Interplay between spin-relaxation and Andreev reflection in ferromagnetic wires with superconducting contacts

We analyze the change in the resistance of a junction between a diffusive ferromagnetic (F) wire and normal metal electrode, due to the onset of superconductivity (S) in the latter and a double Andreev scattering process leading to a complete internal reflection of a large fraction of the spin-polarized electrons back into the ferromagnet. The superconducting transition results in an additional contact resistance arising from the necessity to match spin-polarized current in F-wire to spin-less current in S-reservoir, which is comparable to the resistance of a piece of a F-wire with the length equal to the spin-relaxation length.Comment: 4 pages, 2 fig

Phase separation on microtubules: from droplet formation to cellular function?

Microtubules are cytoskeletal polymers that play important roles in numerous cellular processes, ranging from the control of cell shape and polarity to cell division and intracellular transport. Many of these roles rely on proteins that bind to microtubule ends and shafts, carry intrinsically disordered regions, and form complex multivalent interaction networks. A flurry of recent studies demonstrated that these properties allow diverse microtubule-binding proteins to undergo liquid–liquid phase separation (LLPS) in vitro. It is proposed that LLPS could potentially affect multiple microtubule-related processes, such as microtubule nucleation, control of microtubule dynamics and organization, and microtubule-based transport. Here, we discuss the evidence in favor and against the occurrence of LLPS and its functional significance for microtubule-based processes in cells

Theoretical investigation of controlled generation of a dense attosecond relativistic electron bunch from the interaction of an ultrashort laser pulse with a nanofilm

For controllable generation of an isolated attosecond relativistic electron bunch [relativistic electron mirror (REM)] with nearly solid-state density, we propose using a solid nanofilm illuminated normally by an ultraintense femtosecond laser pulse having a sharp rising edge. With two-dimensional (2D) particle-in-cell (PIC) simulations, we show that, in spite of Coulomb forces, all of the electrons in the laser spot can be accelerated synchronously, and the REM keeps its surface charge density during evolution. We also developed a self-consistent 1D theory, which takes into account Coulomb forces, radiation of the electrons, and laser amplitude depletion. This theory allows us to predict the REM parameters and shows a good agreement with the 2D PIC simulations.open524

Magnetic field influence on the proximity effect in semiconductor - superconductor hybrid structures and their thermal conductance

We show that a magnetic field can influnce the proximity effect in NS junctions via diamagnetic screening current flowing in the superconductor. Using ballistic quasi-one-dimensional (Q1D) electron channels as an example, we show that the supercurrent flow shifts the proximity-induced minigap in the excitation spectrum of a Q1D system from the Fermi level to higher quasiparticle energies. Thermal conductance of a Q1D channel (normalized by that of a normal Q1D ballistic system) is predicted to manifest such a spectral feature as a nonmonotonic behavior at temperatures corresponding to the energy of excitation into the gapful part of the spectrum.Comment: 5 pages, 3 figures, revised version with a new titl

The optimality of the option of abolishing serfdom in Russia, implemented in 1861

The article discusses the controversial issues related to the abolition of serfdom in Russia in 1861: its causes, features of preparation and implementation. The authors focus on the question of whether the implemented version of the abolition of serfdom in Russia was optimal. For this purpose, a comparative analysis of the abolition of serfdom in Russia is carried out with similar reforms in European countries, which could serve as a reference point, primarily in Austria and Prussia. It is concluded that the peasant reform in Russia in 1861 (in the final version) was carried out primarily in the interests of the state and not of individual social groups (landowners and peasants). It is the state that has benefited most from the implementation of this particular version of the reform, both financially and politically. Among the losers there were both peasants (to a greater extent) and landowners (to a lesser extent). The main thing was that the reform provoked the problem of the lack of land of the majority of peasants, which in the future became one of the main reasons for the social explosion and revolutions at the beginning of the XX century

RBS-channeling study of radiation damage in Ar+ implanted CuInSe2 crystals

Chalcopyrite solar cells are reported to have a high tolerance to irradiation by high energy electrons or ions, but the origin of this is not well understood. This work studies the evolution of damage in Ar + -bombarded CuInSe 2 single crystal using Rutherford backscattering/channeling analysis. Ar + ions of 30 keV were implanted with doses in the range from 10 12 to 3 × 10 16 cm -2 at room temperature. Implantation was found to create two layers of damage: (1) on the surface, caused by preferential sputtering of Se and Cu atoms; (2) at the layer of implanted Ar, possibly consisting of stacking faults and dislocation loops. The damage in the second layer was estimated to be less than 2% of the theoretical prediction suggesting efficient healing of primary implantation defects

Scattering of scalar and Dirac particles by a magnetic tube of finite radius

We consider the Dirac equation in cylindrically symmetric magnetic fields and find its normal modes as eigenfunctions of a complete set of commuting operators. This set consists of the Dirac operator itself, the $z$-components of the linear and the total angular momenta, and of one of the possible spin polarization operators. The spin structure of the solution is completely fixed independently of the radial distribution of the magnetic field which influences only the radial modes. We solve explicitly the radial equations for the uniform magnetic field inside a solenoid of a finite radius and consider in detail the scattering of scalar and Dirac particles in this field. For particles with low energy the scattering cross section coincides with the Aharonov-Bohm scattering cross section. We work out the first order corrections to this result caused by the fact that the solenoid radius is finite. At high energies we obtain the classical result for the scattering cross section.Comment: LaTeX file, 17 page

FEATURES OF TESTING THE HIGH-TEMPERATURE THERMAL FIRE DETECTORS

The article discusses the features of tests to determine the response temperature, inertia and resistance to elevated temperatures of thermal fire detectors with response temperature over 160 ºС, that is, belonging to class H according to GOST 34698–2020 “Fire Detectors. General technical requirements. Test methods”. It is noted that tests to determine the resistance of high-temperature fire detectors to elevated temperatures should be carried out in two stages, since such detectors, as a rule, are two-component, consisting of a sensitive element and a processing unit. These components have different elevated temperature limits, indicated in the technical documentation for specific types of detectors, at which their functionality remains intact. It was concluded that it is necessary to amend the current edition of GOST 34698–2020