Registration Number
0217U007375,
0117U007266
, R & D reports
Title
Influence of spatial inhomogeneity and time dependent perturbations on the properties of the superconducting junctions
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Head
Zolotaryuk Yaroslav Oleksandrovych, Доктор фізико-математичних наук
Registration Date
02-01-2018
Organization
Bogolyubov Institute for Theoretical Physics of National Academy of Sciences of Ukraine
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The object of research is low-dimensional hybrid systems (junctions), where superconductors are present. In particular, superconductor-normal metal-insulator-normal metal-superconductor (SNINS) junctions, ferromagnetic-superconductor-ferromagnetic (FSF) and double-gap superconductors were investigated. The purpose of work is to determine the influence of decoupling and external magnetic field effects on the stationary properties of SNINS junctions in the presence of nonmagnetic impurities of arbitrary concentration, to construct an exactly solvable model of FSF junction that takes into account the proximity and Fulde-Ferrell-Larkin-Ovchinnikov effects, to extend the functional integral method for finding the statistical sum of two-gap superconductors. The methods of investigation are Ginzburg-Landau equation, Bogolyubov- de Genes equation, the functional integral method. For the SNINS junction the dependencies of current on the phase difference for arbitrary values of the normal metal layer thickness, on the electron transmission coefficient and on the degree of contamination with nonmagnetic impurities are obtained. In an external magnetic field near the critical temperature is shown that the presence of a dielectric layer and a normal region in the junction significantly affect the magnitude of the critical current and the form of it dependence on magnetic field. Sensitivity of the maximum current to the change of the magnetic flux especially noticeable during the increasing of the electron transmission coefficient. However, the change of the mean free path does not significantly affect this dependence. The Bogolyubov-de Genes equations are exactly solved for a predefined pairing potential, the quasiparticles wave functions, transmission coefficients and total unpolarized current through the junction which depends on the temperature and the pairing potential are calculated. The region of total reflection from the superconducting layer is found for a certain interval of incident electrons energies. Applying the method of functional integration, it is shown that the problem of statistical sum calculation for two-gap superconductor is divided into the problem of calculation the statistical sum of free electrons system that are in the field of electron pairs complex sources and the problem of averaging the obtained result in the space of electron pairs complex sources with a Gaussian distribution.5481
Product Description
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Золотарюк Ярослав Олександрович
Пастух Олександр Юрійович
Сахнюк Василь Євгенович
Свідзинський Анатолій Вадимович
Стародуб Іван Олексійович
Шутовський Арсен Миколайович
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2020-04-02
