Among classical applications of superconductivity, various microelectronic devices are of key importance. As a rule, such devices represent a thin superconductor film on a substrate, structured in the shape controlled by the device design. Structuring can be performed by various methods; simplest and most commonly used one is the liquid acid etching over the photoresist mask. In this work, we study the etching process of thin films of high-temperature superconductor YBa2Cu3O7 – δ using an etchant based on a 0.2% of nitric acid aqueous solution modified by an ammonium fluoride addition. The latter inhibits the etching process to a value convenient for manual treatment. As the addition concentration increases, the etching rate decreases to the total process shutdown. At an NH4F concentration of 0.3‰, an etching rate of 6 ± 2 nm/s was reached, which can be considered as optimum for manual treatment of films to 100 nm thick.

The giant magnetostriction of the Bi2Sr2 – xLaxCuO6 + δ (La-Bi2201) single crystal at x = 0.8 is first detected for the low-temperature region. This composition is at the insulator/superconductor interface of the phase diagram of the La-Bi2201 high-temperature superconductor (HTS). The sample is heavily underdoped, nonsuperconducting La-Bi2201, and previously exhibited anomalous magnetically dependent negative thermal expansion at low temperatures. We observe the giant magnetostriction of ~10–4 known for superconducting HTS cuprates. The effect is observed in the temperature range from 6 to 70 K. The results point to the residual fluctuating superconductivity which is observed in HTS to high temperatures.

The giant magnetostriction of the Bi 2 Sr 2 – x La x CuO 6 + δ (La-Bi2201) single crystal at x = 0.8 is first detected for the low-temperature region. This composition is at the insulator/superconductor interface of the phase diagram of the La-Bi2201 high-temperature superconductor (HTS). The sample is heavily underdoped, nonsuperconducting La-Bi2201, and previously exhibited anomalous magnetically dependent negative thermal expansion at low temperatures. We observe the giant magnetostriction of ~10 –4 known for superconducting HTS cuprates. The effect is observed in the temperature range from 6 to 70 K. The results point to the residual fluctuating superconductivity which is observed in HTS to high temperatures.

Tensometric study of n-type Bi2Se3 single crystals in dc magnetic fields to 6 T in a temperature range of 7–23 K detected a weak negative thermal expansion (NTE) in the basal plane. The NTE increases with the field strength and depends on its orientation with respect to the trigonal c axis. In a magnetic field of 6 T, parallel to the c axis, the linear NTE coefficient reaches −7 · 10−7 K−1, and a minimum sample length is reached at a temperature of 13 K, where a Hall carrier concentration maximum is also detected. The found magnetoelastic anomaly can be associated with the topological insulator state.

A comparative assessment of pedogenetic processes in solonetzes (Calcic Gypsic Salic Solonetzes (Siltic, Albic, Cutanic, Differentic)) developing on terraces of lake depressions within the Volga–Ural interfluve of the Caspian Lowland has been performed on the basis of data on their macro- and micromorphological features and chemical, physicochemical, and physical properties. The studied soils have number of common characteristics shaped by the humus-accumulative, solonetzic, eluvial–illuvial, calcification, and gypsification processes. However, it is shown that macro- and micromorphological indicators of solonetzic processes (the development of clay–humus coatings and the character of structural units in the solonetzic (B) horizon) do not always agree with the modern physicochemical conditions of the development of this process. This is explained by differences in the degree and chemistry of the soil salinization and the depth and salinity of the groundwater. Solonetzes developing on the second terrace of Playa Khaki are distinguished by the highest water content and maximum thickness of the horizons depleted of soluble salts. They are characterized by the well-pronounced humus-accumulative process leading to the development of the light-humus (AJ) horizon. In other solonetzes, the accumulation of humus is weaker, and their topsoil part can be diagnosed as the solonetzic-eluvial (SEL) horizon. Active solodic process and illuviation of organomineral substances with the development of thick coatings and infillings in the B horizon are also typical of solonetzes on the second terrace of Playa Khaki. Micromorphological data indicate that, at present, layered clayey coatings in these soils are subjected to destruction and in situ humification owing to the active penetration of plant roots into the coatings with their further biogenic processing by the soil microfauna. The process of gleyzation (as judged from the number of Fe–Mn concentrations) is most active in solonetzes developing on the first terrace of Playa Khaki. These soils are also characterized by the highest degree of salinization with participation of toxic salts. The maximum accumulation of gypsum is typical of the heavy-textured horizons.

The current state and resilience to wildfire disturbances of the natural tamarisk ( Tamarix laxa Willd) communities at on the coasts of Lake Buluchta, a salt lake, Caspian Depression (the Volga and Ural Rivers interfluve) is considered. The unique ecosystems of the natural Tamarisk communities are able to persist in specific biotopes of natural water basins only.

Morphological and chemical properties of soils in a soil catena crossing the eastern coast of salt Bulukhta Lake in the northern part of the Caspian region were studied. The catena included different kinds of solonetzes and solonchaks occupying the lake bottom. The morphogenetic and analytical study of the soils made it possible to judge the intensity of the major soil-forming processes on different elements of the local topography. It was shown that the intensity of humus accumulation increases from the autonomous eluvial positions towards the accumulative positions and decreases in the superaqual landscape, where the accumulation of organic matter is limited by the high soil salinity and by the washout of humified material from the shore into the lake. In the transitional and accumulative positions of the catena with saline parent materials, the upper soil horizons are subjected to desalinization owing to the additional water inflow and transformation of surface runoff into subsurface water flows along zoogenic pores. A comparative analysis of the seasonal dynamics of the level, salinity, and chemical composition of groundwater under the soils of the catena was performed. It demonstrated that the dynamics of the groundwater level and salinity in the geochemically subordinate positions depend on the hydrological regime of the lake, which, in turn, is controlled by the amount and seasonal distribution of precipitation.

Изучены морфологические и химические свойства почв сопряженных по рельефу ландшафтов восточного берега соленого оз. Булухта. Почвенная катена представлена солонцами, различающимися на уровне вида, и солончаками, занимающими днище озера. На основании морфогенетического и аналитического изучения свойств почв дана оценка степени выраженности основных почвообразовательных процессов в разных позициях рельефа. Показано, что процессы гумусонакопления нарастают от элювиальных позиций к аккумулятивным, снижаясь в супераквальном ландшафте, где накопление органического вещества ограничено сильным засолением почв и темпами смыва гумусированного материала с берега. В транзитной и аккумулятивной позициях катены на фоне грунтового засоления, происходит рассоление верхних почвенных горизонтов за счет дополнительного притока влаги и перевода поверхностного стока во внутрипочвенный по зоогенным пустотам. Проведен сравнительный анализ сезонной динамики уровня, минерализации и состава грунтовых вод под почвами катены. Выявлено, что в подчиненных ландшафтах динамика уровня и минерализации грунтовых вод зависит от гидрологического режима озера, который в свою очередь определяется количеством и распределением осадков в течение сезона.

The effect of digging activity of little souslik ( Spermophilus pygmaeus Pall.) on the microtopography and soils was studied in the areas with shallow saline groundwater developing under continental conditions for 10.5–12.7 ka. The portion of microtopographic features related to the digging activity was quantified. It was found that the micromounds formed by sousliks appear on recently dried surfaces with shallow saline groundwater. However, their portion in this case is less than 3% because of the poor vegetation and shallow groundwater. Then, with the lowering of the base of erosion and aging of the territory, the zoogenic effect becomes more pronounced. On the first terrace of Khaki Sor (salt lake), the digging activity of sousliks creates the initial heterogeneity of soils and vegetation. The soil cover is composed of the virgin quasigleyed solonchakous solonetzes under the Atriplex-Artemisia santonica association (Gypsic Salic Solonetz (Albic, Ruptic, Oxiaquic, Siltic)) and of the zooturbated solonetzes under the Artemisia santonica-A. lerchiana association (Endosalic Hypogypsic Gypsisol (Sodic, Siltic, Novic)). A comparative analysis of morphology and some chemical properties of virgin and zooturbated soils is given. The soils of souslik-made mounds are strongly mixed, and the structure of their horizons is completely disturbed. They are characterized by an increased total content of salts mainly due to gypsum accumulation. At the same time, the content of toxic salts in the soil profile remains rather high because of their ascending migration from the strongly saline groundwater. On the first terrace, the process of zoogenic amelioration of solonetzes by sousliks is limited and does not affect deep soil layers.

An experimental-computational algorithm of precisely determining the dependence of the local critical current density in a superconducting film on the local magnetic field is developed. The determination is performed proceeding from the dependence of the transport critical current through a wide superconducting tape on the external magnetic field. It is shown that the existing formulas approximating this dependence do not allow the solution of this problem with an accuracy provided by modern experimental techniques. To provide a necessary accuracy of the solution, a four-parametric approximation formula is proposed and the parameters of this dependence are determined by the example of the second-generation HTSC tape.

The thermal expansion of a high-quality 2H-NbSe 2 single crystal is precisely measured in the basal plane and the temperature range 5.7–50 K. An anomaly of the thermal expansion in the basal plane is detected, and it is found to be caused by a superconducting transition. The change in thermal expansion coefficient α ab is used to calculate the pressure derivative of the critical temperature ( dT c / dp ab ) = (19.0 ± 2.0) × 10 −9 K/Pa, and this derivative agrees well with the reported data. An additional anomaly, which indicates a phase transition, is also detected in the pretransition range. The nature of the detected phase transition is discussed.

The temperature dependence of the linear thermal expansion coefficient (TEC) of an InSe single crystal in the (001) plane is measured in the temperature range 7–50 K. A peak in the thermal expansion is detected near T = 10 K, after which the sample shrinks upon heating. The effect of an external magnetic field of up to 6 T, which is parallel to the (001) plane, on the TEC is investigated. The observed partial suppression of the peak and crystal compression by the field indicates the relation of these anomalies to possible electron ordering in InSe layers.

Измерена температурная зависимость линейного коэффициента теплового расширения (КТР) монокристалла InSe в плоскости (001) в области температур 7-50 К. Обнаружен максимум теплового расширения около Т = 10 К, после которого с ростом температуры образец сжимается. Исследовано влияние на КТР внешнего магнитного поля до 6 Тл, параллельного плоскости (001). Выявлено частичное подавление максимума и сжатия кристалла магнитным полем, указывающее на связь этих аномалий с возможным электронным упорядочением в слоях InSe.

The spatial organization of nature systems on shores of lake Bulukhta with variable water level (North Precaspian lowland) was examined by field investigations. The regularities of the composition and spatial structure of the soil-vegetation cover and the peculiarities of the seasonal dynamics and mineralization of the water table were determined. The possibility of applying the ecotone concept as a methodological approach when studying the spatial and functional organization of the soil-vegetation cover and the dynamics of shores of lakes with variable water levels under arid climate conditions has been presented.