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.

The electronic and atomic structure of a bulk 2D layered van-der-Waals compound CdPS3 was studied in the low (R3) and room (C2/m) temperature phases using first-principles calculations within the periodic linear combination of atomic orbitals method with hybrid meta exchange-correlation M06 functional. The calculation results reproduce well the experimental crystallographic parameters. The value of

The vibrational and luminescence properties of the TbAl3(BO3)4 single crystal were studied in the temperature range of 5–300 K. Raman spectra of the single crystal revealed 5 of 7 A1 and all E phonon modes predicted by the group-theory analysis. The splitting energy between the LO and TO components of polar E phonons is determined. A group of intense bands associated with the 5D4 → 7F0 electronic transition

The paper discusses the results of temperature studies of polymer-based nanocomposites obtained by incorporating multi-walled carbon nanotubes in thin layers of poly(3,4-ethylenedioxythophene):poly(4-styrenesulfonate), specifically focusing on interesting features in the dependencies of electrical properties across the wide range of temperatures from ambient one down to 10 K.

Photoluminescence and cathodoluminescence of LiF crystals doped with different binary metal oxides were measured in the wide temperature range of 50-300 K and time interval of 10−8−10−1 s after the nanosecond electron excitation pulse. Both as-grown those and crystals irradiated by an electron beam in range of absorbed dose up to 103 Gy were studied. It is shown that spectral-kinetic characteristics

Investigations of the propagation of the second sound waves were made in a resonator with the presence of a deuterium-helium gel. The technique was used in experiments for measuring the parameters of standing waves in the resonator in the presence or the absence of a gel. It is shown that the propagation of the second sound waves changes drastically in the presence of the gel: the attenuation of the

We study the temperature dependence of the in-plane magneto-resistance ρab(T) in the untwined YBa2Cu3O7−δ single crystals after irradiation by fast electrons (energy 0.5–2.5 MeV, dose 1018 cm−2), also with a small oxygen hypostoichiometry at different angles between the external magnetic field 15 kOe and the ab-planes α. We found that at high temperatures in the pseudogap region external magnetic field

A remarkable several times increase (up to 10 K) of the superconducting critical temperature Tc has been observed in point contacts created on the base of single crystals AFe2As2 (A = K, Cs, Rb). Possible reasons for such a Tc increase in point contacts are briefly discussed on a qualitative level. Among them, it is most likely attributed to interfacial carrier doping and/or uniaxial non-homogeneous

Magnetic proximity effect in multiband superconductor/ferromagnetic metal (S/F) structures was studied. Analytical solutions of the Usadel equations obtained for a number of limiting cases are applied in the case when the transport properties of both metals correspond to the diffusion type of conductivity. The induced (proximity) magnetic characteristics are shown to reflect the multiband structure

In the framework of the discrete self-trapped model and its generalizations, the dynamics of two nonlinear elements of different physical origin is considered. The influence on the dynamics of their own nonlinearity, various types of interaction nonlinearity and nonequivalence of subsystems is investigated. Exact solutions of dynamic equations are found and investigated. Particular attention is paid

Magnetic nano-particles are used in medicine both as medical means, and for the transport of medicines in the pathological area of an organism. Simultaneous influence on these particles of ultrasonic radiation and a constant magnetic field allows summarising a magnetic field of an nano-particles ensemble to the value, sufficient for its registration by the remote magnetic detector. The parity connecting

A detailed analysis of solutions to the Landau–Lifshitz equation describing solitons in a physically selected domain structure of a biaxial ferromagnet is presented. The structure and properties of new types of solitons that are strongly bound to the domain structure are investigated. Soliton behavior near the boundaries of their region of existence is considered. A comparative analysis of soliton

Flat cryogenic cells with a radiation source at one of the control (zero) electrodes create promising opportunities for studying the properties of charged accumulation layers in weakly conducting media. The question as to the origin of different relaxation times, short τ 0 or long τ ∞ ≫ τ 0, when the medium is exposed to a rectangular surge of the control voltage V g, remains relevant in this area

The paper reports the results of experimental studies of the thermal conductivity and density of CexSn1−xSe solid solutions in the temperature range 80–480 K. Under the assumption of elastic scattering of charge carriers, parabolic band and arbitrary degeneracy, the electronic and lattice components of thermal conductivity have been calculated. The characteristic features of the thermal conductivity

Whereas stable homogenous states of aqueous hydrocarbon solutions are typically observed at high temperatures and pressures far beyond the critical values corresponding to individual components, the stability of such system may be preserved upon transition into the region of metastable states at low temperatures and low pressures. This work is dedicated to the study of the thermal stability of a water-methane

The Mayer group expansion for solids proposed earlier is applied in prediction of the location of polymorphic phase transition line between the cubic and layered phases of polymeric nitrogen. The comparison with existing measurements revealed that theoretical calculations based on the proposed potential model calibrated on ab initio energy calculations are in agreement with existing experimental data

The thermal expansion at constant pressure of solid CD4 III is calculated for the low-temperature region where only the rotational tunneling modes are essential and the effect of phonons and librons can be neglected. It is found that in mK region there is a giant peak of the negative thermal expansion. The height of this peak is comparable or even exceeds the thermal expansion of solid N2, CO, O2,

Elastic-plastic transition at nanoindentation of (111) plane of pure C60 fullerite single crystals was studied. The onset of plastic deformation in the contact was noted due to the plateau formation in the initial part of loading curve. The estimated stress of plasticity beginning was found to be on the order of the theoretical shear stress required for homogeneous dislocation nucleation in the ideal

The transition between laminar and turbulent flows around a quartz tuning fork vibrating with frequency ω in superfluid 4He and concentrated solutions (5 and 15% 3He in 4He) in the temperature range 0.3–2.3 K has been studied. The temperature dependences of the amplitude of the critical transition velocity vcr are obtained. The relationship vcr ∼ √(ηω/ρ) is shown to be applicable for the description

The energy spectrum after reconnection of vortex loops at various temperatures of liquid (from a temperature close to absolute zero to T = 1.9 K) has been systematically studied. Initial conditions were varied at each temperature: the vortex loops were initially located in planes, the angle between which varied from 0 to π/2. A statistical approach was used to find the spectrum: the second-order longitudinal

The molecular dynamics method is used to study the melting of two-dimensional clusters that can form in electronic systems above the surface of superfluid helium with the help of triangular, square, hexagonal and round holding electrodes. Clusters with a fixed surface density of 108 cm−2, but different numbers of particles (from 3 to 406), are considered. It is shown that in defect-free clusters, the

The collective properties of surface electron systems consisting of several lines of charges are considered. To simulate the system, its characteristic frequencies of oscillations are found by applying Fourier analysis to the average coordinates of particles along and across the lines. The frequencies are compared with the theoretically obtained dispersion laws of plasma modes, calculated according

This article examines the penetration of a magnetic field into a high-temperature type-II superconductor that is in a viscous flow regime and in an external magnetic field. Analytical formulas are obtained for the depth and rate of the magnetic field penetration into the superconductor as a function of the problem parameters, particularly the exponent n that characterizes the rate of vortex penetration

For the first time, the temperature ρ(T) and magnetic field ρ(H) dependences of the electrical resistivity have been studied in compounds GdxPb1−xMo6S8 (x = 0.5, 0.7, 0.9), in the temperature range 2–300 K and magnetic fields up to 9 T. In the absence of a magnetic field, the compounds Gd0.9Pb0.1Mo6S8 and Gd0.7Pb0.3Mo6S8 exhibit features along ρ(T) (maximum and minimum for Gd0.9Pb0.1Mo6S8, and an inflection

The molecular phase theory approximation is used to calculate the phase diagrams of a hexagonal cylindrical magnetic superlattice nanotube, with alternating atomic layers consisting of two distinct materials. Cases in which these materials are both ferromagnetic and antiferromagnetic are considered. The transition temperature Tc for the system under investigation is calculated by the transfer-matrix

The authors have investigated the static critical behavior of a two-dimensional decorated Ising model on a square lattice in an external magnetic field, using computational physics methods. Particular consideration has been given to a special case when antiferromagnetic exchange interaction is observed only between decorated spins and spins located at lattice sites. It has been shown that at an external

A theoretical investigation of the combined resonance of interlayer conductivity and spin magnetization, in conductors with quasi-two-dimensional electronic energy spectra. Analytical expressions are obtained for the surface impedance, magnetic susceptibility, and the resonance interlayer conductivity component caused by Rashba–Dresselhaus spin-orbit interaction, with allowance for spatial dispersion

The sorption of hydrogen isotopes by a composite nanostructured carbon material containing palladium clusters with an average size of 3–5 nm was studied in the temperature range of 8–290 K. The total amount of sorbed hydrogen strongly depends on the method of manufacturing the composite and is 2–4.5% of the sample mass. In the kinetics of hydrogen sorption and desorption by a composite, two processes

The temperature behavior of Tl4HgI6 photoluminescence spectra is presented. The emission spectra are studied in the temperature range between 4.5 and 300 K and in the spectral range 350–650 nm. Two main emission bands at ∼551 nm and ∼448 nm are observed corresponding to the emissions of HgI2 and Tll impurity centers. It is assumed that the low-temperature emission band at ∼520 nm corresponds to the

The features of the plastic deformation of a micrograined magnesium alloy AZ31 under tension in the temperature range 4.2–295 K were studied. The samples were deformed in two structural states: the initial (after eight passes of equal channel angular pressing, 8ECAP) and annealed (after isothermal annealing at 573 K) states. In both cases, with decreasing temperature, an increase in the yield strength

Different types of high performance cryogenic helium units with dynamic-action machines are proposed. The creation of a helium refrigerator with an energy-generating cryogenic stage (ECS), in which helium is compressed at a temperature of 85.8 K in a cold centrifugal compressor, is also considered. The optimization of the refrigerator with an ECS is performed at the same cooling capacity of 576 W,

The molecular dynamics method is used to study the structure of two-dimensional clusters that can be created in electronic systems above the surface of superfluid helium, using triangular, square, hexagonal and round holding electrode geometries. Clusters with a fixed surface density of 108 cm−2, but different numbers of particles (from 3 to 406) are considered. The spatial configurations of particles

The dynamics of thermal radiation accompanying the condensation of tungsten nanoparticles in superfluid helium and vacuum was studied experimentally in the visible range. It was shown that during the first 100 μs the accompanying thermal energy of process in the case of superfluid helium is considerably higher than in vacuum at comparable temperatures after that it levels up. From a standpoint of the

The effect that the partial substitution of Cd for Y has on the mechanism of excess conductivity formation in polycrystalline Y1−хCdxBa2Cu3O7−δ with x = 0 (Y1), 0.1 (Y2), 0.3 (Y3), and 0.4 (Y4) is investigated. The resistivity ρ of the samples increases markedly with increasing x, and the critical temperature of the superconducting (SC) state transition, Tc, decreases. The mechanism responsible for

In the present paper, we have proposed the experimentally achievable method for the characterization of the collective states of qubits in a linear chain. We study a temporal dynamics of absorption of a single-photon pulse by three interacting qubits embedded in a one-dimensional open waveguide. Numerical simulations were performed for a Gaussian-shaped pulse with different frequency detunings and

Here we present calculations of the critical current of dc SQUID based on Josephson junction with un-conventional current-phase relation. We analyzed two cases of current-phase relation of junction: with anhar-monic and Majorana term. It is shown that the changing of the critical current in the case of the small geo-metrical inductance of dc SQUID based on Josephson junctions with unconventional current-phase

The main elastic moduli and piezoelectric modulus have been measured in holmium alumoborate single crystals. The renormalization of the permittivity, piezoresponse, and sound velocities, driven by the nematic-like paramagnetic phase in the sample, is considered. A significant variability of the results is detected, which is caused, presumably, by the fact that, under the action of external fields,

The φ0 junction demonstrates a rich variety of dynamical states determined by parameters of the Josephson junction and the intermediate ferromagnetic layer. Here we find several peculiarities in the maximal amplitude of magnetic moment m ^ y, taken at each value of the bias current, which we correlate to the features of the IV-characteristics of the φ0 junction. We show that a kink behavior in the

The electrical resistivity and thermal conductivity as functions of temperature, for an equiatomic Fe–Ni system are studied. The samples were obtained from nickel and iron powders by a 10 min electroconsolidation at a temperature of 1100 °C, pressure 35 MPa, and current ∼5 kA, and studied in the range of 4.2–300 K. It was found that the electrical and thermal conductivity of the electroconsolidated

The author has performed a theoretical analysis of the electronic structure of an elbow junction in single-walled “armchair” (4,4) and “zigzag” (7,0) carbon nanotubes consisting of 131 carbon atoms, as well as in pure carbon “armchair” (4,4) nanotubes consisting of 128 atoms, and “zigzag” nanotubes consisting of 126 atoms. It is shown that in the case of the elbow junction under study, a metal-semiconductor

Using X-ray diffraction analysis methods, the authors have studied the effect of stepwise isothermal annealing in the temperature range 150–670 C on the deformation microstructure parameters of cryodeformed VT1-0 titanium with micron, submicron, and nanoscale grain sizes. The structural states were obtained by rolling at liquid nitrogen temperature. This study discusses the influence of dislocations

The mechanical properties of a high-entropy CrMnFeCoNi2Cu alloy with an FCC lattice have been studied in a broad temperature range (4.2–350 K). The microhardness and Young’s modulus were measured at 300 K for two structural states. The temperature dependences of the yield strength, deforming stress, and strain rate sensitivity have been obtained. It was found that a high-strength state is realized

The topology of phase portraits for nonlinear oscillators driven by a periodic force undergoes significant changes within a narrow interval of the driving force frequencies v. This property leads to nonintegrability of the equations of motion, and stochastization of their solutions when v is periodically modulated. Such behavior is due to the violation of adiabaticity and destruction of the integral

A classification of the equilibrium states of single-sublattice magnets with spin s = 3/2 and SU(4) symmetry of the exchange interaction is developed. The study is based on the concept of quasi-averages and the principle of residual symmetry of degenerate equilibrium states. The transformation properties of the magnetic degrees of freedom are used to derive a system of equations for the order parameters

The theory of the giant conventional and inverse magnetocaloric effects (MCEs) is advanced on the basis of the theory of magnetism developed by A. I. Akhiezer, V. G. Bar’yakhtar, and S. V. Peletminsky in the classic monograph “Spin Waves”. The MCE in the shape memory alloy undergoing the first-order phase transition from the cubic ferromagnetic (FM) phase to the tetragonal antiferromagnetic (AFM) phase

Diffusion Magnetic Resonance Imaging (MRI) plays a very important role in studying biological tissue cellular structure and functioning both in health and disease. Proper interpretation of experimental data requires the development of theoretical models that connect the diffusion MRI signal to salient features of tissue microstructure at the cellular level. In this short review, we present some theoretical

It is well-known that a spin-transfer torque caused by a dc electric current can excite in a two-dimensional ferromagnetic film exchange-dominated magnetic solitons, often called “spin-wave bullets”, under the condition of a negative nonlinear shift of spin wave frequency. In this work, we demonstrate that in a quasi-one-dimensional (1D) case, e.g., in a nanowire spin-Hall oscillator, it is possible

A heterostructure composed of two parallel homogeneous layers is studied in the limit as their width and the distance between them shrinks to zero simultaneously. The problem is considered in one dimension and the squeezing potential in the Schrödinger equation is chosen in the form of a piecewise constant function. As a result, two families of point interactions with bound state energy are realized

We study numerically the integrable turbulence in the framework of the focusing one-dimensional nonlinear Schrodinger equation using a new method — the “growing of turbulence”. We add to the equation a weak controlled pumping term and start adiabatic evolution of turbulence from statistically homogeneous Gaussian noise. After reaching a certain level of average intensity, we switch off the pumping

A low-temperature feature is detected in nanogranular magnetic films with perpendicular anisotropy that have a low-field positive magnetoresistance: positive magnetoresistance is observed during the initial magnetization of the demagnetized sample, but is absent when the magnetic field is removed and/or during subsequent magnetizations. This effect is studied using a Cox(Al2On)1−x film with x = 0.60