2024, Charikova, T. B., Devyaterikov, D. I., Neverov, V. N., Popov, M. R., Ivanov, A. A., Иванов, Андрей Анатольевич

2020, Kuznetsov, A. V., Churkin, O. A., Ivanov, A. A., Popov, V. V., Alekseev, P. A., Menushenkov, A. P., Кузнецов, Алексей Владимирович, Чуркин, Олег Алексеевич, Иванов, Андрей Анатольевич, Попов, Виктор Владимирович, Алексеев, Павел Александрович, Менушенков, Алексей Павлович

© 2019We present the study of magnetic susceptibility of pyrochlores Gd2Ti2O7, Dy2Ti2O7 and Tb2Ti2O7 which belong to frustrated magnets. The temperature dependence of the susceptibility χ(T) of powder samples was measured in the temperature range from 4.2 to 300 K and analyzed in the framework of mean field approximation taking into account both crystal field effects and anisotropy of the exchange interaction. We developed a simple approach allowing us to estimate interaction energies of magnetic ions from χ(T) dependences and data on wave functions of the crystal-field states of the ions using a minimum number of fitting parameters. We revealed a strong anisotropy of the exchange interaction in the paramagnetic state of Gd2Ti2O7 and obtained nearest-neighbor effective bond energies of the magnetic ions in Tb2Ti2O7 and Dy2Ti2O7 which are in good agreement with the temperatures of formation of the spin-ice state in these compounds.

2019, Popov, M. R., Klepikova, A. S., Shelushinina, N. G., Charikova, T. B., Ivanov, A. A., Иванов, Андрей Анатольевич

© 2019 Elsevier B.V.The in-plane and out-of-plane carrier transport and the motion of a vortex system in the high quality epitaxial films with different orientation of the c axis of electron-doped superconductors Nd2−xCexCuO4+δ in crossed magnetic and electrical fields were investigated. The activated behavior of the vortex through the barrier at low temperature between CuO2 - planes due to intrinsic interlayer pinning is found as a function of the magnetic field depending on the anisotropy resistivity coefficient.

2020, Tulina, N. A., Borisenko, I. Y., Shmytko, I. M., Rossolenko, A. N., Ivanov, A. A., Иванов, Андрей Анатольевич

© 2020, Springer Science+Business Media, LLC, part of Springer Nature.We have been studying the dynamic effects of bipolar resistive switching (BERS) in memristive planar heterostructures based on c-oriented epitaxial films of the high-temperature superconductor YBa2Cu3O7 (YBCO). We have been observing the suppression of the memristive properties of the structures under sinusoidal and pulse loads and the nucleation and the evolution of the regions of current density and electric field in the structures under study. We found that the limiting frequencies of a sinusoidal type load for observing the switching effect are frequencies of about 104 Hz. It has been shown that the percolation channel is formed by the appearance of electric field domains in which the electric field threshold is reached. The switchings are controlled by two processes, with time t < ms and a longer time of the order of a few seconds. Possible physical models of the observed phenomena are being discussed.

2023, Popov, V. V., Menushenkov, A. P., Dubyago, F. E., Yastrebtsev, A. A., Ivanov, A. A., Rudakov, S. G., Попов, Виктор Владимирович, Менушенков, Алексей Павлович, Ястребцев, Алексей Алексеевич, Иванов, Андрей Анатольевич, Рудаков, Сергей Геннадьевич

2025, Popov, V. V., Markova, E. B., Zubavichus, Y. V., Menushenkov, A. P., Yastrebtsev, A. A., Ivanov, A. A., Gaynanov, B. R., Berdnikova, M. M., Pisarev, A. A., Попов, Виктор Владимирович, Менушенков, Алексей Павлович, Ястребцев, Алексей Алексеевич, Иванов, Андрей Анатольевич, Гайнанов, Булат Радикович, Бердникова, Мария Михайловна, Писарев, Александр Александрович

2024, Sviridova, A. A., Shchekin, A. S., Petrovskiy, V. N., Ivanov, A. A., Berdnikova, M. M., Свиридова, Ангелина Алексеевна, Щекин, Александр Сергеевич, Иванов, Андрей Анатольевич, Бердникова, Мария Михайловна, Петровский, Виктор Николаевич

2019, Popov, M. R., Klepikova, A. S., Charikova, T. B., Talantsev, E. F., Ivanov, A. A., Иванов, Андрей Анатольевич

© 2019 IOP Publishing Ltd.In this paper we present the experimental results on the temperature dependences of c-axis resistivity, (T), for epitaxial films of n-type superconductor Nd2-xCexCuO4+δ deposited on (110) SrTiO3 single crystal substrate in a wide range of Ce content from lightly to heavily substitution regions () under an optimal annealing. Alternative empirical models were used for a description of the observed semiconductor-like dependence. An excellent quantitative depiction of the experimental dependences turned out to be possible for all investigated samples in a model of natural superlattice with temperature-dependent barrier height.

2020, Il'in, A. I., Trofimov, O. V., Ivanov, A. A., Иванов, Андрей Анатольевич

© 2020, Pleiades Publishing, Ltd.Abstract: A correlation was found between the endset temperature of the superconducting transition T(R = 0) of YBa2Cu3O7 – x films 100–200 nm thick, obtained by pulsed laser deposition on SrTiO3(100) substrates with a temperature of ~740°C, and the regimes of high-speed filtering of the erosion plume formed upon ablation of the material the target. Under deposition conditions, we changed the width of the filtering window, the repetition rate of the atomized material passing through the filter onto the substrate, and the radiation energy density of the KrF excimer laser on the target surface. At deposition rates of less than 0.1 nm s–1, the values of T(R = 0) did not exceed 77 K, and pyramids were formed on the surface of the films up to 80 nm in height along the c axis in the form of spirals with rectangular bases and steps of 1–2 nm along the lateral faces. With an increase in the deposition rate from 0.1 to 0.6 nm s–1, T(R = 0) increased to 86 K. These regimes corresponded to a wavy pyramid surface up to 40 nm in height with rounded bases up to 1500 nm in diameter and irregular steps 1–4 nm on the side slopes. Faceted crystals with a width from 20–30 to 500 nm in the base grew along the boundaries between the pyramids during the deposition. This morphology of the growth surface was explained by the high flow rate of the sputtered material, which is determined by the frequency filtering of the erosion plume and the energy density in the pulse upon predominantly surface diffusion.

2019, Zinin, P. V., Filonenko, V. P., Fominski, V. Y., Romanov, R. I., Solov'ev, A. A., Vasil'evskii, I. S., Safonov, D. A., Ivanov, A. A., Фоминский, Вячеслав Юрьевич, Романов, Роман Иванович, Соловьев, Алексей, Васильевский, Иван Сергеевич, Сафонов, Данил Андреевич, Иванов, Андрей Анатольевич

© 2019, Pleiades Publishing, Ltd.Abstract: The morphology, chemical composition, microstructure, and electrical properties of BC3 thin films subjected to melting by a nanosecond laser pulse are investigated. The original films have been created by pulsed laser codeposition of B and C onto a sapphire substrate at 150 and 350°C. Morphological changes in the films depended on their initial structural state. However, a “frozen” structure of both films after irradiation corresponded to the B-saturated graphite-like phase, the local composition of which varied due to the formation of inclusions of amorphous boron carbide. Before and after irradiation, the films exhibited a slightly decreasing dependence of the surface resistance with increasing temperature from 4.2 to 330 K. After laser irradiation, the films resistance has decreased by a factor of ~2.6.