The Coulombic effect on microwave-induced electron heating in a 2D electron gas on liquid helium under quantizing magnetic field is theoretically studied. An extension of the linewidth of the intersubband resonance which takes into account squeezing of the electron density of states into Landau levels and strong internal electric fields of fluctuational origin is proposed. This approximation results

The escape rate of S → R switching (from superconducting S state to resistive R state) in Josephson junction formed by s-wave single-band (SB) and three-band (ThB) superconductors (SB/ThB junctions) in macroscopic quantum tunneling regime is investigated. We use the effective critical current approximation in SB/ThB junctions. It was shown that escape rate can exhibit qualitative features in the case

We considered a nanoelectromechanical system consisting of a movable Cooper-pair box qubit, which is subject to an electrostatic field, and coupled to the two bulk superconductors via tunneling processes. We suggest that qubit dynamics is related to that of a quantum oscillator and demonstrate that a bias voltage applied between superconductors generates states represented by the entanglement of qubit

Influence of the external electric field and the external strain on a quantum paramagnetic insulator is studied. It is shown that the external electric field and/or strain can cause drastic changes in the magnetic characteristics of the paramagnet.

The transmission coefficient T of the Dirac quasielectrons through a rectangular potential barrier in the α-T3 model is calculated and analyzed in the continuum approach. The dependence of the transmission rate on para-meter α, which characterizes the degree of coupling of the central atom with the atoms in the vertices of the hexagonal lattice, and parameter β, which is equal to the ratio of Fermi

The long-term stability of well-known TVO sensors before and after gamma irradiation was investigated during almost 17 years. Five of six sensors, calibrated in the temperature range from 3 to 300 K, were selected according to a requirement of their relative accuracy ΔT/T ≤ ± 0.25% at the cryogenic temperature range. Long-term stability measurements made 7.5 years after calibration are in good agreement

We calculate the extremal cross-sectional areas and cyclotron masses for the Fermi-surface pockets in Dirac and Weyl topological semimetals. The calculation is carried out for the most general form of the electron energy bands in the vicinity of the Weyl and Dirac points. Using the obtained formulas, one can find parameters characterizing the Dirac and Weyl electrons in the topological semimetals from

IR absorption spectra of 1-butanol isolated in an argon matrix were obtained at temperatures from 10 to 50 K. The conformational behavior of 1-butanol was analyzed using the results of quantum-chemical simulation of the structure and vibrational spectra of its small clusters. We studied the conformational composition of 1-butanol in matrix isolation and showed the transformation of its structure that

We employ low-temperature matrix-isolation FTIR spectroscopy and quantum chemical calculations to study the interaction between nucleobase uracil and coronene which models the graphene surface. To observe the dimer FTIR spectrum, we use a quartz microbalance that allows us to produce matrix samples with precisely determined concentrations of coronene and uracil (with the concentration ratio of 2.5:1:1000

The main features of the secondary emission mass spectrometry probing of condensed systems containing compounds of biological significance at low temperatures are summarized. The possibilities of distinguishing mass spectra of the solid and liquid phases of simple organic compounds and water as the medium for bio-molecules, monitoring of phase transitions and nonequilibrium processes are illustrated

Based on the self-consistent Hartree–Fock approximation, the nonstationary equation is obtained for the one-particle wave function describing the Bose–Einstein condensate in a rarefied gas of spin-zero bosons. A rarefied gas of bosons is exposed to the static external field, which ensures its finite ground state. The derived equation allows one to correctly determine the ground state energy in the

The application of various action spectroscopy and absorption spectroscopy methods for studying the structure of biological molecules and their constituent fragments in an isolated state is considered. The main attention is paid to the results achieved in the study of the nucleosides which are the structural units of DNA and RNA. It has been demonstrated that modern low-temperature spectroscopy methods

The biological molecules delivered to Earth on the board of meteorites and comets were called one of the possible causes of the origin of life. Therefore, our understanding of the routes of formation of biomolecules in space should shed a light on the possibility of the existence of habitable extrasolar planets. The large abundance of organic molecules is found in the space regions with the lowest

Noncovalent interaction between semiconducting single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) in composite films (GO-SWNTs) was analyzed by Raman spectroscopy in the range of D and G modes (1170–1780 cm−1). Comparison between Raman spectra of composite film and single-component GO and SWNTs films showed that the interaction between GO and SWNTs is accompanied by a band broadening and

The possible role of molecular products of cell radiolysis, in particular, hydrogen peroxide molecules, in blocking DNA activity in cancer cells during irradiation with heavy ions is investigated. It is supposed that hydrogen peroxide molecules can form long-lived molecular complexes with DNA atomic groups and, thus, prevent the realization of genetic information in the biological cells. Using the

The ferromagnetic resonance (FMR) spectra of Fe3O4 and ZnFe2O4 nanoparticles with organic synthesis products were studied at T = 4.2 K. It was determined that the sintering of nanoparticles induced by postsynthesis heat treatment forms a mechanically unstable transition layer between them. Changes in the FMR spectra of Fe3O4 nanoparticles synthesized by precipitation in microemulsions using octylphenol

The optical absorption, fluorescence, phosphorescence in UV and visible spectral range, and effect of light irradiation on spectral properties of DNA with the presence of nickel ions are studied. The quantity of nickel ions varies from 1 ion per 500 base pairs of DNA to 2 ions per base pair. Three important features fixed: the shape of fluorescence and phosphorescence spectra of the DNA do not change

Original fundamental properties of Yanson point contacts allow their application to research and technology development at a wide range of surrounding conditions. At low temperature these nanoobjects can be used as a main instrument of Yanson point-contact spectroscopy. At room temperature they can serve as a sensitive element of advanced nanosensors with excellent performance. The most important advantage

Computer simulations of an argon fcc crystal fragment with embedded water clusters of different sizes are performed using the quantum mechanical DFT/M06-2X method. The effect of the argon matrix on the structural, energy, and spectral parameters of individual water clusters are investigated. The formation energies of (H2O)n@Arm complexes, as well as deformation energies of water clusters and of the

A feature of biological systems is their high structural heterogeneity. This is manifested in the fact that the processes observed at the nanoscopic level are noticeably multistage in time. The paper expounds an approach that allows, basing on the methods of nonequilibrium statistical mechanics, to obtain kinetic equations that enable describing the evolution of slow processes occurring against the

Within the framework of the theory of strongly-interacting quantum Bose liquids, we consider a general relativistic model of self-interacting complex scalar fields with logarithmic nonlinearity taken from dense superfluid models. We demonstrate the existence of gravitational equilibria in this model, described by spherically symmeric nonsingular finite-mass asymptotically-flat solutions. These equilibrium

The temperature dependences of resistance of n-type conductivity Bi2Se3 whiskers with doping concentration (1–2)⋅1019 cm−3 were studied in the temperature range 1.6–300 K. The sharp drop of the resistance was detected that is a result of a partial transition to the superconductive state at the critical temperature Tc = 5.3 K and probably due to the inclusion of β-PdBi2 phase in the studied samples

An observed correlation between the critical temperature of a superconducting transition in high-temperature superconductors and a proximity of their electronic structure to the topological Lifshitz transition needs to be verified on simple model materials. Here we show that such an object could be a Mo–Re alloy with an equal concentration of constituent elements. We present new evidence of the presence

For the first time, studies of the temperature dependences of the thermoelectric power for various compositions of Bi2Sr2CaxZn1−xCu2O8+y (x = 1; 0.8; 0.4) in the range 77–320 K have been carried out. The obtained experimental results are analyzed within the framework of the Xin’s two-band model. The concentration of holes per copper atom and the band gap of the semiconductor type Bi–O layers are determined

For the first time, the temperature dependences of the electrical resistivity ρ(T) were studied in GdxPb1−xMo6S8 (x = 0.5, 0.7, 0.9) compounds in the temperature range 4–18 K and magnetic fields up to 14 T. It is shown that the superconducting transition temperature values Tc decrease from 14.6 K for a compound with x = 0.5 to 11.8 K for x = 0.9. Experimental dependences Hc2(T) were plotted and it

Ideal Bose-gas with finite particle number N is investigated. It is shown that the well-known Bose–Einstein distribution of particles over their quantum states consists of two terms — Bose–Einstein term and an additional N-dependent one. The statement that the chemical potential of the ideal Bose-gas should be negative requires to be also corrected. It is obtained that the analytically calculated observables

The Monte Carlo method was used to calculate the relative dispersions of the magnetization Rm, susceptibility Rχ, and heat capacity RC for a weakly diluted impurity Potts model with the number of spin states q = 4. It is shown that the introduction of disorder in the form of nonmagnetic impurities into the two-dimensional Potts model with q = 4 on square lattice leads to nonzero values for Rm, Rχ,

Electric, piezoelectric, and elastic characteristics of the orthorhombic quantum paramagnet are calculated. Using the exact analytical solution it was shown that the electric permittivity, piezoelectric, and elastic modules can manifest strong dependences on the values of the external magnetic, electric field, external strain, and temperature.

The ballistic transmission of the Dirac ultrarelativistic quasielectrons in graphene structures with the rectangular potential barrier is considered, and both the single and the double-barrier structures are analyzed. Within the framework of the continuum model, the transmission coefficient of quasielectrons T is calculated depending on the parameters of the problem. It is believed that there is an

The dependences of electrical conductivity, the Hall coefficient, the Seebeck coefficient, thermoelectric power factor and microhardness of Bi2Se3 polycrystals on the degree of deviation from stoichiometry 59.9–60.0 at. % Se and temperature (77–300 K) were obtained. The samples exhibited n-type conductivity in the studied ranges of compositions and temperatures. The boundaries of the Bi2Se3 homogeneity

Using the models of elastic and dielectric continuum, the system of differential equations is obtained, the exact analytical solutions of which describe the elastic displacement of the medium for nitride-based semiconductor nanostructure and the piezoelectric effect, which is caused by shear acoustic phonons. The theory of the shear acoustic phonons spectrum caused by the piezoelectric potential was

Evolution of the nonequilibrium inhomogeneities and topological defects is studied in terms of complex kink solutions of the sine–Gordon equation. The weakly damped oscillation of the sine–Gordon kink, named as the kink quasimode, is described explicitly. It is shown that the oscillatory kink behavior and the wave packet generation depend significantly on the initial nonequilibrium kink profile. In

The effect of high hydrostatic pressure up to 12 kbar on the electrical resistivity in the basal ab plane of an optimally doped Y0.77Pr0.23Ba2Cu3O7−δ single crystal was studied. An inhomogeneity of the sample is found that does not depend on the applied pressure, P. The Tc(P) dependence increases nonlinearly with increasing P, and the value of the baric derivative, dTc/dP, decreases. Possible mechanisms

It is shown that the experimental data on the temperature dependences of the effective electrical resistance and thermal conductivity in the range of 4.2–300 K of the electroconsolidated Fe0.5Ni0.5 composite are within the Hashin–Shtrikman boundaries for the conductivities of a three-phase system. The components of the system are pure Fe and Ni, and the intergranular medium in the form of an alloy

The optical properties of C60 single crystals, intercalated with nitrogen molecules, were studied by the spectral-luminescence method at a temperature T = 30 K and excitation by the He–Ne laser (Eexc = 1.96 eV). Intercalation was carried out at a pressure of 30 atm in a temperature range of 200–550 °C. It was found that at sorption temperatures up to 400 °C, the bands of the low-temperature luminescence

We present an experimental study of the thermo emf of a two-dimensional electron-hole system in a 21 nm HgTe quantum well in the presence of magnetic field. The first experimental observation of Nernst-Ettingshausen effect in a 2D semimetal is reported. The comparison between theory and experiment shows that the thermo emf is determined by two contributions: the diffusion and the phonon drag, with

Quasiclassical calculations of the effective cyclotron mass and the spectrum of Landau levels have been carried out for carriers of the size-quantized H2 subband with a nonmonotonic dispersion law, which forms a valence band of 20.5-nm-wide HgTe quantum well with an inverted band structure. The model of the so-called “extremum loop”, previously developed by Rashba and Sheka for semiconductors with

The longitudinal ρxx(B, T) and Hall ρxy(B, T) resistances are experimentally investigated in n-InGaAs/GaAs nanostructures with a single and double quantum wells in the magnetic field range B = 0–2.5 T and temperatures T = 1.8–20 K. It is shown that the origin of the temperature-independent point located at ω c τ ≅ 1 on the ρxx(B, T) curves is due to the combined action of the classical cyclotron motion

The peculiarity of planar quantum magnetotransport in the type II broken-gap p-GaInAsSb/p-InAs heterostructures at high magnetic fields has been investigated. The structure of the hybridized energy spectrum of a two-dimensional semimetal channel at a single type II broken-gap heterointerface was considered in dependence on the composition of the quaternary solid solution. A transition from a conducting

The phase and elemental compositions and galvanomagnetic properties (4.2 K ≤ T ≤ 300 K, B ≤ 0.07 T) of samples from a single-crystal Pb1−x−ySnxNiyTe ingot (x = 0.08, y = 0.01) synthesized by the Bridgman–Stockbarger method were studied. Microscopic inclusions enriched in nickel were found. It is shown that in the main phase, the tin concentration increases exponentially along the ingot (x = 0.06–0

The impurity absorption in Zn1−xMnxO is formed by dipole allowed p-s transitions from deep antibonding p-d hybrid (pdh) state to the conduction band. In this paper, photoluminescence of Zn1−xMnxO single crystals was investigated in the temperature range of 7–340 K at laser excitation with the energy of 3.06 eV. Intensive photoluminescence band was observed in the energy region of 2.40–1.6 eV with the

We present experimental data on the synthesis and investigation of the superconducting and structural properties of organometallic fullerides M(3−n)(NR4)(n)C60, where M = K, Rb; R = hydrogen H, deuterium D, methyl Me, ethyl Et, butyl Bu; n = 1, 2, 3, synthesized by exchange reactions of homofullerides of alkali metals of composition K3C60 and Rb3C60 with ammonium halides in the medium of absolute toluene

The paper provides experimental data on the synthesis and study of the superconducting properties of potassium and rubidium heterofullerides modified by Wood’s alloy — Sn, Pb, Bi, Cd (hereinafter W) with a melting temperature Tm = 61.5 °C or Y alloy — Bi, Sn, Pb, In, Cd, Tl with Tm = 41.5 °C. The synthesis of heterofullerides was carried out by the interaction of fullerides of the composition K2C60

The field dependence of Hall resistivity ρH and magnetization M of the magnetocaloric Ni50Mn35Sb15−xGex (x = 0, 1, 3) alloys were measured at T = 4.2 K and in magnetic fields of up to 70 kOe. The martensitic transitions temperatures, i.e., the martensite start temperature MS, martensite finish temperature MF, austenite start AS and austenite finish AF temperatures, were obtained from the magnetization

The electro- and magneto-transport as well as magnetic properties of Co2MeSi (Me = Ti, V, Cr, Mn, Fe, Co, Ni) Heusler alloys were studied. The electroresistivity was measured from 4.2 to 300 K, the galvanomagnetic properties (magnetoresistivity and Hall effect) were measured at T = 4.2 K in magnetic fields of up to 100 kOe, and the magnetization at T = 4.2 and 300 K in fields of up to 70 kOe. The normal

The field dependence of magnetization at T = 4.2 K and in magnetic fields of up to 70 kOe, temperature dependences of magnetization (2 K < T < 300 K), heat capacity (2 K < T < 30 K) and magnetic susceptibility (2 K < T < 1000 K) for Mn1.99Co0.96Al1.05 and Mn1.79Co1.25Al0.96 alloys, closed in composition to the Mn2CoAl spin gapless semiconductor, were studied. Alloys studied were demonstrated to be

Vertical hole transport in single-crystalline diamond films with ohmic and Schottky contacts was studied at dc and pulsed electric fields up to ∼ 5⋅105 V/cm. Conductivity mechanisms at different fields were identified. The concentrations of free carriers (holes) and acceptors were determined. The hole recombination time at boron acceptors has been estimated. The mechanisms of electric field ionization

Ytterbium and holmium titanates have been synthesized and their dielectric and magnetic properties have been investigated. The frequency dependences of the permittivity at T = 77 and 300 K, and measured magnetization curves and temperature dependences of the magnetic susceptibility in fields up to 30 kOe and at temperatures from 2 K to 50 K have been obtained. The properties of the doped and undoped

Spin dynamics in spiral magnetic structures has been investigated. It has been shown that the internal spatially dependent magnetic field in such structures produces a new mechanism of spin relaxation.

Electron paramagnetic resonance (EPR) is a well-established spectroscopic technique for electronic structure characterization of rare-earth ion impurities in crystalline and amorphous hosts. EPR spectra of erbium-doped glass matrices and nanocomposites can provide information about local structure variations induced by changes in chemical composition or crystallization processes. Characterization possibilities

Original results on the EPR and photoluminescence Cr3+ ions in natural magnesium aluminum spinel (MgAl2O4) are presented. The photoluminescence spectra of Cr3+ ions in natural MgAl2O4 have been measured before and after irradiated by fast neutrons.

The electronic structure of Mn2+ ion substituted for the host Y atom in orthorhombic bulk YAlO3 crystals has been calculated by means of hybrid exchange-correlation functional HSE within density functional theory. The supercell approach has been used to simulate in Pbnm YAlO3 crystal the point defects, Mn-dopant and compensated the F+ center (oxygen vacancy with one trapped electron), to make unit

The efficiency of stabilization of H centers as well as its dependence on the degree of uniaxial deformation are considered within the framework of the modified geometric model of alkali halides. It is shown that stabilization of H centers is difficult in KI and RbI crystals, while in other NaCl-type crystals it becomes quite probable. Under uniaxial deformation, the interstitial space, in which the

Atomically smooth (001) surfaces of SrTiO3 cut from the high-quality single crystals at two different miscut angles 0.9 and 7.0 deg between the real flat surfaces and crystallographic planes (001) were analyzed by means of the reflection high energy electron diffraction (RHEED) method from the room down to liquid helium temperatures. The diffraction patterns typical of the RHEED geometry close to ideal

The luminescent properties of Ca3TaGa3Si2O14 (CTGS, catangasite) single crystals have been studied by means of the vacuum ultraviolet excitation spectroscopy utilizing synchrotron radiation from 1.5 GeV storage ring of MAX IV synchrotron facility. Two emission bands at 320 nm (3.87 eV) and 445 nm (2.78 eV) have been detected. Examining excitation spectra in vacuum ultraviolet spectral range, the 320 nm

The first-principles (ab initio) computations of the structural, electronic, and phonon properties have been performed for cubic and low-temperature tetragonal phases of BaTiO3 and SrTiO3 perovskite crystals, both stoichiometric and non-stoichiometric (with neutral oxygen vacancies). Calculations were performed with the CRYSTAL17 computer code within the linear combination of atomic orbitals approximation

Photoluminescence and excitation spectra of ScF3 single crystals have been measured under vacuum ultraviolet excitations utilizing undulator synchrotron radiation from 1.5 GeV storage ring of MAX IV synchrotron. The emission peak at 280 nm is explained as emission band of self-trapped excitons in ScF3. This emission is quenched at 50 K and activation energy of thermal quenching was obtained. The excitation

The influence of thermal disorder and static distortions on the local structure in microcrystalline solid solutions of tungstates ZncNi1−cWO4 with c = 0.0−1.0 was investigated using temperature-dependent (10–300 K) x-ray absorption spectroscopy (XAS) at the W L3-edge. In addition, the vibrational properties of the solid solutions were studied by Raman spectroscopy. Our results indicate that the formation

We report the results of ab initio calculations and analysis of systematic trends for the F centers in the bulk and on the (001) surface in oxide perovskites, such as BaTiO3, SrTiO3, SrZrO3, and PbZrO3, with a corresponding comparison of the F centers in perovskites with those in alkaline earth metal fluorides (CaF2, BaF2, and SrF2). It was found that in perovskites in both bulk F centers and those

Synchrotron radiation is applied to study visible and UV luminescence spectra and their excitation spectra of undoped as well as In and Sb doped cadmium iodide crystals at 10 K. The origin of principal luminescence bands and the role of impurities in the formation of emission centers are discussed. The luminescence properties have been explained based on the electronic structure of CdI2 crystals.