Наукові видання. Фізичний факультет
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Документ Absorption spectra of layered ZnI2 and K2ZnI4 compounds intercalated by СО2(Institute for Single Crystals, 2009) Yunakova, O.N.; Miloslavsky, V.K.; Kovalenko, E.N.; Makovetsky, E.D.The absorption spectra of thin films of ZnI2 and K2ZnI4 layered compounds intercalated with СО2 molecules have been investigated in temperature interval from 90 to 240 K. It is found that the intercalation results in high-frequency shift of exciton bands and their broadening. Considering the structure of ZnI2 and K2ZnI4 crystal lattices, the most probable positions of СО2 molecules in spacings between layers of compounds have been established. It is shown that, in K2ZnI4 compound, unlike ZnI2, there are two position types of intercalant molecules with molecular axes of different orientation relative to the compound crystallographic axes.Документ Comparison of refractive indices of amorphous and crystalline As2S3(Institute for Single Crystals, 2009) Miloslavsky, V.K.; Makovetsky, E.D.Method to calculate refractive index and transparency range dispersion of amorphous As2S3 is proposed. It is based on effective dielectric permittivity models for porous composite media, comparison of glass and crystal density and use of data on refractive index of the crystal. It is shown that the best agreement of calculated and experimental values of refractive index of glass is obtained within the wavelength interval 460-670 nm when using Lorenz-Lorentz formula. It is established that As2S3 glasses possess pores with filling factor q=0.057 submerged to isotropic matrix with approximately two times smaller porosity (qM=0.031).Документ Crossover from dirty to clean superconducting limit in dc magnetron-sputtered thin Nb films(Elsevier, 2012-05-11) Dobrovolskiy, O.V.; Huth, M.High-quality Nb (110) thin films with residual resistance ratios up to 60 and critical temperatures Tc≈9.27 K have been prepared by conventional dc-magnetron sputtering on α-Al2O3 by careful selection of the sputtering conditions. This allowed for a systematic study of the influence of the growth rate on the structural quality and the superconducting properties of the films. The optimized growth conditions were revealed at the substrate temperature Ts=850 °C, Ar pressure Ps=0.4 Pa, and the growth rate g≃0.5 nm/s. The results of the films' structural characterization by X-ray diffraction, reflection high-energy electron diffraction, and atomic force microscopy are presented. In terms of the electron mean free path l and the superconducting coherence length ξ, deduced from the magneto-resistivity data, the clean superconducting limit (l>ξ) is realized in the high-purity films. For comparison, in impure Nb films sputtered at room temperature while keeping the rest of the sputtering parameters unvaried, the opposite dirty limit (ξ≳l) ensues. The merits of these findings are discussed in the context of the demands of present-day fluxonics devices regarding the normal-state and flux-flow properties of superconducting films they are made of.Документ Determination of coordinate dependence of a pinning potential from a microwave experiment with vortices(LOW TEMPERATURE PHYSICS, 2013-02) Dobrovolskiy, O.V.; V. A. Shklovskij, V.A.The measurement of the complex impedance response accompanied by power absorption P(x) in the radiofrequency and microwave ranges represents a most popular experimental method for the investigation of pinning mechanisms and vortex dynamics in type-II superconductors. In the theory, the pinning potential (PP) well for a vortex must be a priori specified in order to subsequently analyze the measured data. We have theoretically solved the inverse problem at T¼0K and exemplify how the coordinate dependence of a PP can be determined from a set of experimental curves P(xjj0) measured at subcritical dc currents 0Документ Dispersion of refractive index in thin films CdI2 and ZnI2(Institute for Single Crystals, 2010) Yunakova, O.N.; Miloslavsky, V.K.; Kovalenko, E.N.The refractive index dispersion in thin CdI2 and ZnI2 films has been measured in the wavelength interval 300-1000 nm and processed using the monooscillator model ageeing well with experimental data. The optical permittivity e_unlim of both compounds has been determined using the found parameters of this model, the optical permittivity data have been used in the further analysis of exciton states in CdI2 and ZnI2, in particular, for determination of 1s exciton radius. The found a_ex values are close to the unit cell parameters of the compounds, thus indicating that the excitons in two compounds belong to excitons of the intermediate electron-hole band.Документ Electron spin waves in nonmagnetic conductors with resonance states of electrons(Karazin Kharkiv National University, 2008) Ermolaev, A.M.; Ulyanov, N.V.Results of theoretical investigation of properties of spin waves in nonmagnetic conductors and heterostructures with 2D electron gas in presence of impurity atoms be able to localize electrons are listed in monograph.Документ Interactions between Sheets of Phonons in Liquid 4He(2003-12-05) Vovk, R.V.; Williams, C.D.H.; Wyatt, A.F.G.We have created two sheets of 1 K phonons in liquid 4He at 55 mK such that they intersect each other as they move towards a common point. If the two sheets have a small angle between them, they interact strongly and create a hot line in the liquid helium. This line is continuously fed with energy from the two sheets and loses energy by creating high-energy phonons. If the angle between the sheets is larger than 30 they do not interact but pass through each other. These results give direct evidence for the composition of the sheets: they comprise strongly interacting low-energy phonons which occupy a narrow cone in momentum space.Документ Landau-Silin spin waves in conductors with impurity states(LAP LAMBERT Academic Publishing GmbH & Co. KG, Germany, 2012) Ermolaev, A.M.; Ulyanov, N.V.; Ермолаев, А.М.; Ульянов, Н.В.Theoretical investigation results of spin waves properties in nonmagnetic conductors and heterostructures with 2D electron gas in presence of impurity atoms be able to localize electrons are listed in monograph. The effect of quasi-local and magnetoimpurity states of electrons on dynamic spin susceptibility of electron gas, on spectrum and damping of spin waves are considered. New branches due to electron impurity states in spin wave spectrum are predicted. Methods of diagnostics of these waves in experiments with slow neutrons are proposed. Impurity atoms in a conductor exert a complicated influence on quasi-particle energy spectrum. They cause shift and spread of energy zones as well as state density rearrangement accompanied by appearance of both local and quasi-local levels. A local state concept in non-ideal crystalline lattice oscillation spectrum has been suggested by I.M.Lifshits [1] in 1940s. These investigations were continued in the Kagan and Iosilevskii [2, 3] and Brout and Visscher [4] articles in which impurity atom quasi-local oscillations in lattice was predicted. A theory of other quasi-particles electrons and magnons was been elaborated at the same time.Документ Material composition – Pinning strength correlation in Nb thin films with focused ion beam-milled washboard nanostructures(Physica C, 2013-03-29) Dobrovolskiy, O.V.; Begun, Evgenia; Huth, M.; Shklovskij, V.A.An analysis of the interrelated changes in the material composition and the pinning strength in nanostructured Nb (110) thin films is presented. The nanopatterns were prepared by focused ion beam milling of an array of uniaxial grooves. They induce a washboard-like pinning potential landscape for vortices in the mixed state. By applying different magnetic fields, the most likely pinning sites along which the flux lines move through the samples have been selected. By this, either the background isotropic pinning of the pristine film or the enhanced isotropic pinning originating from the nanoprocessing has been probed. The enhanced pinning strength in the processed films has been found to correlate with the content of Ga implanted into the films during the nanopatterning.Документ Noise-Assisted Microwave Up-conversion by Vortices in Thin-Film Superconductors with a dc-Biased Washboard Pinning Potential(Springer Science+Business Media New York 2012, 2012-12-20) Shklovskij, V.A.; Dobrovolskiy, O.V.; Huth, M.So far the main theoretical basis for understanding and optimization of the microwave properties of vortices in type II superconductors has been relying upon the Coffey–Clem (CC) approach for the linear impedance at nonzero temperature. However, the CC model does not account for the non-linear response and the possibility to control it by changing the value of the dc transport current in a superconducting sample. For this reason, we have exactly solved the Langevin equation for the two-dimensional nonlinear vortex dynamics in a dc bias-tilted cosine pinning potential in the presence of an ac current of arbitrary amplitude and frequency ω and have, thereby, substantially generalized the CC results. In this work we analyze the behavior of the non-linear response on kω-frequency in a wide range of dc and ac current densities, ω, and temperature. The kω- response is found to depend strongly on all these parameters, as exemplified for the third-harmonic (k = 3) transformation coefficient Z3. The parametric window for the most enhanced up-conversion is presented. The predicted effects can be experimentally verified in thin-film superconductors with some pinning potential of the washboard type.Документ On the nature of photoinduced absorption in photochromic (AgCl)x(CuCl)1-x films(Institute for Single Crystals, 2005) Yunakova, O.N.; Miloslavsky, V.K.; Gromov, M.S.; Kovalenko, E.N.Absorption spectrum of photochromic (AgCl)x(CuCl)1-x films has been studied. The intense band of induced absorption in visible region has been established to be a superposition of two bands, namely, that of absorption by silver colloid particles shaped as ellipsoids or chains of spherical particles and absorption band of Cu2+ ions in AgCl.Документ Optical properties of nanostructures(Institute for Single Crystals, 2008) Miloslavsky, V.K.; Ageev, L.A.; Makovetsky, E.D.; Maskevich, S.A.The paper is a brief review of optical properties of nanostructures containing metal nanoparticles. There is a deduction of some simple formulae describing optical spectra of composites containing small particles of various form. Comparison of theoretical and experimental data has been carried out. Conclusions following Mie theory of diffraction on spheres of various diameters and dielectric permittivities are discussed. Various examples of applications of nanoparticles and their influence on surrounding media are given.Документ Surface Energy and Wetting in Island Films(InTech, Rijeka, 2015) Dukarov, S.V.; Kryshal, A.P.; Sukhov, V.N.The chapter describes the fundamental aspects of the effects of scale on surface phenomena in condensed films. Experimental and theoretical data for the size and temperature dependencies of the surface energy (including the solid phase); wetting of solid surfaces and free thin films by small metal particles are discussed. Several modern methods of contact angle measurement in small-sized systems based on the optical and electron microscopy methods are described.Документ Владимир Владимирович Ульянов(Харьков: ХНУ, 2004) Василевская, Ю.В.; Ермолаев, А.М.Посвящается Владимиру Владимировичу Ульянову – замечательному физику-теоретику, профессору кафедры теоретической физики, много лет заведовавшему этой кафедрой, воспитавшему многих известных физиков.Документ Интегральные методы в квантовой механике(Харьков. Издательство при Харьковском государственном университете издательского объединения „Вища школа”, 1982) Ульянов, В.В.Монография посвящена развитию и применению некоторых современных интегральных (нелокальных) методов в нерелятивистской квантовой механике. Значительная часть материала еще не освещалась в книгах по квантовой теории.Документ Капиллярные свойства островковых пленок и малых частиц(ХНУ имени В. Н. Каразина, 2015) Гладких, Н.Т.; Дукаров, С.В.; Крышталь, А.П.; Ларин, В.И.; Сухов, В.Н.В монографии обобщаются исследования поверхностных явлений в конденсированных пленках. Приводятся обширные экспериментальные и теоретические результаты по размерной и температурной зависимости поверхностной энергии, в том числе и в твердой фазе; смачиванию малыми частицами поверхности твердых тел, свободных тонких пленок и пленок на подложках при различном характере физико-химического взаимодействия компонентов. Изложены современные методы исследования смачивания в нанодисперсных системах, основанные на применении оптической и электронной микроскопии. Для специалистов в области физики твердого тела, физики пленок и поверхностных явлений, а также студентов старших курсов физических и физико-технических специальностей.Документ Компьютерные исследования квантовых явлений. Ч. 1(Х.: ХНУ имени В.Н. Каразина, 2012) Ульянов, В.В.; Ульянов, Н.В.Книга продолжает серию монографий и учебных пособий, приуроченную к 200-летию Харьковского университета и физического факультета, а также 70-летию кафедры теоретической физики имени академика И.М.Лифшица. Рассматриваются различные квантовые явления с помощью компьютерных методов исследования: аналитических, численных и графических. Первая часть посвящена связанным стационарным состояниям. Изучаются особенности степенных потенциалов как ангармонических осцилляторов, исследуется туннельное расщепление энергии в несимметричных случаях и критических ситуациях. Применяются квазиклассические и вариационные методы, а также численные расчеты и графические представления, включая анимационные демонстрации. Обсуждаются эффективные потенциалы спиновой природы и потенциальные поля солитонного происхождения. Монография может служить также интерактивным учебным пособием. Она рассчитана на широкий круг лиц: преподавателей, научных работников, студентов физических специальностей вузов и других читателей, интересующихся современными методами квантовой теории. К книге прилагается компакт-диск с оригинальными компьютерными разработками авторов, анимационными демонстрациями, цветными иллюстрациями и электронными изданиями книг авторов.Документ Мои университетские учителя. Часть четвертая.(Харьковский национальный университет имени В.Н. Каразина, 2008) Ермолаев, А.М.Вниманию читателей предлагаются воспоминания автора о преподавателях физического факультета Харьковского университета. Издание приурочено к 200-летию нашего Университета. Посвящается светлой памяти преподавателей, безвременно ушедших. Это четвертая часть воспоминаний. В ней собраны рассказы, опубликованные ранее в отдельных изданиях, посвященных физикам- теоретикам. Для широкого круга читателей.Документ Новые квазиточнорешаемые модели в квантовой теории спиновых систем(Харьковский национальный университет, 2005) Василевская, Ю.В.; Ульянов, В.В.В монографии получены новые точные решения уравнения Шредингера, имеющие простые явные аналитические выражения для потенциальных полей, уровней энергии и волновых функций стационарных состояний.Документ О квазиклассическом движении частиц в полях с особенностями(Харьков: ХНУ, 2002) Ульянов, Владимир Владимирович; Ульянов, Володимир ВолодимировичСборник содержит несколько статей, написанных автором в начале 70-х годов прошлого столетия.