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Information × Registration Number 0218U007171, 0118U004397 , R & D reports Title Superconductor nanocomposites - ferromagnetic semi-metal as the newest functional materials for microwave radiation registration popup.stage_title Head Tarenkov Vladimir Yuriyevich, Registration Date 20-12-2018 Organization Donetsk Institute of Physics @ Engineering named after O.O.Galkin NAS of Ukraine popup.description2 The purpose of the project: Creation of the newest functional material on the basis of nanocomposite superconductor-ferromagnetic material for the registration of ultrahigh-frequency radiation. Objects of research: The characteristics of nanocomposite, a mechanical mixture of granules of high-temperature superconductor Bi2223 (Bi2Sr2Ca2Cu3O6 + x) and lanthanum manganite La0.65Ca0.35MnO3, were studied. The peculiarity of the composite ingredients is the size of the granules. Granules of bismuth metal oxide had a size d = 5-10 microns, and a manganite d = 15-30 nm. This ratio of the size of the granules in the composite leads to the fact that even with 20-25 volumes percent of manganite in the composite, the percolation cluster along the high conductive component Bi2223 turns out to be torn. Samples of a composite with different volumetric contents of the component are plates S = 1 x 0.1 x 10 mm3, obtained by a one-sided compression under pressure of 50-60 kbar. Methods of research: Strength and potential silver contacts with low transient resistance allowed to connect samples in a four-probe circuit. Measurements of resistive transition of samples of composite with different volumetric contents of a magnet are carried out. The dependence of the specific resistance on the concentration of magnetic nanoparticles indicates the activation character of the conductivity of the composite. The course of the temperature dependence of the resistance of the composite shows a successive transition to the superconducting state of granules of bismuth metal oxide with TS = 110 K and with subsequent decrease of the temperature of the transition of the whole sample into a phase-coherent state. The superconducting state of the composite was observed at T = 4.2 K for concentrations of manganite 25-30% volume. At higher concentrations of manganite, the samples had residual resistance. Such a character of the temperature dependence of the resistance of the composite indicates the formation of percolation tapes with the contact structure of the superconductor - manganite - the superconductor. Such a contact structure, which occurs in composite samples, forms the so-called Josephson medium, the characteristics of which allow to efficiently process high-frequency signals in a wide frequency range due to the magnitude of the energy gap of the superconductor. Scientific significance: The results obtained are important from the point of view of the fundamental knowledge of the mechanism that causes an unusual interaction in the effect of the proximity of two fundamentally different interactions of superconductivity and magnetism. The peculiarities of the mechanism of transformation of the Cooper pairs state with the d-symmetry of the ordering parameter observed in the VTNP materials in the p-symmetry of the Cooper pairs formed in manganite as a result of the proximity effect were revealed in the composite formed from a high-temperature superconductor and a magnetic metal (manganites of lanthanum). The generated composite medium with a percale character of the passage of the current will have the properties of a lattice of Josephson contacts with a large number of elements. Practical significance: Volt ampere characteristics of samples of studied nanocomposites have nonlinear dependence and surplus current, which allows them to be used as a functional material for recording ultrahigh-frequency radiation in a wide range of capacities and frequencies. Product Description popup.authors Білоголовський Михайло Олександрович Болясова Ольга Олександрівна Криворучко Володимир Миколайович popup.nrat_date 2020-04-02 Close