Abstract: The use of vanadium on the tetrahedral site of a garnet material together with a suitable charge compensating ion, such as Ca.sup.2+, results in advantageous materials. In particular, very high Curie temperatures, e.g., up to 524 degrees C., in films capable of supporting 1 .mu.m-sized bubble domains, are observed. Additionally, the change of collapse field with temperatures for magnetic bubble domains in the garnet material is linear and closely parallels over a wide temperature range the change of bubble controlling static field of permanent magnets typically employed in magnetic bubble devices. A substantially constant bubble size is maintainable over a wide temperature range. The desired garnet compositions are produced advantageously from a melt containing a suitable ratio of vanadium to calcium.

Abstract: A method of implanting a magnetic garnet film with ions is disclosed in which a covering film is provided on a monocrystalline magnetic garnet film for magnetic bubbles, and hydrogen ions are implanted in a desired portion of a surface region in the magnetic garnet film through the covering film. According to this method, it is possible to form an ion-implanted layer in which the ion concentration distribution in the direction of depth is uniform, and moreover the inplane anisotropy field in the ion-implanted layer decreases only a little with time in an annealing process.

Abstract: Magnetic device having a monocrystalline substrate bearing a magnetic layer, said substrate having a composition on the basis of rare earth metal gallium garnet of the general formula ##STR1## wherein A=gadolinium and/or samarium and/or neodym and/or yttriumB=calcium and/or strontiumC=magnesiumD=zirconium and/or tin andO<x.ltoreq.0.7; O<y.ltoreq.0.7 and x+y.ltoreq.0.8.

Abstract: A device for propagating magnetic domains includes a monocrystalline nonmagnetic substrate of a rare earth gallium garnet bearing a layer of an iron garnet capable of supporting local enclosed magnetic domains. The iron garnet layer is grown in compression on a (100) face of the nonmagnetic substrate. The iron garnet comprises manganese in part of the iron sites of its crystal lattice, and comprises yttrium and at least one representative selected from the group comprising bismuth and the rare earth metals in the dodecahedral lattice sites. Such a magnetic garnet has a very high uniaxial anisotropy and a high domain mobility. These properties make the device extremely suitable for propagating submicron magnetic domains having diameters as small as 0.4 .mu.m.

Abstract: A device for propagating magnetic domains, comprising a monocrystalline nonmagnetic substrate of a material having a garnet structure, and a layer of an iron garnet grown epitaxially on the nonmagnetic substrate. In the dodecahedral lattice sites, the iron garnet comprises at least a bismuth ion and a rare-earth ion selected from the group consisting of lutetium, thulium, and ytterbium. Such a magnetic garnet combines very high uniaxial anisotropy with a high domain mobility, which properties make the device extremely suitable for the propagation of magnetic domains having diameters from approximately 1 to approximately 2 .mu.m under the influence of comparatively low driving fields.

Abstract: Certain Tm-containing iron garnet compositions provide layers having desirably low values of temperature coefficient of bubble collapse field and permit the fabrication of 1.2 .mu.m diameter magnetic bubble devices. The compositions, based on Tm-substitution on dodecahedral sites of [(La,Bi),(Sm,Eu),R].sub.3 (Fe,Al,Ga).sub.5 O.sub.12, are grown by liquid phase epitaxy onto suitable substrates. Bubble devices that incorporate the layers find applications in high density information storage.

Abstract: Yttrium-iron magnetic domain materials having bismuth ions on dodecahedral sites are suitable for the manufacture of high-density, high-speed magnetic domain devices for operation at high and especially at very low temperatures. In these devices magnetic domain velocity is greater than 2000 centimeters per second per oersted, and magnetic domain diameter is less than 3 micrometers. A specified operational temperature range may extend from -150 to 150 degrees C.; accordingly, such devices are particularly suitable for operation aboard satellites, e.g., in satellite communications systems.

Abstract: A magnetic structure in which magnetic domains can propagate. The structure comprises a monocrystalline gallium garnet substrate having a surface which is substantially parallel to a (100) crystal plane and on which a layer of rare-earth iron garnet, having a partial substitution of maganese ions in iron sites, is grown in compression. By using a substrate material having a lattice constant between 12.23 and 12.38 .ANG., the compression of a epilayer having certain desired magnetic properties can be adjusted by adjusting the incorporation of lutetium and yttrium ions in the epilayer, without adversely affecting magnetic properties of the layer.

Abstract: With the fabrication of a substrate material in the form of alkaline-earth gallate single crystals it has become possible to grow monocrystalline barium hexaferrite layers of high quality. These thin barium hexaferrite layers on the alkaline-earth gallate substrates are extremely suited as magnetic devices because of their very high uniaxial anisotropy and their small line width. Such magnetic devices can be used for passive microwave components, e.g. as resonance isolators or filters in the centimeter wavelength range, or as components in information storage technology, e.g. in magnetic cylindrical domain devices, especially in the field of very small (submicron) cylindrical domains.

Abstract: Devices based on epitaxial garnet layers that exhibit a high magnetic anisotropy are disclosed. These garnet layers are produced by introducing a Co.sup.2+ or a species with 1, 2, 4, or 5 electrons in a 4d or a 5d electron orbital in the octahedral site of the garnet in conjunction with a typical anisotropy producing combination on the dodecahedral site. The contribution to magnetic anisotropy due to the typical combination on the dodecahedral site and the appropriate ion in an octahedral site is complementary.

Abstract: A magnetic garnet film for a magnetic bubble memory device in which parts of rare earth element and iron are replaced by predetermined quantities of Gd and Ge, respectively. The garnet film exhibits very small temperature-dependency of the bubble collapse field as well as high Curie temperature, whereby magnetic bubbles of very small diameter can be sustained and controlled with stability over a wide temperature range.

Abstract: Devices based on epitaxial garnet layers which exhibit a substantial contribution to the magnetic anisotropy other than that attributable to the presence of magnetic rare earth ions are disclosed. These garnet layers are produced by introducing Co.sup.2+ or a species with 1, 2, 4, or 5 electrons in a 4d or 5d electronic orbital in the octahedral site of the garnet. It is possible to produce epitaxial garnets having low damping constants, as determined by resonance line widths on the order of 100 Oe, and K.sub.u 's on the order of 300,000 ergs/cm.sup.3.

Abstract: A novel non-magnetic monocrystalline garnet substrate material in the form of calcium--gallium-germanium garnet. Single crystals of calcium-gallium-germanium garnet can be grown at mush lower temperatures by means of the Czocharalski method than single crystals of the conventional rare earth-gallium garnets. These single crystals are very suitable to epitaxially grow bubble domain films thereon, in particular films on the basis of Lu.sub.3 Fe.sub.5 O.sub.12.

Abstract: A garnet film for a magnetic bubble domain device which comprises a predetermined quantity of Gd and a predetermined quantity of Ga.The garnet film has a temperature coefficient of not more than 0.2%/.degree.C. in respect of the bubble collapse field owing to the addition of Gd and Ga and is suitable for substaining small magnetic bubbles of a diameter of less than 2.5 .mu.m.

Abstract: In the preferred embodiment, a monocrystalline film of substituted yttrium iron garnet (YIG) deposited on a <11> oriented gadolinium gallium garnet (GGG) substrate is formulated so that the temperature variation of the ferromagnetic resonance frequency of the film has an ordinary minimum. For a range of temperature variations about the temperature at which the minimum occurs, therefore, the resonance frequency of the film is relatively insensitive to variations in temperature. This minimum is believed to occur where the temperature variations of the demagnetizing effect and the temperature variations of anisotropy effects more or less counterbalance each other. The counter-balancing effects are brought within range of each other primarily by the substitution of gallium or aluminum for iron and substitution of lanthanum for yttrium in the substituted YIG. Gallium or aluminum reduces the temperature drift of the saturation magnetization. Lanthanum adjusts the misfit stress and thus the anisotropy effects.

Abstract: The magnetic bias field required to collapse magnetic domains in an epitaxial liquid phase grown garnet is reduced by a method of depositing a layer of a suitable element, e.g. gallium or chromium, on the surface of the garnet after growth and then heating the garnet. The suitability of the element depends on its atomic diameter and affinity for oxygen.Propagation paths for bubbles in a magnetic bubble memory are defined by treating a garnet except where the propagation paths are required, by the method.

Abstract: A ferrite material has been found that is useful for a biasing magnet whose magnetic field stabilizes single wall magnetic domains. The strong temperature dependence of the ferrite's magnetic field makes the ferrite especially useful when used with magnetic materials which require a highly temperature dependent magnetic field to maintain a constant domain or bubble size. The ferrite composition is represented by the formula NiFe.sub.(1+x) Cr.sub.(1-x) O.sub.4, x is in the range between 0.04 and 0.18, and 1 percent to 10 percent, by weight, additional material selected from the group consisting of zirconium oxide, thorium oxide and hafnium oxide.

Abstract: The discovery of a magnetoresistive effect in oriented, crystalline, semiconducting iron garnet materials is used to design devices which detect the presence or orientation of magnetic fields. The principal measure of this effect is that the resistance between two electrodes (12) on the garnet body (11) varies as an imposed magnetic field (14, 15) produces a change in the direction of the magnetization of the body (11). This effect is useful when the garnet is so constituted as to possess a resistivity from 10.sup.3 to 10.sup.7 ohm-centimeters. Also, the anisotropy field of the garnet body must be comparable to less than the magnitude of the magnetic field to be detected. One aspect of particular utility for magnetic "bubble" detectors (in magnetic bubble memories) is the isotropic character of the resistance when the magnetization is varied in the (111) plane but the significant change of resistance when the magnetization is moved to the [111] direction.

Abstract: Input swap transfer/replicate gate and output replicate gate for use in a magnetic bubble memory arrangement between the bubble storage loops and the input and output sections respectively on opposite sides thereof. The input swap transfer/replicate gate and the output replicate gate are of double level construction, each type of gate including a hairpin element at the first level and mounted on a planar layer of bubble-supporting magnetic material on which bubble propagation elements of magnetically soft material are disposed. The bubble propagation elements are arranged to form propagation paths defining a bubble input section, a bubble output section, and a plurality of closed storage loops defining a bubble storage section interposed between the input and output bubble sections. The second levels of the swap transfer/replicate gate and output replicate gate are situated at the input and output ends of the storage loops, forming the opposite bights of the loop.

Abstract: A magnetic bubble storage device is formed with a major-minor loop organization wherein the bit pitch in at least a part of a first region of the major loop other than a second region where the major loop and the minor loops are connected is larger than the bit pitch in the second region. This permits the realization of a pattern arrangement with a broader operating margin and also facilitates the addition of redundant minor loops.

Abstract: In a gate arrangement, an information input bubble is deflected from an input path into an output path when moving in proximity of a control bubble on a control path in the interaction zone. T- and I-shaped permalloy elements of the control path pattern are so disposed in the interaction zone to create a very stable control bubble position. At the intersection of the output and input paths the latter is situated at most at three times the nominal bubble diameter from the stable control bubble position. Past the intersection, the input path is as close as one bubble diameter to the control bubble so that the information bubble is necessarily deflected. With the gate layout described a bias margin as high as 11,5% is obtained.

Abstract: The temperature variation of the bubble collapse field of a class of garnet magnetic bubble layer materials is selected by selection of the ratio PbO to B.sub.2 O.sub.3 in the flux from which the layer is grown. This permits the growth of layers, whose temperature dependence of critical magnetic properties more closely match the temperature dependence of bias magnet materials, resulting in extended operating temperature range and/or wider operating margins (with attendant improvement in manufacturing yield). Layer growth at higher ratios of PbO to B.sub.2 O.sub.3 produces films of higher rate of change of bubble collapse field with temperature.

Abstract: Magnetic bubble domain memory circuit in which magnetizable overlay patterns of magnetically soft material, e.g. permalloy, are provided as bubble propagation elements on a bubble-supporting magnetic layer to define major and minor bubble propagation paths. The major bubble propagation paths provide interchangeable bubble input and output sections, and the minor bubble propagation paths are in the form of closed storage loops providing a bubble storage section comprising first and second pairs of blocks. Bubble generators are provided for each of the blocks included in the first and second pairs thereof comprising the bubble storage section, along with first and second detectors and input/output tracks of bubble propagation elements associated with the respective pairs of blocks of storage loops. Swap transfer/replicate gates are disposed between the input/output tracks and each of the storage loops included in the blocks of storage loops.

Abstract: Magnetic bubble domain memory circuit in which magnetizable overlay patterns of magnetically soft material, e.g. permalloy, are provided as bubble propagation elements on a bubble-supporting magnetic layer to define major and minor bubble propagation paths. The bubble propagation elements are arranged to form major propagation paths defining a bubble input section and a bubble output section respectively. A plurality of minor propagation paths in the form of closed storage loops defining a bubble storage section are disposed between the input and output bubble sections, being arranged in even and odd blocks of minor propagation paths. Input swap transfer gates and output replicate gates are provided between the bubble storage loops and the input and output sections respectively. The input swap transfer gates and the output replicate gates are of double level construction, each type of gate including a hairpin element at the first level and a 90.degree.

Abstract: A device for reading information-representing magnetization patterns by means of a magneto-resistive element. The magneto-resistive element is in magnetic flux coupling with a plurality of magnetization patterns simultaneously. A desired portion of the element is selected for reading by influencing such portion by the external magnetic field of a magnetic bubble domain. Information positions can be read in sequence by moving the bubble domain along magneto-resistive element.

Abstract: A magnetic bubble device comprising a non-magnetic substrate layer, and a sequence of magnetic layers joined to each other and to the magnetic substrate layer, e.g. by epitaxial growing of crystalline layers, whereby at least two of the magnetic layers may accommodate magnetic bubbles which are stably joined through an interlayer magnetic compensation wall, or by an essentially finite potential barrier.

Abstract: A method for detecting the wall state of a soft bubble based upon the collapse characteristics of the bubble domain on a layer of bubble domain supporting material is described. The method includes the step of exchange coupling a magnetic layer, for example, an ion-implanted layer, to the bubble supporting layer. An in-plane field is applied to the bubble supporting layer when Bloch lines are present in the bubble domains. The bias field and the pulse field are set at a level to form a range of pulse widths which are suitable for the discrimination of soft bubble domains having different wall states. A pulse is then applied for a time sufficient to collapse only the S=1 bubble and not the S=0 bubble. Thereby this method distinguishes S=0 bubbles having one pair of winding Bloch lines from S=1 bubbles having one pair of unwinding Bloch lines. This method also distinguishes S=1 bubbles having a clockwise chirality from S=1 bubbles having a counterclockwise chirality.

Abstract: A magnetic bubble domain structure and method of making comprising a film of a nickel-iron alloy of 80 to 83.5% nickel content and substantially zero constant of magnetostriction formed by vapor deposition of the alloy onto a flat substrate at a substrate temperature in the range of room temperature to 200.degree. C. at an angle of incidence of approximately 60.degree. to a film thickness of 0.2.mu.m to 3.0.mu.m, the film being immersed in a magnetic field perpendicular to the film and of 1600 to 2400 oersteds intensity.

Abstract: A low power, conductor-access, bubble memory is realized with a single level of metallization for providing the requisite propagation fields. Sets of apertures in the conducting layer define bubble paths, and permalloy elements aligned with the apertures overlie the conducting layer at end portions and contact the exposed bubble layer at midportions. Current flow is established transverse to the bubble paths.

Abstract: Members of a class of garnet compositions of particular crystallographic orientation are usefully incorporated in magnetic memory devices which depend for their operation on the positioning of single wall domains ("bubbles"). Such compositions, ordinarily in the form of a supported layer defining a (110) orientation, manifest high limiting bubble velocity, thereby making possible high record and retrieval rates. Compositions invariably contain some lanthanum in the dodecahedral site. Increased limiting velocity is attributed to in-plane anisotropy, in turn, dependent upon partial lanthanum occupation. Depending upon composition, required unique easy direction out of the plane may be as-grown, stress induced, or a combination. Appropriate garnet substrates of required lattice parameters are described.

Abstract: A magnetic structure having a high magnetic bubble mobility which has the property that magnetic bubbles can be transported in it at very high velocities while using comparatively weak driving fields, comprising a substrate having a (110) oriented deposition surface on which a layer of rare earth -- iron garnet with a substitution of Mn.sup.3+ in iron lattice sites has been grown in compression in such a manner that the layer of rare earth-iron garnet has an orthorhombic anisotropy.

Abstract: A magnetic bubble information writing device in which a conductor loop is disposed on the magnetic bubble propagation circuit and in which magnetic bubbles are generated by sending pulse current through the conductor loop, the device having a means which after having sent the bubble generating pulse current through the conductor loop, sends pulse current for annihilating stray bubbles through the same, the stray bubble annihilating pulse current having a polarity opposite to that of the bubble generating pulse current.

Abstract: This bubble domain sensor is capable of sensing the presence or absence of a bubble at a predetermined location within bubble supporting material regardless of whether the bubble is stationary or moving through that location. A magnetostrictive material layer, such as a thin film having an area approximately equal to the area of a bubble domain, is positioned with respect to the bubble material such that it is magnetically influenced by the closure field of a bubble at the predetermined location. A conductor, such as a strip conductor, is positioned in contact with the magnetostrictive material. A sonic device launches sonic wave pulses which pass in the vicinity of the magnetostrictive material layer. The sonic wave pulse stresses the magnetostrictive material, and when the magnetostrictive material is magnetically influenced by a bubble, the stress changes or rotates its magnetization thereby inducing an electric signal in the conductor.

Abstract: An improved ion implanted propagation structure for movement of magnetic bubble domains in a storage medium which comprises an additional magnetic layer capable of ion implantation in combination with a bubble domain storage layer in which the bubble domains exist and are moved by the ion implanted layer in response to the reorientation of a magnetic field in the plane of the ion implanted layer. The ion implanted layer (drive layer) can be in intimate contact with the storage layer and exchange coupled thereto, or can be separated from the storage layer by a non-magnetic spacer. The ion implanted layer can comprise different geometry propagation elements and its thickness, 4.pi.M, and other magnetic properties are generally selected to provide flux matching of a charged wall in the ion implanted layer with the flux emanating from the bubble domains to be moved. The charged wall is coupled to the bubble domain by exchange coupling and/or magnetostatic coupling. SUBACKGROUND OF THE INVENTION1.

Abstract: The critical velocity at which magnetic bubbles can propagate within a matic material is increased by establishing an easy axis of magnetization within the material. This axis is either growth-induced or strain-induced. In one embodiment, the material has a curvature imparted to it which places it under a uniaxial strain and this induces the magnetic easy axis.