Magnetic anisotropy in strained manganite films and bicrystal junctions

Transport and magnetic properties of LSMO manganite thin films and bicrystal junctions were investigated. Manganite films were epitaxially grown on STO, LAO, NGO and LSAT substrates and their magnetic anisotropy were determined by two techniques of magnetic resonance spectroscopy. Compare with cubic substrates a small (about 0.3 persentage), the anisotropy of the orthorhombic NGO substrate leads to a uniaxial anisotropy of the magnetic properties of the films in the plane of the substrate. Samples with different tilt of crystallographic basal planes of manganite as well as bicrystal junctions with rotation of the crystallographic axes (RB - junction) and with tilting of basal planes (TB - junction) were investigated. It was found that on vicinal NGO substrates the value of magnetic anisotropy could be varied by changing the substrate inclination angle from 0 to 25 degrees. Measurement of magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetically ordered spin subsystems for both types of bicrystal boundaries RB and TB. The magnitude of the magnetoresistance for TB - junctions increased with decreasing temperature and with the misorientation angle even misorientation of easy axes in the parts of junction does not change. Analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the LSMO bicrystal junctions can be caused by two scattering mechanisms with the spin- flip of spin - polarized carriers due to the strong electron - electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the spin-flip by anti ferromagnetic magnons at high temperatures.Comment: 26 pages, 10 figure

Evidence for spin-triplet superconducting correlations in metal-oxide heterostructures with non-collinear magnetization

Heterostructures composed of ferromagnetic La0.7Sr0.3MnO3, ferromagnetic SrRuO3, and superconducting YBa2Cu3Ox were studied experimentally. Structures of composition Au/La0.7Sr0.3MnO3/SrRuO3/YBa2Cu3Ox were prepared by pulsed laser deposition, and their high quality was confirmed by X-ray diffraction and reflectometry. A non-collinear magnetic state of the heterostructures was revealed by means of SQUID magnetometry and polarized neutron reflectometry. We have further observed superconducting currents in mesa-structures fabricated by deposition of a second superconducting Nb layer on top of the heterostructure, followed by patterning with photolithography and ion-beam etching. Josephson effects observed in these mesa-structures can be explained by the penetration of a triplet component of the superconducting order parameter into the magnetic layers.Comment: 10 pages, 6 figure

Novel Regime of Operation for Superconducting Quantum Interference Filters

A new operating regime of the Superconducting Quantum Interference Filter (SQIF) is investigated. The voltage to magnetic field response function, V(H), is determined by a Fraunhofer dependence of the critical current and magnetic flux focusing effect in Josephson junctions (F-mode). For SQIF-arrays made of high-Tc superconducting bicrystal Josephson junctions the F-mode plays a predominant role in the voltage-field response V(H). The relatively large superconducting loops of the SQIF are used for inductive coupling to the external input circuit. It is shown that the output noise of a SQIF-array measured with a cooled amplifier in the 1-2 GHz range is determined by the slope of the V(H) characteristic. Power gain and saturation power were evaluated using low frequency SQIF parameters. Finally, we consider the influence of the spread in the parameters of Josephson junctions in the SQIF-array on the V(H) characteristic of the whole structure.Comment: 7 pages, 4 figure

Coupling of the lattice and superlattice deformations and hysteresis in thermal expansion for the quasi one-dimensional conductor TaS3_3

An original interferometer-based setup for measurements of length of needle-like samples is developed, and thermal expansion of o-TaS$_3$ crystals is studied. Below the Peierls transition the temperature hysteresis of length $L$ is observed, the width of the hysteresis loop $\delta L/L$ being up to $5 \cdot 10^{-5}$. The behavior of the loop is anomalous: the length changes so that it is in front of its equilibrium value. The hysteresis loop couples with that of conductivity. The sign and the value of the length hysteresis are consistent with the strain dependence of the charge-density waves (CDW) wave vector. With lowering temperature down to 100 K the CDW elastic modulus grows achieving a value comparable with the lattice Young modulus. Our results could be helpful in consideration of different systems with intrinsic superstructures.Comment: 4 pages, 3 figures. Phys. Rev. Lett., accepted for publicatio

Voltage-current and voltage-flux characteristics of asymmetric high TC DC SQUIDs

We report measurements of transfer functions and flux shifts of 20 on-chip high T$_C$ DC SQUIDs half of which were made purposely geometrically asymmetric. All of these SQUIDs were fabricated using standard high T$_C$ thin film technology and they were single layer ones, having 140 nm thickness of YBa$_2$Cu$_3$O$_{7-x}$ film deposited by laser ablation onto MgO bicrystal substrates with 24$^0$ misorientation angle. For every SQUID the parameters of its intrinsic asymmetry, i. e., the density of critical current and resistivity of every junction, were measured directly and independently. We showed that the main reason for the on-chip spreading of SQUIDs' voltage-current and voltage-flux characteristics was the intrinsic asymmetry. We found that for SQUIDs with a relative large inductance ($L>120$ pH) both the voltage modulation and the transfer function were not very sensitive to the junctions asymmetry, whereas SQUIDs with smaller inductance ($L\simeq 65-75$ pH) were more sensitive. The results obtained in the paper are important for the implementation in the sensitive instruments based on high T$_C$ SQUID arrays and gratings.Comment: 11 pages, 4 tables, 17 figures This version is substantially modified. The Introduction and Section 2 are completely rewritten, while experimental part is mainly the same as in previous versio

Технологічні особливості зварювання інфрачервоним випромінюванням елементів інфузійних медичних систем на основі стирольних кополімерів СEБС

Технологічні особливості зварювання інфрачервоним випромінюванням елементів інфузійних медичних систем на основі стирольних кополімерів СEБС = Technological features of welding infrared emissions of infusion medical systems on the styrene copolymers SEBS / В. В. Таланюк, А. О. Шадрін, М. Г. Кораб, М. В. Юрженко // Зб. наук. пр. НУК. – Миколаїв : НУК, 2020. – № 2 (480). – С. 34–41.Анотація. Термопластичні еластомери (ТПЕ) – це матеріали, що мають пружні властивості, які подібні до гуми, однак здатні до плавлення, та яким притаманні всі характерні властивості термопластів. За хімічним складом розрізняють декілька видів термопластичних еластомерів: поліамідні, поліетерові, поліуретанові та стиренові кополімери. Разом із кополімерами широко застосовуються також блок-кополімери, для яких характерна наявність у структурі їхніх макромолекул ланок різних полімерів. До таких полімерів, наприклад, належить стирол-етилен-бутилен-стирол блок-кополімер (СЕБС) – новий біосумісний полімерний матеріал, який знаходить широке застосування в різноманітних галузях промисловості, наприклад, у будівництві, автомобіле- та приладобудування тощо. Стирол-етилен-бутилен-стирол блок-кополімер належить до стирольних блок-кополімерів другого покоління, вироби з яких мають високі фізико-механічні властивості, а його біосумісність також дозволяє використовувати його в медичній галузі. У роботі наведені основні характеристики та проведено аналіз переваг термопластичних еластомерів на прикладі стирол-етилен-бутилен-стирол блок-кополімеру в порівнянні із традиційними для окремих галузей промисловості полімерними матеріалами. Стирол-етилен-бутилен-стирол блок-кополімер – це конструкційний термопластичний полімерний матеріал, який за властивостями подібний до синтетичних каучуків, еластичний або жорсткий залежно від хімічної будови, досить термостійкий, стійкий до впливу різноманітного середовища, зокрема й озону, ультрафіолетового випромінювання й інших атмосферних явищ. Він не має вираженого смаку та запаху, може контактувати з різноманітними харчовими продуктами та біологічними тканинами. Уважається, що стирол-етилен-бутилен-стирол блок-кополімер відносно важко піддається переробці під час розплавлення, тому його іноді змішують із блок-кополімерами, які підвищують його здатність до переробки та формування виробів. Унікальне поєднання теплофізичних, хімічних, діелектричних властивостей, здатність до повторної переробки зумовили широке використання стирол-етилен-бутилен-стирол блок-кополімеру як конструкційного матеріалу та компонента різних компаундів у багатьох галузях промисловості: в автомобілебудуванні – еластичні деталі салону, килимки, пильники, покриття для педалей, ущільнювачі; у побутовій і оргтехніці – гнучкі та теплостійкі деталі, сидіння для велосипедів, еластичні деталі мобільних телефонів, корпуси пультів дистанційного керування, елементи комп’ютерних клавіатур та мишок, гнучкі деталі авторучок, корпуси дитячих іграшок, зубних щіток, елементи аксесуарів для купання – підводних костюмів, ласт, масок; у виробництві інструментів – рукоятки для ручних і електроінструментів, рукоятки ножів, елементи будівельних інструментів – пензлів, кельм тощо; у виробництві взуття – підошви й інші еластичні деталі побутового, спортивного та спеціального взуття; у електротехніці – гнучкі роз’єми, ізоляція дротів тощо; у сантехніці – ущільнення, гофровані гнучкі шланги тощо; у медичній промисловості – гнучкі та жорсткі ємності, медичні трубки, інфузійні та трансфузійні системи, елементи лабораторного обладнання. Насамперед у медичній галузі стирол-етилен-бутилен-стирол блок-кополімер активно застосовується як заміна традиційних полімерних матеріалів, які багато років використовуються та мають багато недоліків.Abstract. Thermoplastic elastomers (TPE) are materials that have elastic properties, which are similar to rubber, but able to melt and have all the characteristic properties of thermoplastics. Several types of thermoplastic elastomers are determined by chemical composition: polyamide, polyether, polyurethane and styrene copolymers. Together with copolymers, block copolymers are also widely used, for which the presence of various polymers in their macromolecules is characteristic. Such polymers, for example, include styrene-ethylene-butylene-styrene block copolymer (SEBS), a new biocompatible polymeric material that is widely used in a variety of industries, for example, construction, automotive and instrumentation, etc. SEBS refers to styrene block copolymers of the second generation, the products of which have high physical and mechanical properties, and its biocompatibility also allows it to be used in the medical field. The main characteristics and analysis of advantages of the TPE based on SEBS compared with traditional polymeric materials for certain industries are presented in this work. SEBS is a structural thermoplastic polymeric material, which has properties similar to synthetic rubbers, elastic or rigid, depending on its chemical structure, is sufficiently heat-resistant, resistant to various environments, including ozone, ultraviolet radiation and other atmospheres. It has no pronounced taste and odor, can contact with a variety of food and biological tissues. SEBS is relatively difficult to process when melted, so it is sometimes mixed with block copolymers that enhance its processing ability and formation of products. The unique combination of thermophysical, chemical, dielectric properties, recyclability has led to the widespread use of SEBS as a structural material and component of various compounds in many industries: – automotive – elastic cabin parts, mats, mud guards, saws, pedal coatings, seals; – household and office equipment – flexible and heat-resistant parts, bicycle seats, elastic parts of mobile phones, cases of remote controls, elements of computer keyboards and mice, flexible parts of pens, cases of toys, toothbrushes, elements of bathing accessories – underwater suits , fins, mask; – tool making – hand and power tool handles, knife handles, construction tools – brushes, trowels, etc; – production of footwear – soles and other elastic details of household, sports and special footwear; – electrical engineering – flexible connectors, wire insulation, etc; – plumbing – seals, corrugated flexible hoses, etc.; – medical industry – flexible and rigid containers, medical tubes, infusion and transfusion systems, elements of laboratory equipment. In the medical field SEBS is actively used as a substitute for traditional polymeric materials, which have been used during many years and have many disadvantages

Lifelong Learning in the System of Higher Education: the State of the Problem and the Strategy of Integrating Educational Activities and Research

The authors of this article consider the current situation of lifelong learning education in leading Russian universities and define some possible strategies for integrating scientific research with educational activities. The empirical bases were: 1) statistical data on the activities of educational institutions of higher education (N = 1180), 2) dataset of monitoring the activities of universities participating in the federal academic leadership programme “Priority-2030”, 3) dataset of a survey of heads of centers for further vocational education in Russian universities (N = 450) as part of the Project “Monitoring of education markets and organizations (MEMO)”. The authors identified strategies for combining scientific and educational activities for lifelong learning programs at universities in the interests of the development of individual consumers, enterprises and branches of the national economy. The authors also found that universities take into account the social needs of society and the preferences of employers, but to a very small extent focus on transforming their scientific results into a new educational product for mass consumers. The significant focus of universities on research activities to a certain extent hinders the development and launch of new education programs, however, it is a group of research universities that demonstrates a higher cost of programs sold. The authors consider, how universities can be focused on working with the population or industry enterprises, integrating the research results into the modules of education programs, and stimulating an increase in the number of teachers combining research and teaching activities, at realizing the third University’s mission and taking into account the research grant volume