Spin-polarized supercurrents for spintronics: a review of current progress

During the past 15 years a new field has emerged, which combines superconductivity and spintronics, with the goal to pave a way for new types of devices for applications combining the virtues of both by offering the possibility of long-range spin-polarized supercurrents. Such supercurrents constitute a fruitful basis for the study of fundamental physics as they combine macroscopic quantum coherence with microscopic exchange interactions, spin selectivity, and spin transport. This report follows recent developments in the controlled creation of long-range equal-spin triplet supercurrents in ferromagnets and its contribution to spintronics. The mutual proximity-induced modification of order in superconductor-ferromagnet hybrid structures introduces in a natural way such evasive phenomena as triplet superconductivity, odd-frequency pairing, Fulde-Ferrell-Larkin-Ovchinnikov pairing, long-range equal-spin supercurrents, $\pi$-Josephson junctions, as well as long-range magnetic proximity effects. All these effects were rather exotic before 2000, when improvements in nanofabrication and materials control allowed for a new quality of hybrid structures. Guided by pioneering theoretical studies, experimental progress evolved rapidly, and since 2010 triplet supercurrents are routinely produced and observed. We have entered a new stage of studying new phases of matter previously out of our reach, and of merging the hitherto disparate fields of superconductivity and spintronics to a new research direction: super-spintronics.Comment: 95 pages, 23 Figures; published version with minor typos corrected and few references adde

Statistical Mechanics and the Physics of the Many-Particle Model Systems

The development of methods of quantum statistical mechanics is considered in light of their applications to quantum solid-state theory. We discuss fundamental problems of the physics of magnetic materials and the methods of the quantum theory of magnetism, including the method of two-time temperature Green's functions, which is widely used in various physical problems of many-particle systems with interaction. Quantum cooperative effects and quasiparticle dynamics in the basic microscopic models of quantum theory of magnetism: the Heisenberg model, the Hubbard model, the Anderson Model, and the spin-fermion model are considered in the framework of novel self-consistent-field approximation. We present a comparative analysis of these models; in particular, we compare their applicability for description of complex magnetic materials. The concepts of broken symmetry, quantum protectorate, and quasiaverages are analyzed in the context of quantum theory of magnetism and theory of superconductivity. The notion of broken symmetry is presented within the nonequilibrium statistical operator approach developed by D.N. Zubarev. In the framework of the latter approach we discuss the derivation of kinetic equations for a system in a thermal bath. Finally, the results of investigation of the dynamic behavior of a particle in an environment, taking into account dissipative effects, are presented.Comment: 77 pages, 1 figure, Refs.37

METHODICAL APPROACH TO THE EVALUATION OF INVESTMENT PROJECTS IN OIL PRODUCTION IN CONDITIONS OF UNCERTAINTY AND RISKS

Development of oilfield is a long term capital-intensive investment project, which is characterized by incomplete and inaccurate information about conditions of its realization. Efficiency evaluation of license area development is impossible without accounting uncertainty associated with oil production. The article analyzes the current state of the Russian oil industry, highlights the main risks affecting the activities of oil companies. Classification of risks in the qualitative and quantitative characteristics is suggested. Methods of economic efficiency evaluation of investments in oil field development in new production regions are considered, the expediency of the fuzzy set theory application is shown. The task of expert systems building for efficiency evaluation of oil field development in terms of uncertainty in risks by investor is actualized. Scheme of an expert system for efficiency evaluation of oil field development using elements of theory of fuzzy sets is proposed

Broken time reversal of light interaction with planar chiral nanostructures

We report unambiguous experimental evidence of broken time-reversal symmetry for the interaction of light with an artificial nonmagnetic material. Polarized color images of planar chiral gold-on-silicon nanostructures consisting of arrays of gammadions show intriguing and unusual symmetry: structures, which are geometrically mirror images, lose their mirror symmetry in polarized light. The symmetry of images can be described only in terms of antisymmetry (black-and-white symmetry) appropriate to a time-odd process. The effect results from a transverse chiral nonlocal electromagnetic response of the structure and has some striking resemblance with the expected features of light scattering on anyon matter

Classification of Attacks in Simulation Studies of Complex Networks Vulnerabilities

The attacks generated while modeling degradation of network with complex structure have been classified. The results of the work might be useful in robustness analysis for model and real complex systems

Modeling of Aggregate Attacks on Complex Networks

An order factor in combinations of random and targeted attacks on modern scale free network model has been explored. Protection concepts based on timely restructuring of topologies have been discussed. Vulnerability parameter defined by investment value has been introduced, and protection financing strategies depending on node connectivity has been analyzed

Collaboration Strategies in Counteraction to Global Threats

Topology of information sharing networks in emergency situations and creation of stable relations between pertinent national and international agencies has been studied. Agent-based simulation model with competitive and collaborative actors has been developed to perform a quantitative analysis of interagency and international cooperation . It has been demonstrated a great value of action to support links between middle rank agents to counteract global threats effectively