


Vol 118, No 11-12 (12) (2023)
Articles
Effect of T-Invariance Violation in Scattering of Polarized 3He Nuclei on Tensor-Polarized Deuterons
Abstract
In the interaction of a transversely polarized nuclear beam with a tensor-polarized deuteron target, a nonzero value of the component of the total cross section corresponding to this combination of polarizations is an unambiguous signal of



Extended Analytical Model for the Description of Light Absorption Spectra of Linear Molecular Aggregates
Abstract
We study optical properties of linear dye aggregates in which the transition dipole matrix elements of two monomer molecules forming their unit cell are not coplanar with the aggregate axis, and the Frenkel exciton is delocalized along this axis. An analytical model has been developed for the description of polarization effects in the light absorption spectra of such aggregates. It is shown that the nature of their optical spectra differs drastically from previously studied linear aggregates with a single molecule per unit cell. The developed theory contains simple formulas of the well-known Davydov–McRae–Kasha model for conventional linear aggregates as a particular case. A quantitative explanation of the experimental data is given for the absorption spectra of the pseudoisocyanine bromide dye aggregate.



High-Frequency Shift and Extension of the Terahertz Radiation Spectrum up to 10 THz During Optical Rectification of High-Power Few-Cycle Near-Infrared Femtosecond Pump Radiation in a BNA Crystal
Abstract
The generation of terahertz radiation in a BNA crystal pumped by 1.24-µm femtosecond laser radiation from a Cr:forsterite laser system with a pulse duration of 100 and 35 fs and a pump density of 10 mJ/cm2 has been realized. The achieved generation efficiency is 0.1%. It is found that a decrease in the pump pulse duration from 100 to 35 fs leads to the generation of high-frequency components in the ranges of 2.5–6.5 THz and 9‒10.5 THz in the generated radiation spectrum. Simulation of the terahertz radiation generation based on the solution of Maxwell’s equations by the finite-difference time-domain method has made it possible to adequately describe the measured spectra. The generation of broadband high-frequency terahertz radiation in the BNA crystal pumped by the Cr:forsterite laser system allows one to consider this schematic as an alternative to sources based on the BNA crystal pumped by a Ti:sapphire laser system.



On the Separation of a Monolayer of Charged Microparticles in a Parabolic Confinement
Abstract
The evolution of an initially planar monolayer of charged microparticles in a complex plasma (plasma crystal) in horizontal (in the plane of the monolayer) and vertical parabolic confinements has been considered. The separation (buckling instability) of a Yukawa system into several layers at the weakening of the vertical confinement, as well as structural changes in such a plasma crystal, has been studied using the molecular dynamics method. In particular, it has been shown that the radial inhomogeneity of the plasma crystal qualitatively changes the character of the separation compared to homogeneous systems. Indeed, the separation begins in the center of the crystal, where the average distance between particles is minimal, and propagates in the form of a wave towards the periphery of the system at the weakening of the vertical confinement. This explains features of the behavior of plasma crystals in recent experiments with the complex plasma.



Radiative Losses of Deuterons, Tritons, and Alpha Particles on Tungsten Ions in the Plasma of the ITER and EU-DEMO Tokamaks
Abstract
Integral radiative losses of deuterons, tritons, and alpha particles on impurity tungsten ions have been calculated for the first time within the statistical theory of the atom for the designed operational regimes of the ITER and EU-DEMO tokamak reactors. It was previously shown within the statistical theory of the atom that specific radiative losses of this new ion channel are comparable with specific electron radiative losses, which also include losses due to bremsstrahlung, radiative and dielectron recombination. Integral radiative losses have been calculated within the numerical model of fusion power isolines, which was previously proposed to study the operational space and design regimes of tokamak reactors. Spatial distributions of the tungsten density with various degrees of peaking in the center of a plasma column have been considered to study the influence of the accumulation of the impurity on integral radiative losses. It has been found that the studied new channel adds about 20 and 30% to the total integral radiative losses on tungsten in the ITER and E-U‑DEMO tokamak reactors, respectively. Consequently, this channel of radiative losses should be taken into account to examine in more detail the working scenarios of these devices.



Binary Coding by Microwave Pulses on the Transverse Magnetization of the Tetracyanoethylene Radical
Abstract
The possibility of coding the response of the electron–nuclear system of the tetracyanoethylene radical under microwave pulse irradiation in combination with a pulsed magnetic field gradient in the nanosecond timescale by a binary code is demonstrated. To this end, the tetracyanoethylene radical, which has a well-resolved equidistant electron paramagnetic resonance spectrum due to the interaction of the electron with equivalent magnetic nuclei, is used. The aim is to demonstrate the possibility of implementing this procedure physically rather than to encode the longest possible sequence.



Nodal line topological superconducting state in quasi-one-dimensional A2Cr3As3 (A=K,Rb,Cs) superconductors



Bound States of a Short-Range Defect on the Surface of an Intrinsic Antiferromagnetic Topological Insulator in a Noncollinear Phase
Abstract
The features of electronic states on the surface of an intrinsic antiferromagnetic topological insulator (AFM TI) containing defects are theoretically investigated. Our approach takes into account the role of the electrostatic potential and the variation in the orientation of magnetic moments in the near-surface layers. A change in the spectral characteristics of the surface states under the transformation of magnetization from an equilibrium AFM phase of A-type to a ferromagnetic phase through a noncollinear texture is described. It is shown that in AFM TI with uniaxial anisotropy, an external magnetic field applied along the easy axis can cause a significant modulation of the exchange gap size in the spectrum of surface states and even invert the gap sign. Modeling the single defect effect as a surface potential perturbation over a finite scale, we analytically investigate the formation of a bound state and its behavior depending on the strength of potential and exchange scattering by the defect and the exchange gap size. The energy level of the bound state is demonstrated to experience a sharp shift in the vicinity of the spin-flop transition. The theoretical results obtained allow us to provide a consistent explanation of recent experimental data on scanning tunneling spectroscopy of antisite defects on the surface of the prototype AFM TI MnBi2Te4 in an external magnetic field.



Reentrant proximity-induced superconductivity for GeTe semimetal



Anisotropy of the Critical Current and Abrikosov Vortex Pinning in Magnetic Superconductor EuCsFe4As4
Abstract
In this study, for the first time, we present a systematic study of the critical current density Jc at two magnetic field orientations



On the Fundamental Difference between the Effects of Electrical and Mechanical Vibrations on the Dynamics of a Charge Density Wave
Abstract
The effects of radio-frequency electric and strain fields on the depinning and sliding of a charge density wave in the quasi-one-dimensional conductor TaS3 have been compared. The amplitude dependence of the threshold voltage Vt (zeroth Shapiro step) has been studied for both fields. The threshold voltage Vt decreases with increasing radio-frequency electric field Erf at increasing rate |dVt/dErf|, whereas with increasing strain field, the decrease in the threshold voltage Vt is saturated, approaching a constant value. This result indicates a qualitative difference between the mechanisms of influence of the electric and strain fields on the dynamics of the charge density wave and is explained by the modulation of the sliding velocity of the charge density wave and pinning potential in the former and latter cases, respectively. In practice, the result allows one to distinguish the mechanical impact on the dynamics of the charge density wave from the influence of electrical interference at the same frequency.



Simultaneous Observation of the Cyclotron Resonances of Electrons and Holes in a HgTe/CdHgTe Double Quantum Well under “Optical Gate” Effect
Abstract
Spectral studies of the photoconductivity in the temperature range of T = 5–70 K, as well as studies of the magneto-absorption and magnetotransport at T = 4.2 K, have been performed in a HgTe/CdHgTe heterostructure with a double quantum well under an “optical gate” effect. Studies of magneto-absorption spectra under the controlled optical exposure have made it possible to observe absorption lines caused by both the cyclotron resonances of electrons and holes simultaneously. The coexistence of electrons and holes in the HgTe/CdHgTe double quantum well with a relatively large bandgap (~80 meV) indicates the appearance of a strongly inhomogeneous light-induced distribution of charge carriers in the plane of the structure. Experimental results obtained clearly demonstrate disadvantages of the control of the Fermi level positions in heterostructures with HgTe/CdHgTe quantum wells by means of the optical gate.



Efficient Acceleration of Electrons by Moderate-Power Femtosecond Laser Pulses
Abstract
The relativistic self-trapping of a laser pulse is an efficient mechanism for the acceleration of electrons, which
allows one to achieve an extreme charge of a high-energy particle beam and the corresponding conversion
coefficient of laser energy. It has been shown that the compression of the femtosecond laser pulse in this
regime using the innovative compression after compressor approach (CafCA) [E.A. Khazanov,
S.Yu. Mironov, and G. Mourou, Phys. Usp. 62, 1096 (2019)] to extremely short durations keeping the energy
of the laser beam significantly increases the efficiency of particle acceleration. This effect has been illustrated
on the example of the Multitera laser facility for the project implemented at the Russian National Center for
Physics and Mathematics.



Interlayer Conductivity of Quasi-Two-Dimensional Layered Conductors in a Magnetic Field at Yamaji Angles
Abstract
The behavior of the interlayer magnetoresistance Rzz is analyzed in quasi-two-dimensional layered metals in
a magnetic field tilted at Yamaji angles at which the minimum of the interlayer conductivity is observed. The
cases of the Lorentzian line shape of Landau levels and of the shape corresponding to the self-consistent Born
approximation are studied. At high fields, the behavior Rzz B3/2 is theoretically predicted, which agrees well
with experimental data.



Interplay Between Electron Correlations, Magnetic State, and Structural Confinement in LaNiO3 Ultrathin Films
Abstract
We report a theoretical study of the effects of electron correlations and structural confinement on the electronic properties and magnetic state of LaNiO3 (LNO) thin films epitaxially deposited on the



Simulation of the Wave Turbulence of a Liquid Surface Using the Dynamic Conformal Transformation Method
Abstract
The dynamic conformal transformation method has been generalized for the first time to numerically simulate the capillary wave turbulence of a liquid surface in the plane symmetric anisotropic geometry. The model is strongly nonlinear and involves effects of surface tension, as well as energy dissipation and pumping. Simulation results have shown that the system of nonlinear capillary waves can pass to the quasistationary chaotic motion regime (wave turbulence). The calculated exponents of spectra do not coincide with those for the classical Zakharov–Filonenko spectrum for isotropic capillary turbulence but are in good agreement with the estimate obtained under the assumption of the dominant effect of five-wave resonant interactions.



Magnetoresistance of a HgTe/CdHgTe Double Quantum Well in an In-Plane Magnetic Field
Abstract
A magnetic field parallel to the layers of a double quantum well with conventional semiconductor constituents
leads to a relative shift of the conduction band spectra of the constituent layers along the wave vector perpendicular
to the field. If the states of the layers are tunnel-coupled, a tunneling gap is formed at the intersection
of the single-layer spectra and is shifted upward with increasing field. This leads to striking features in the
magnetoresistance caused by intersections of the Fermi level with the edges of the tunneling gap. Similar
studies of transformations of the spectrum of the double quantum well in a HgTe/CdHgTe heterosystem,
which has a p-type conductivity and HgTe layers with a gapless inverse energy spectrum, are reported in this
work. Our experiments and corresponding calculations in the eight-band kp approach indicate that the evolution
of the magnetoresistance with the variation of the in-plane field here has a much more complex and
diverse character depending qualitatively on the thickness of the layers.



Transport Properties of the Magnetic Topological Insulators Family (MnBi2Te4)(Bi2Te3)m (m = 0, 1, …, 6)
Abstract
Systematic studies of magneto-transport properties of the whole (MnBi2Te4)(Bi2Te3)m family of magnetic topological insulators (



Magnon Topological Transition in Skyrmion Crystal
Abstract
We study the magnon spectrum in skyrmion crystal formed in thin ferromagnetic films with Dzyaloshinskii–Moriya interaction in presence of magnetic field. Focusing on two low-lying observable magnon modes and employing stereographic projection method, we develop a theory demonstrating a topological transition in the spectrum. Upon the increase in magnetic field, the gap between two magnon bands closes, with the ensuing change in the topological character of both bands. This phenomenon of gap closing, if confirmed in magnetic resonance experiments, may deserve further investigation by thermal Hall conductivity experiments.



On the Character of Superconductivity and Topological Properties of SnAs
Abstract
The paper describes results of the band structure measurements of SnAs single crystals by the ARPES technique. We performed detailed analysis of isoenergetic surfaces in the vicinity and below the Fermi energy. The ARPES experimental data are consistent with theoretically predicted shape of the SnAs Fermi surface. The determined type of the Fermi surface provides the basis for estimating the Ginzburg–Landau parameter, from which it follows that SnAs is a type-I superconductor. In addition, our results of ARPES measurements confirm the presence of band splitting in the energy spectrum at the



Local Quench within the Keldysh Technique
Abstract
The problem of quantum scalar field evolution after an instantaneous local perturbation (quench) is considered. A new approach to descriptions of a quench from an arbitrary initial state is developed in the framework of the Keldysh technique. This approach does not require the procedure of the analytical continuation, which can be ambiguous in some cases. The evolution of the energy density after local quench is calculated for a simple case, and its dependence on the interaction region width and the initial conditions is analyzed.



On-Demand Reconstruction of the Waveform of a Mössbauer Gamma-Ray Photon by Means of Delayed Acoustically Induced Transparency
Abstract
A method has been proposed to reconstruct at arbitrary time the spectral–temporal characteristics of a
14.4-keV single-photon wave packet that is emitted by a 57Co source and is resonantly absorbed in the
medium of 57Fe nuclei. The method is based on the frequency separation of the field emitted by the source
and resonance nuclear polarization induced by this field by means of delayed acoustically induced transparency
of the absorber, which appears after the activation of oscillations of the absorber at the corresponding
frequency and amplitude. The proposed method has been compared to the known quantum-optical memory
methods and methods of nuclear polarization control in the gamma range. Experimental conditions have
been proposed to implement the method. It has been shown that this method allows the implementation of
the time-resolved Mössbauer spectroscopy of various media.



Tensor train optimization of parameterized quantum circuits



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