present invention includes an information recording pattern consisting of high reflectance portions and low reflectance portions formed on a substrate. During reading of information, discrimination of recording information is done by detecting the difference in light reflectance between the above respective portions. In this case, the low reflectance portions are roughened on their surface and have light scattering property, and therefore the difference in light reflectance can be well detected. Further, the method for preparing the optical recording member according to the present invention can be practiced according to relatively simple means of the surface roughening step of the above low reflectance portions and yet according to a precise and rapid method, and therefore it is suitable for bulk production on an industrial scale.

Abstract: An optical recording medium is formed by applying a coating liquid to form a light-reflecting layer on a substrate having a surface provided with a pre-format pattern comprising a concavity and a convexity. The concavity is designed to have a sectional shape of a trapezoid having a pair of parallel opposite sides, a shorter one of which constitutes the bottom of the concavity, and a pair of sloping sides. Each sloping side forms a (solid part) angle .theta. of not larger than 35 degrees with respect to the extension of the substrate surface. The concavity has a depth d larger than .lambda./4n wherein .lambda. is the wavelength of an optical radiation beam with which the optical recording medium is illuminated for recording and/or reproduction and n is the refractive index of the substrate.

Abstract: The present invention provides a read-write head for an optical tape recorder comprised of a synchronized scanning transmissive polygon and rotating lens wheel. The transmissive polygon is a multi-sided piece of transparent optical quality material for displacing a through transmitted collimated read or write light beam. The lens wheel comprises a unitary disk-shaped piece of optical quality material having a plurality of individual lenses precision molded or diamond point turned therein for focusing the through transmitted and displaced read or write light beam onto a recording media. The polygon is rotated to translate the displaced beam for scanning along a linear path aligned with an arcuate path followed each successive lens on the rotating lens wheel. The rotation of the polygon and lens wheel are synchronized such that each scan of the displaced beam along the linear path coincides with the movement of a lens along the arcuate path to trace out a data track on the recording media.

Abstract: The invention relates to a method of manufacturing a metal matrix suitable for use in the manufacture of optical discs, in which a master plate is used which comprises a recording double layer of a synthetic resin in which each layer comprises a laser light-absorbing dye, the master plate is exposed to modulated laser light in which the laser light in both layers of the recording layer is absorbed and in which as a result of the exposure information bits are formed in the form of bumps having variable longitudinal dimensions and the same width dimensions and the master plate on the side of the recording layer comprises a metal layer which is separated from the master plate, as well as a master plate which is suitable for use in the method described hereinbefore.

Abstract: An optical recording medium capable of reproduction in accordance with the CD standard is provided. The medium includes a reflective thin film of Ag or similar element, an intermediate thin film of Zn or similar element, and a low-melting thin film of Te or similar element wherein light irradiation causes the reflective thin film element and the low-melting thin film element to diffuse into each other to form an alloy or compound of reduced reflectivity. It is possible to determine through simulation a combination of atoms of the respective thin films which form a cluster having HOMO where electrons in the reflective thin film atoms and electrons in the low-melting thin film atoms do not form a hybrid orbital and LUMO where electrons in the reflective thin film atoms and electrons in the low-melting thin film atoms form a hybrid orbital.

Abstract: An optical recording system. The system is directed towards optical recording media which is responsive to at least two wavelengths of light such as an erase beam and a record beam. Light of a lower wavelength is produced by a divergent light source such as a diode and only partially collimated in a collimating lens. When the record and erase beams pass through a common objective for focusing on the recording media, the slightly divergent lower wavelength beam is focused at the same location as the fully collimated higher wavelength beam.

Abstract: An information storage medium comprises a substrate and a recording layer supported on the substrate and subjected to reversible and selective phase transformation between different phases, by changing the conditions under which a light beam is radiated. The recording layer contains an alloy represented by (In.sub.100-x Sb.sub.x).sub.100-y Te.sub.y (where x and y are in atomic %, 45.ltoreq.x.ltoreq.50, and 25.ltoreq.y.ltoreq.45).

Abstract: An optical information recording medium is manufactured by a so-called photopolymerization process. The medium comprises a glass substrate and a layer of ultraviolet ray setting resin having a surface which is a replica of a stamper. Concentric recesses are formed at the outer and inner peripheral edges of the glass substrate to receive an excess resin to avoid any formation of a bur on the finished disk medium.

Abstract: An optical storage medium is disclosed. In general, the storage medium includes a substrate, with a first, expansion layer, a second, reflective layer bonded to the first layer, and a third, retention layer bonded to the second layer, opposite the first layer. An opto-electronic system for recording data is also disclosed, along with a method of manufacture of the storage medium.

Abstract: A head and media for optical data storage with a media in which a partially light transmissive recording layer and a reflective layer are located on opposite faces of a transparent substrate layer. The head emits a light beam which passes through the recording layer, transits the substrate layer, reflects internally off the reflective layer, transits the substrate layer in the opposite direction, and comes to focus on the recording layer. This optical path is used for reading and writing. Two of these optical media, placed back to back, with recording layer faces outward, can be used to form a double-sided media with read and write capability from either side. In a magneto-optical system, since the recording layer is near the outer surface, both the optical and magnetic heads can be located and moved as a single unit, increasing the speed and reliability and reducing the cost.

Abstract: An optical disk structure for an erasable optical disk for use with an erasable optical disk drive using electron trapping optical memory media is disclosed in which several distinct layers in addition to the electron trapping optical memory media are utilized in order to minimize light scatter between adjacent tracks on the disk and to carry permanent format and guidance information for use in acccomplishing the write, read and focusing and traking functions of the erasable optical disk drive with which the disk structures are utilized. The use of absorbing layers as part of the optical disk structure for attenuating reflections of light within the disk structure and eliminating the spreading of marks is also disclosed.

Abstract: There is disclosed an over-write capable magnetooptical recording medium, which includes a substrate having spirally or concentrically formed land portions, and grooves formed between the adjacent land portions on its surface, and at least two layers including a memory layer having perpendicular magnetic anisotropy, and a writing layer exchange-coupled to the memory layer, and having perpendicular magnetic anisotropy, the stacking order of these layers not being specifically limited, characterized in that the depth of each of the grooves is set to be 800 .ANG. or less. The groove depth is preferably 300 .ANG. or more for tracking. Within this groove depth range, a C/N ratio can be higher than a case wherein a groove has a depth larger than 800 .ANG..

Abstract: Disclosed is an optical information recording medium which comprises an active layer which undergoes phase change upon irradiation with light and protective layers formed on both the sides of the active layer, wherein the thermal capacity of the active layer which is a heat source is decreased, a reflection layer of high thermal conductivity is provided on the protective layer to cause increase of the coefficient of lines expansion of the protective layer with increase in distance from the active layer or the thickness of each layer is specified to make nearly the constant maximum temperature by irradiated light against a change in the thickness of the active layer.

Abstract: A method of manufacturing an optical disk on which light-emitting regions for absorbing a laser beam and emitting light of a wavelength different from that of the laser beam and reflection regions for reflecting a laser beam irradiated thereon are alternately arranged, comprises the steps of forming a reflection layer on a transparent substrate, forming a plurality of through holes in the reflection layer, and filling a light-emitting layer consisting of a fluorescent member in the through holes, thereby a high density optical disk can be manufactured.

Abstract: Recording methods, systems and media for recording and read-out with relatively low-power laser means to write digital data "bits" (as reflectance changes) for high density computer storage. One preferred medium comprises a disk support having an "anti-reflective" surface on which is laid a non-continuous "information layer" adapted to absorb recording radiation (from laser beam), and so "write" the bits, by "agglomerating" (coalescing).The information layer exhibits suprisingly high sensitivity, apt for low power recording, and extended archival stability; more suprising, it appears to be formed without any evidence of the usual ablation, "pit formation" or other deformation.

Abstract: A method for optically recording information on an optical information recording medium comprising a light transmitting substrate, a light absorptive layer overlaying the substrate to absorb a laser beam and a light reflective layer overlaying the light absorptive layer, which comprises energizing the light absorptive layer by a laser beam entered through the light transmitting substrate, and locally deforming, by the energy thereby generated by the light absorptive layer, a surface layer of the substrate adjacent to the light absorptive layer, to form optically readable pits in the surface layer of the substrate.

Abstract: An organic thin film formed of molecules of at least one dye compound selected from the compounds represented by the following general formulae: ##STR1## wherein X is a hydrogen atom, a methyl group, or a halogen atom, R.sup.1 is an electron attractive group substituted with a hydrophobic group having 12 or more carbon atoms, Z is either=0 or=NR.sup.2, and R.sup.2 is an electron attractive group or an electron attractive group substituted with an organic group having 1 to 50 carbon atoms; andR--(DS) (III)where R is an organic hydrophobic group having terminated with two long chain alkyl groups or an organic hydrophobic group having a steroid carbon skeleton, and DS is a dyestuff group having a dye skeleton of tetracyanoquino dimethane, N, N'-dicyanoquinonediimine, N-cyanoquinoneimine, benzoquinone, pheylenediamine, tetrathiafulvalne, tetraselenavalene, ferrocene, phthalocyanine, or porphyrin.

Abstract: An erasable optical disc medium on which information is recorded and read by using a laser beam, which comprises (i) a phase transition type information recording layer, (ii) an optical interference layer and (iii) an optical reflection layer, formed in this order on a transparent substrate, in such a state that a reflectance of the medium is higher before information is recorded and a reflectance of the recorded portions of the medium is lower after recording.

Abstract: An information recording medium of an air-sandwich sealed type is disclosed, which comprises a pair of disk-shaped substrate to form an inner space therebetween; an inner circumferential spacer and an outer circumferential spacer interposed between the pair of disk-shaped substrates; and a recording layer formed on the inner surface of at least one of the disk-shaped substrates, with an adhesive agent being applied to the surface of at least the inner circumferential spacer or the outer circumferential spacer in the form of a plurality of concentric adhesive layers, each of the concentric adhesive layers having at least one cut-away portion to which the adhesive agent is not applied to form a vent and an air passage between the surface of the inner circumferential space or the outer circumferential spacer and any of the substrates, the vent and the air passage capable of allowing the air to pass from the inner inner space formed by the disk-shaped substrates to the outside and vice versa, and the cut-away por

Abstract: Information on a spinning magneto-optic disk is overwritten by illuminating a spot on a track on the disk with an erasing beam in the presence of a biasing magnetic field, and illuminating another spot on the same track with a writing beam during the same revolution of the disk. The erasing beam and writing beam can be focused through the same lens. The erasing beam erases all bits to the same known value, so it is not necessary to control the writing beam according to the old values of the bits. Benefits include simpler control logic and less stringent positioning requirements than in the past.

Abstract: An optical disk structure for an erasable optical disk for use with an erasable optical disk drive using electron trapping optical memory media is disclosed in which several distinct layers in additon to the electron trapping optical memory media are utilized in order to minimize light scatter between adjacent tracks on the disk and to carry permanent format and guidance information for use in accomplishing the write, read and focusing and tracking functions of the erasable opticl disk drive with which the disk structures are utilized. The use of absorbing layers as part of the optical disk structure for attenuating reflections of light within the disk structure and eliminating the spreading of marks is also disclosed.

Abstract: An optical disk with a substrate made of glass at least partially has its inner and outer peripheral surfaces polished to surface roughness of 5 .mu.m or less so as to reduce the amount of glass powder generated from these surfaces and to thereby improve the yield.

Abstract: Erasable optical disk media basically comprise a double layer structure composed of a thermal expansion layer formed of an organic dye and a binder, and a retention layer of metal. In the recording process, the thermal expansion layer is heated to form a dome-like pit in the retention layer. The reproducing process is performed by reading differences in reflectivity from the pit and an area surrounding the pit. In the erasing process, the retention layer including the pit is heated to flatten the same under the tensile stress (residual stress) acting on the thermal expansion layer. The pit size is kept in a stable condition during the recording and reproducing processes, while the erasing can be performed completely without leaving partly erased traces. The erasable optical disk media of the foregoing construction are highly durable and resistant to heat.

Abstract: A recording and readout method for a multi-layer recording film including providing a multi-layer recording film comprising a laminate of plural recording films having a light absorption band in a predetermined wavelength region and having an intrinsic absorption peak; and supplying to the multi-layer recording film a light having a wavelength which is substantially the same as that of the absorption peak of each recording film to effect recording and readout; wherein provided that the light absorption band of the recording film having the absorption peak on the longer wavelength side selected from adjacent absorption peaks is present in a wave length region which is shorter than the absorption peak wavelength on the shorter wavelength side; the recording film having the absorption peak on the shorter wavelength side is caused to have an absorbance which is higher than the absorbance of the recording film having the absorption peak on the longer wavelength side at the absorption peak wavelength on the shorter

Abstract: An optical type information record carrier is disclosed which includes an arrangement wherein the depth of the guide grooves is selected to be about (2N+1).lambda./8n (N=1, 2, 3, . . . ) and the inclination angle of the wall surface of the carrier is steep enough to ensure that the information recording medium will not adhere to the wall surface of the guide grooves, or will only adhere very weakly if it does adhere. Thermal conduction at the wall surface of the guide grooves is prevented so that extension of the recording bits is restricted.

Abstract: A method of and a photomask for manufacturing an optical memory element. The manufacturing method includes the steps of: subjecting a positive type photoresist coated on a glass substrate to exposure by using the photomask capable of irradiating light onto a portion of the photoresist other than the remaining portion for forming pits of the glass substrate such that the portion of the photoresist is solubilized against developing solution; developing the photoresist by using the developing solution so as to remove the portion of the photoresist; and etching the glass substrate so as to directly form, as convex portions, the pits on a surface of the glass substrate.

Abstract: A thin film is formed on a plastic substrate that is preformed with recording tracks, either continuous or discontinuous, formed of a metal containing film on a thermoplastic substrate. Individually-identifiable recording elements arranged in rows are preferred. Initial reflection of the recording elements are reduced by etching or microscopically roughing the surface to produce discontinuities with dimensions less than one wavelength of the light being used to record on and read from the media. The rough surface may be created on the plastic before the application of the metallic film or the film itself may be roughened after application to the plastic. The resulting micromirrors can have about equal initial reflectivity and absorption of about fifty percent with little or no transmission. The location of the individual recording elements can be determined prior to recording and used as a gauge to permit compensation for changes in the scanning velocity of the reading or writing beam.

Abstract: This invention is directed to the storing of digital information. This storage system comprises a number of layers of transparent or translucent material. In each layer there is a chemical or chemicals subject to change by being contacted with different electromagnetic wave lengths. For example, if there be eight layers then the chemical or chemicals in any layer is subject to be changed by an electromagnetic radiation of a wave length different than for any of the other seven layers. In this manner, with eight layers it is possible to have an eight bit byte. Actually, under premutations and combinations it is possible to have as many as eight bit bytes from the eight layers. It is conceivable that there may be more than eight layers such as sixteen layers of thirty-two layers. There is the possibility of storing large amounts of information in a small volume.

Abstract: An optical information recording medium is composed of a substrate and a recording layer, formed thereon, which recording layer causes the reversible phase change by the application of an electromagnetic wave thereto, and comprises a phase-changeable type alloy with the composition of (XYZ.sub.2).sub.1-x M.sub.x, wherein X is an element of the group Ib, Y is an element of the group Va, Z is an element of the group VIa, M is an element selected from the group consisting of Sb, Bi, In, Al and Ga, and 0<x<1.

Abstract: A metal reflecting layer of an aluminum or silver alloy containing gold has a lower thermal conductivity than aluminum or silver and gold while maintaining a high reflectivity, and thus an optical recording medium, particularly a magneto-optical recording medium, having a high recording sensitivity and a C/N ratio, as well as an improved durability, can be provided. The content of Au in the Al alloy is 0.5-20 at % and that in the silver alloy is 0.5-30 at %. Preferably, at least one of the group consisting of titanium, tantalum, zirconium and yittrium is added to an alloy of Al or Ag with Au, and the content of at least one of the group consisting of titanium, tantalum, zirconium and yittrium is preferably 0.3-5.0 at % in an Al-Au alloy and 0.3-12.0 at % in an Ag-Au alloy. More preferably, the total content of Au and at least one of the group consisting of titanium, tantalum, zirconium and yittrium is 1.0-15 at %.

Abstract: A novel optical media is provided for use in an optical recording and reproducing system. The optical media comprises a tuned multilayer optical structure employing an archival thin film absorber having a relatively high melting point, such as gold, along with an in-contact overcoat. The characteristics of the media are chosen so as to permit use of a specially chosen hole-forming data recording mechanism which permits recording optically detectable data in the media without requiring heating of the absorber material to its bulk melting point, and also without requiring ablation of the absorber material, whereby compatibility with the in-contact overcoat is also achieved.

Abstract: An optical storage medium is disclosed. In a preferred embodiment a substrate is provided with an expansion layer. A retention layer is provided opposite the substrate. A liquid reflective layer is provided adjacent the retention layer, either adjacent to or opposite the expansion layer. The reflective layer is enclosed by a protective layer. Improved expansion and retention layers are also disclosed.

Abstract: An optical information recording medium comprising a light transmitting substrate, a light absorptive layer overlaying the substrate to absorb a laser beam and a light reflective layer overlaying the light absorptive layer, wherein an optical parameter represented by .rho.=n.sub.abs d.sub.abs /.lambda. where n.sub.abs is the real part of the complex refractive index of the light absorptive layer, d.sub.abs is the thickness of the light absorptive layer and .lambda. is the wavelength of a reading laser beam, is 0.05.ltoreq..rho..ltoreq.0.6, and the imaginary part k.sub.abs of the complex refractive index of the light absorptive layer is at most 0.3.

Abstract: Recordable/erasable optical storage media are disclosed. The medium of the present invention generally comprises a rigid substrate, an expansion layer, a retention layer, and a dual-metal reflective layer. A single, active layer may be substituted for the expansion and retention layers. A protective layer may or may not be present. The dual-metal reflective layer comprises a first metal sublayer and a second metal sublayer with a graded first metal/second metal alloy at the interface of the first metal sublayer and the second metal sublayer. Methods for applying the dual-metal reflective layer to a polymer-coated substrate and substrates produced by such methods are also provided.

Abstract: An improvement is disclosed relating to optical data storage media having two thermo-optically active layers which absorb light at distinct wavelengths--an expansion layer in which data appear as bulges formed upon the absorption of light, and a retention layer which fixes such bulges in place until it is selectively heated to a rubbery state permitting relaxation of the expansion layer and the consequent disappearance of the bulges. In accordance with the improvement, the retention layer is modified so that it absorbs a controlled amount of light at the wavelength which is absorbed by the expansion layer, with the result that it absorbs light at both wavelengths rather than just one. Direct heating of both layers by light absorption during recordation, and accordingly a faster recordation response, are thus achieved.

Abstract: The invention provides an optical recording medium and a method of recording, reading, and erasing information to an optical recording medium, where information is recorded, read, and erased to the recording medium by applying beams projected from a light source capable of varying wavelength of beams. The recording medium contains at least two kinds of organic compounds each presenting photochromic phenomenon and being dispersed in binder. By projecting beams onto the optical recording medium, recording, reading, and erasure of information making use of a photochromic phenomenon can be executed independently against each organic compound dispersed in the recording medium. As a result, the optical recording medium promotes to increase the information recording density in proportion to the number of the kind of organic compounds.

Abstract: A photo-mask and a method of manufacturing a photo-mask, which includes the steps of applying a resist film onto a substrate of quartz, glass and the like, subjecting the resist film to light exposure and development to form a fine resist pattern, etching the mask substrate covered by the fine resist pattern causing a non-light transmitting thin film of Cr, Ta, etc. to adhere thereon by vapor deposition, sputtering and the like, and removing the thin film on the resist pattern together with the resist film, thereby to form the photo-mask.

Abstract: An optical information recording medium comprising a light transmitting substrate having a spiral pregroove formed on its surface, a light absorptive layer of a coloring matter formed on the substrate directly or with other layer interposed therebetween, and a light reflective layer made of a metal film formed on the light absorptive layer directly or with other layer interposed therebetween, wherein .DELTA.S.ltoreq.0.3 wherein .DELTA.S is the optical phase difference represented by .DELTA.S=2d.sub.sub {n.sub.sub -n.sub.abs (1-d.sub.abs /d.sub.sub)}/.lambda. wherein d.sub.sub is the depth of the layer boundary on the substrate side of the light absorptive layer at the portion corresponding to the pregroove, d.sub.abs is the depth of the layer boundary on the light absorptive layer side of the light reflective layer at the portion corresponding to the pregroove, n.sub.

Abstract: Recordable/erasable optical storage media are disclosed. More particularly, it provides a method and apparatus for recording and erasing information on an optical storage medium. The medium of the present invention generally includes a rigid substrate and an active region or layer adjacent to the substrate. The active region is a single polymer layer that functions as both an expansion layer and a retention layer. Reflective and protective layers may or may not be present. Additionally, methods for writing and erasing on these media are described.

Abstract: An optical disk is provided with a protective layer which is an adhesive which is non-tacky at room temperature in the case of a one sided disk; and which is useful as a tacky adhesive at room temperature in the case of a two sided disk made from two one-sided disks bonded to one another.

Abstract: Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. The thin memory film preferably includes not more than 60 atom % of Gallium (Ga) and not less than 40 atom % of Antimony (Sb).

Abstract: There is disclosed an optical disk having an optical reflectivity of 70% or above which comprises a substrate made of a thermoplastic saturated norbornene type polymer having a glass transition temperature of 100.degree. C. or above and a light reflecting layer formed by laminating, on said substrate, a multi-layer film constituted of at least one compound selected from the group consisting of metallic oxides and metallic fluorides.

Abstract: An optical type information recording medium has guide grooves for tracking formed in a concentric or spiral shape at a predetermined pitch; and a pre-format pit formed approximately midway between the guide grooves in the normal direction thereof and recording at least address information. The optical type information recording medium is constructed such that the predetermined pitch is a value ranged from 1.4 .mu.m to 2.0 .mu.m, and the depth of the pre-format pit is a value ranged from 0.46 .lambda./n to 0.58 .lambda./n where n shows the refractive index of a substrate of the medium and .lambda.

Abstract: An optical disk substrate having a foreign-substances index of not more than 1.times.10.sup.5 .mu.m.sup.2 /g, an optical information-storage medium wherein the substrate has an information-recording layer, and a propocess and an apparatus for manufacturing the optical disk substrate.

Abstract: In an information recording medium having laminated two disc substrates by an adhesive, each disc substrate comprising a substrate and a recording layer, so that the recording layers are disposed opposite to each other, this invention provides an information recording medium wherein said adhesive is a hot melt adhesive having a softening point of 130.degree. C. or more. Said information recording medium forms no deviation betweeen two laminated disc substrates thereof and decreased deformation such as warpage even when exposed to an atmosphere at high temperature and humidity for a long time.

Abstract: An optical recording medium, which is used as an optical disc, optical card or the like for optically recording, reproducing, erasing and the like, includes a center substrate having formed on at least one side thereof recesses and/or protrusions. Recording films are formed on both sides thereof and transparent protective plates bonded to these recording films respectively. This arrangement substantially eliminates warping of the substrates constituting the optical recording medium and exfoliation of substrates or the like even when the optical recording medium is subjected to sudden changes in temperature. This optical recording medium demonstrates enhanced optical performance and protective effect. The selecting of the transparent protective plate is simplified because the forming recesses and/or protrusions is not a factor. By producing an optical recording medium utilizing the above features, the carrier-to-noise ratio and isotropy of the medium is improved.

Abstract: An optical information signal record medium which comprises a substance of a desired form having information signals encoded on at least one side thereof, a reflection thin layer of a Cu alloy, and a protective layer formed on the substrate in this order. The reflection thin layer is made of an alloy such as a Cu-Ni alloy, a Cu-Al alloy or a Cu-Ni-Al alloy each having a defined composition.

Abstract: Recording and erasing optical information can be done by using an alloy film capable of forming two stable crystalline states differing in crystal texture and optical characteristics by being irradiated with optical energies under different conditions. The memory film includes 35-45 atom % of indium (In) and 55-65 atom % of antimony (Sb). The memory film may include an additional element M selected from the group consisting of Al, Si, P, S, Zn, Ga, Ge, As, Se, Ag, Cd, Sn, Te, Tl, Pb, Bi, and a combination of these elements, the composition of the memory film being expressed by the formula (In.sub.x Sb.sub.1-x).sub.1-y M.sub.y.