Anomalous superconducting proximity effect and coherent charge transport in semiconducting thin film with spin-orbit interaction

We present a microscopic theory of the superconducting proximity effect in a semiconducting thin film with spin-orbit interaction ($N_{SO}$) in an external magnetic field. We demonstrate that an effective 1D Hamiltonian which describes induced superconductivity in $N_{SO}$ in contact with a usual $s$-wave superconductor possesses not only spin-singlet induced superconducting order parameter term, as commonly adopted, but spin triplet order parameter term also. Using this new effective Hamiltonian we confirm previous results for a normal current across contacts of $N_{SO}$ with a normal metal and for a Josephson current with the same $N_{SO}$ with induced superconductivity, obtained previously in the framework of the phenomenological Hamiltonian without spin-triplet terms. However, a calculated current-phase relation across the transparent contact between $N_{SO}$ with induced superconductivity in magnetic field and usual $s$-wave superconductor differs significantly from previous results. We suggest the experiment which can confirm our theoretical predictions.Comment: 5 pages, 6 figure

Andreev reflection and strongly enhanced magnetoresistance oscillations in GaInAs/InP heterostructures with superconducting contacts

We study the magnetotransport in small hybrid junctions formed by high-mobility GaInAs/InP heterostructures coupled to superconducting (S) and normal metal (N) terminals. Highly transmissive superconducting contacts to a two-dimensional electron gas (2DEG) located in a GaInAs/InP heterostructure are realized by using a Au/NbN layer system. The magnetoresistance of the S/2DEG/N structures is studied as a function of dc bias current and temperature. At bias currents below a critical value, the resistance of the S/2DEG/N structures develops a strong oscillatory dependence on the magnetic field, with an amplitude of the oscillations considerably larger than that of the reference N/2DEG/N structures. The experimental results are qualitatively explained by taking Andreev reflection in high magnetic fields into account.Comment: 5 pages, 5 figure

Andreev reflection and enhanced subgap conductance in NbN/Au/InGaAs-InP junctions

We report on the fabrication of highly transparent superconductor/normal metal/two-dimensional electron gas junctions formed by a superconducting NbN electrode, a thin (10nm) Au interlayer, and a two-dimensional electron gas in a InGaAs/InP heterostructure. High junction transparency has been achieved by exploiting of a newly developed process of Au/NbN evaporation and rapid annealing at 400C. This allowed us to observe for the first time a decrease in the differential resistance with pronounced double-dip structure within the superconducting energy gap in superconductor-2DEG proximity systems. The effect of a magnetic field perpendicular to the plane of the 2DEG on the differential resistance of the interface was studied. It has been found that the reduced subgap resistance remains in high magnetic fields. Zero-field data are analyzed within the previously established quasiclassical model for the proximity effect.Comment: 15 pages, 5 figure

СТРАТЕГИЧЕСКОЕ ПЛАНИРОВАНИЕ КАК ИНСТРУМЕНТ СТРАТЕГИЧЕСКОГО УПРАВЛЕНИЯ РЕГИОНАЛЬНОЙ СОЦИАЛЬНО-ЭКОНОМИЧЕСКОЙ СИСТЕМОЙ

Existing technologies for the management and organization of effective functioning of economy and social sphere of regional socio-economic systems do not give the expected results. The reasons are many, but the main ones are the lack of modern management techniques and methodological tools that enable the regions to realize their benefits. Many of the problems inherent in the region may be effectively solved using methods of strategic management and strategic planning. The importance of using these methods in combination is that it is possible to arrange the sustainable development of the industries of the region, effectively to realize its potential, to off set the unevenness of their development, to coordinate the interaction of all participants of the regional socio-economic system.Существующие технологии управления и организации эффективного функционирования экономики и социальной сферы региональной социально-экономической системы не дают ожидаемых результатов. Причин много, но основными являются отсутствие современных методов управления, а также методических инструментов, позволяющих регионам реализовать свои преимущества. Многие проблемы, присущие регионам можно эффективно решить, используя методы стратегического управления и стратегического планирования. Важность использования этих методов в их сочетании заключается в том, что появляется возможность организовать устойчивое развитие отраслей экономики региона, эффективно реализовать его потенциал, нивелировать неравномерность их развития, скоординировать взаимодействие всех участников региональной социально-экономической системы

Double proximity effect in hybrid planar Superconductor-(Normal metal/Ferromagnet)-Superconductor structures

We have investigated the differential resistance of hybrid planar Al-(Cu/Fe)-Al submicron bridges at low temperatures and in weak magnetic fields. The structure consists of Cu/Fe-bilayer forming a bridge between two superconducting Al-electrodes. In superconducting state of Al-electrodes, we have observed a double-peak peculiarity in differential resistance of the S-(N/F)-S structures at a bias voltage corresponding to the minigap. We claim that this effect (the doubling of the minigap) is due to an electron spin polarization in the normal metal which is induced by the ferromagnet. We have demonstrated that the double-peak peculiarity is converted to a single peak at a coercive applied field corresponding to zero magnetization of the Fe-layer

ПУТИ И ФАКТОРЫ, ОБЕСПЕЧИВАЮЩИЕ ПЕРЕХОД ЭКОНОМИКИ СУБЪЕКТОВ МАКРОРЕГИОНА НА НОВЫЙ ТЕХНОЛОГИЧЕСКИЙ УКЛАД

Purpose: the purpose of the article is to study the state of technological structures of the subjects of the macroregion, to determine the factors influencing its formation and development, to justify the ways of modernization of technological development.Methods: the methodological base of the research is based on the use of a systematic approach and General scientific methods: scientific abstraction, analysis and synthesis, generalization, system-structural analysis.Results: the analysis of the state of technological structures of the studied macroregion is carried out, the dominant structures are identified, the factors, among which are investments, commissioning of fixed assets and the level of education, which influence the formation and development of the technological structure, are considered. The direct correlation of the increasing level of technological structure with the increase of the educational level of the employed in the economy is revealed. The possible ways of technological development modernization for the macroregion are determined on the basis of the selection of the catching-up and advanced development strategy.Conclusions and Relevance: the main result of the research is the conclusion that the knowledge of the state of the technological structure of the region will allow to outline the strategy of its development, that the high educational level of the employed in the economy and social sphere will allow the region to move more rapidly to a higher technological structure. The implementation of the catch-up and advanced development strategy is designed to implement technological innovations that should lead to increased productivity, renewal of fixed capital and competitiveness, which will change the structure of the economy, to determine the most important areas of its modernization.Цель: Цель статьи состоит в исследовании состояния технологических укладов субъектов макрорегиона, определении факторов, влияющих на его формирование и развитие, и в обосновании путей модернизации технологического развития.Методология проведения работы: Методологическая база исследования основана на использовании системного подхода и общенаучных методов: научной абстракции, анализа и синтеза, обобщения, системно-структурного анализа.Результаты работы: Проведен анализ состояния технологических укладов изучаемого макрорегиона, выявлены доминирующие уклады, рассмотрены факторы, в число которых входят инвестиции, ввод в действие основных фондов и уровень образования, оказывающие влияние на формирование и развитие технологического уклада. Выявлена прямая корреляция возрастания уровня технологического уклада с повышением образовательного уровня занятых в экономике. Определены возможные для макрорегиона пути модернизации технологического развития на основе выбора стратегии догоняющего и опережающего развития. Выводы: Основным итогом работы является вывод о том, что знание состояния технологического уклада региона позволит наметить стратегию его развития, что высокий образовательный уровень занятых в экономике и социальной сфере позволит региону более быстрыми темпами перейти на более высокий технологический уклад. Реализацию стратегии догоняющего и опережающего развития призваны осуществить технологические инновации, которые должны привести к росту производительности труда, обновлению основного капитала и повышению конкурентоспособности, что позволит изменить структуру экономики, определить наиболее важные направления ее модернизации

Supercurrent in Nb/InAs-Nanowire/Nb Josephson junctions

We report on the fabrication and measurements of planar mesoscopic Josephson junctions formed by InAs nanowires coupled to superconducting Nb terminals. The use of Si-doped InAs-nanowires with different bulk carrier concentrations allowed to tune the properties of the junctions. We have studied the junction characteristics as a function of temperature, gate voltage, and magnetic field. In junctions with high doping concentrations in the nanowire Josephson supercurrent values up to 100\,nA are found. Owing to the use of Nb as superconductor the Josephson coupling persists at temperatures up to 4K. In all junctions the critical current monotonously decreased with the magnetic field, which can be explained by a recently developed theoretical model for the proximity effect in ultra-small Josephson junctions. For the low-doped Josephson junctions a control of the critical current by varying the gate voltage has been demonstrated. We have studied conductance fluctuations in nanowires coupled to superconducting and normal metal terminals. The conductance fluctuation amplitude is found to be about 6 times larger in superconducting contacted nanowires. The enhancement of the conductance fluctuations is attributed to phase-coherent Andreev reflection as well as to the large number of phase-coherent channels due to the large superconducting gap of the Nb electrodes.Comment: 5 Figure, submitted to Journal of Applied Physic

Numerical model of hybrid mode-locked Tm-doped all-fibre laser

Abstract: Ultrafast Tm-doped fibre lasers have been actively studied for the last decade due to their potential applications in precise mid-IR spectroscopy, LIDARs, material processing and more. The majority of research papers is devoted to the comparison between a numerical modelling and experimental results; however, little attention is being paid to the comprehensive description of the mathematical models and parameters of the active and passive components forming cavities of Tm-doped all-fibre lasers. Thus, here we report a numerical model of a stretched-pulsed Tm-doped fibre laser with hybrid mode-locking and compare it with experimental results. The key feature of the developed numerical model is employment of the experimentally measured dispersion coefficients and optimisation of some model parameters, such as the bandwidth of the spectral filter spectral filtering and the saturation power of the active fibre, for a conformity with the experiment. The developed laser emits 331.7 fs pulses with a 23.8 MHz repetition rate, 6 mW of average power, 0.25 nJ of pulse energy, and a 21.66 nm spectral bandwidth at a peak wavelength of 1899.5 nm. The numerical model characteristics coincide with experimentally achieved spectral width, pulse duration, and average power with inaccuracy of 4.7%, 5.4%, and 22.9%, respectively. Moreover, in the discussion of the work the main possible reasons influencing this inaccuracy are highlighted. Elimination of those factors might allow to increase accuracy even more. We show that numerical model has a good agreement with the experiment and can be used for development of ultrafast Tm-doped fibre laser systems