


Vol 118, No 7-8 (10) (2023)
Articles
Possible Search for Majorana Neutrinos at Future Lepton Colliders
Abstract
We discuss the process



Atomic Electron Shell Excitations in Double-β Decay
Abstract
The problem of the transition of electron shells of atoms to excited states in the process of neutrinoless double-



Bjorken sum rule with analytic coupling at low Q2 values



Influence of the Carrier–Envelope Phase on the Generation of the Multioctave Supercontinuum and Ultrashort Pulses in Antiresonant Hollow Waveguides
Abstract
The influence of the carrier–envelope phase on the spectrum of the supercontinuum and on the characteristics of ultrashort pulses, which are formed by the nonlinear optical transformation of pump pulses in an argon-filled antiresonant hollow waveguide has been demonstrated. The experimental and theoretical analysis has shown that the soliton self-compression of pump radiation with a central wavelength of about 2 μm forms a pulse with a duration of nearly one optical cycle and with a spectrum broadened to the region of 400‒800 nm, where interference with the broadband third harmonic generated by the same pulse is observed. The interference pattern is sensitive to the carrier–envelope phase of the laser pulse. The analysis of the interference pattern provides information on the difference of the spectral phases of the soliton and third harmonic in the spectral range wider than an octave and allows one to control the duration of pulses formed in the process of soliton self-compression.



Controlling the Angular Divergence of Terahertz Radiation Generated by Single-Color Filaments Using Phase Optical Elements
Abstract
We have experimentally obtained two-dimensional distributions of terahertz radiation generated by one or four filaments formed by phase optical elements in air. It has been demonstrated that the use of the phase mask reduces the propagation angles of terahertz beam by approximately one and a half times, which is due to the interference of terahertz radiation from four sources. The use of the Dammann grating slightly enlarges these angles.



Giant Planar Hall Effect in an Ultra-Pure Mercury Selenide Single Crystal Sample
Abstract
A giant planar Hall effect with an amplitude of about 50 mΩ cm at a temperature of T = 80 K in a magnetic field of 10 T has been detected in an ultra-pure HgSe single crystal sample with an electron density of 5.5 × 1015 cm–3. Its oscillating dependence on the rotation angle of the sample in various magnetic fields has been determined. Attributes (oscillation period, positions of extrema, correlation between the amplitudes of planar Hall and planar longitudinal magnetoresistance) indicate that the planar Hall effect in this nonmagnetic gapless semimetal with an isotropic Fermi surface originates from the chiral anomaly. This is a solid argument for the topological nature of the electronic spectrum of HgSe.



Convolutional Neural Networks for Predicting Morphological and Nonlinear Optical Properties of Thin Films of Quasi-Two-Dimensional Materials
Abstract
Two-dimensional materials are promising candidates for the creation of flat photonics devices. The main problem of using such materials for applied applications is the complexity of creating films of specified geometric parameters. The films of two-dimensional materials made by exfoliation or chemical deposition methods are usually randomly distributed over a large area and have a large thickness spread. In this paper, we use convolutional neural networks to predict the film thickness of a quasi-two-dimensional material based on optical microscopy data. Hexagonal boron nitride, which is actively used in the creation of flat electronic and optoelectronic devices, was chosen as a test material. Due to the high spatial resolution of microscopy, it is possible to achieve high accuracy in predicting the thicknesses of flat areas of the sample, which allows for rapid characterization of structures. In addition, using the example of the signal of the third optical harmonic, we show the possibility of predicting the magnitude of the nonlinear optical response of the film, which expands the scope of the method.



Features of the Scaling of the Anomalous Hall Effect in (CoFeB)x(LiNbO3)100 − x Nanocomposite Films Below the Percolation Threshold: Manifestation of the Cotunneling Hall Conductance?
Abstract
A scaling behavior of the anomalous Hall effect resistivity ρAHE versus the longitudinal resistivity ρ in (CoFeB)x(LiNbO3)100 − x nanocomposites with a low content of dispersed Co and Fe atoms (Nd ~ 4 × 1020 cm−3) in an amorphous LiNbO3 matrix is studied in the range x ≈ 40–48 at % below the percolation threshold xp ≈ 49 at %. A logarithmic temperature dependence of the conductivity σ ~ lnT has been observed in the range x ≈ 44–48 at %, which is transformed in the range x ≈ 40–42 at % to a square root law lnσ ∝ ‒(T0/T)1/2, which is characteristic of cotunneling transport processes in nanocomposites. It has been found that the exponent n ≈ 0.24 in the scaling law ρAHE/x ∝ [ρ(x)]n coincides within an accuracy of 5% with the exponent n in a similar dependence for nanocomposites based on the (CoFeB)x(Al2O3)100 − x matrix with a high content Nd ~1021–1022 cm–3 and with the exponent n in a parametric dependence ρAHE ∝ [ρ(T)]n for the samples with the minimum content x ≈ 40 at %. The found features are attributed to the correlated change in the probability of cotunneling transitions in a set of more than three centers under the effect of spin–orbit coupling. The manifestation of the barrier tunneling anomalous Hall effect at granule interfaces is also p-ossible.



Comparison of the Gap Structure of Underdoped and Overdoped Superconducting Pnictides BaFe2 – xNixAs2
Abstract
We compare the structure of the superconducting order parameter of overdoped BaFe1.88Ni0.12As2 and underdoped BaFe1.92Ni0.08As2 pnictides with similar



Magnetic Helix in a Multilayer Ferromagnetic Nanoparticle and Its Rotation Induced by an Electric Current
Abstract
The dynamics of the magnetization induced by an electric current flowing in a multilayer nanoparticle is studied theoretically. A region of the parameters where the coherent rotation of a magnetic helix, which is formed in this system due to the magnetostatic interaction of ferromagnetic layers, has been determined analytically. Estimates indicate that the predicted nonlinear oscillation mode of the magnetization can be observed experimentally.



Diffusive Modes of Two-Band Fermions Under Number-Conserving Dissipative Dynamics
Abstract
Driven-dissipative protocols are proposed to control and create nontrivial quantum many-body correlated states. Protocols conserving the number of particles stand apart. As well-known, in quantum systems with the unitary dynamics the particle number conservation and random scattering yield diffusive behavior of two-particle excitations (diffusons and cooperons). Existence of diffusive modes in the particle-number-conserving dissipative dynamics is not well studied yet. We explicitly demonstrate the existence of diffusons in a paradigmatic model of a two-band system, with dissipative dynamics aiming to empty one fermion band and to populate the other one. The studied model is generalization of the model introduced in F. Tonielli, J.C. Budich, A. Altland, and S. Diehl, Phys. Rev. Lett. 124, 240404 (2020). We find how the diffusion coefficient depends on details of a model and the rate of dissipation. We discuss how the existence of diffusive modes complicates engineering of macroscopic many-body correlated states.



Gravity through the prism of condensed matter physics



Experiment on Highly Efficient Deflection of a 1-GeV Proton Beam by a Bent Crystal at the PNPI Synchrocyclotron
Abstract
The deflection of a 1-GeV proton beam by a bent silicon crystal 1 mm long by an angle of (3.0 ± 0.1) mrad with an efficiency of (32 ± 3)% for end-face capture into the channeling regime has been observed for the first time in the presented experiment. The developed crystal deflector makes it possible to increase the beam deflection angle and can be used to produce low-intensity beams at intermediate energies.



Measurement of the Energy of the 8.3-eV 229Th Isomer Using the Photoelectric Effect
Abstract
It is proposed to use the photoelectric effect on inner s shells of the 229Th atom to more accurately determine the energy of its 8.3-eV isomer. The calculation has been performed using the Feinberg–Migdal shaking theory, which gives the probability of the formation of the isomer up to



GRB 221009A, Its Precursor, and Two Afterglows in the Fermi Data
Abstract
We study GRB 221009A, the brightest gamma-ray burst in the history of observations, using Fermi data. To calibrate them for large inclination angles, we use the Vela X gamma-ray source. Light curves in different spectral ranges demonstrate a 300 s overlap of afterglow and delayed episodes of soft prompt emission. We demonstrate that a relatively weak burst precursor that occurs 3 min before the main episode has its own afterglow, i.e., presumably, its own external shock. This is the first observation of such phenomenon which rules out some theoretical models of GRB precursors. The main afterglow is the brightest one, includes a photon with an energy of 400 GeV 9 h after the burst, we show that it is visible in the LAT data for up to two days.



Evolution of the Luminescence Properties of Single CsPbBr3 Perovskite Nanocrystals During Photodegradation
Abstract
The evolution of the luminescence blinking of single CsPbBr3 perovskite nanocrystals with a characteristic size of ~25 nm during photodegradation has been experimentally investigated. It has been demonstrated that the blue shift of the luminescence peak and a decrease in the average luminescence intensity are accompanied by the increasing role of nonradiative Auger processes underlying the charging mechanism of blinking. A method based on the analysis of photon antibunching g2(0) and exciton and biexciton recombination rates is used to determine the blinking mechanism. The data obtained have made it possible to reveal a transition from the trapping to charging blinking mechanism with a change in the sizes of a CsPbBr3 single nanocrystal.



Experimental Study of the Compressibility of a Helium Plasma at a Pressure up to 20 TPa
Abstract
A nonideal helium plasma has been compressed to a density of ρ ≈ 14 g/cm3 at a pressure of



Spatially Inhomogeneous Ultrafast Demagnetization of a Nickel Magnetoplasmonic Crystal
Abstract
A 50% decrease in the magneto-optical Kerr effect is observed in the experiment on subpicosecond laser-induced demagnetization of the one-dimensional all-nickel magnetoplasmonic crystal. The femtosecond pulse energy density is comparable to that required to achieve similar values in thin films. Numerical calculations show that such a decrease is not governed by the uniform reduction of surface magnetization, but is the result of the appearance of demagnetized and non-demagnetized areas of the surface.



Influence of the Gd Concentration on Superconducting Properties in Second-Generation High-Temperature Superconducting Wires
Abstract
Systematic studies of second-generation high-temperature superconducting wires with Gd excess relative to the stoichiometric GdBa2Cu3O7 composition are reported. It has been revealed that filamentary defects in the form of non-superconducting Gd2CuO4 phase located along the ab plane are formed during film growth. These inclusions lead to a change in the pinning mechanism of the vortex structure, due to which the peak of the critical current at +15% Gd is clearly observed.



Generation of Quantum Vortices by Waves on the Surface of Superfluid Helium
Abstract
The formation of quantum vortices by two mutually perpendicular waves excited on the surface of superfluid helium has been observed. The interaction of negative charges injected under the surface of He-II with the vortex flow of the liquid, which is formed by surface waves at frequencies from 20 to 49.9 Hz, in the temperature range of 1.5–2.17 K has been studied experimentally by analyzing the current distribution detected by vertically oriented segments of a receiving collector. The efficient capture of injected charges by quantum vortices has been observed at a temperature of T = 1.5 K, which leads to a significant redistribution of currents between segments of the receiving collector. Charges leave traps on quantum vortices at temperatures near T = 1.7 K. With a further increase in the temperature, injected charges are scattered on vortex flows of the normal component, which are generated by surface waves.



Thermally Induced Magnetization Reversal in Submicron Ni Particles Formed on Single Crystalline Lithium Triborate
Abstract
The influence of the thermally induced magnetoelastic effect on the magnetization reversal field in 0.9 × 0.3 × 0.03-μm Ni particles formed on a single crystalline lithium triborate (LiB3O5) substrate has been studied. It has been shown experimentally that this substrate can reduce the magnetization reversal field of particles by a factor of more than 1.5 as the temperature of the sample increases from 30 to 45°C. This reduction of the reversal field is due to magnetoelastic anisotropy induced in the particles by the difference between the thermal expansion coefficients of the substrate along different crystallographic axes.



Molecular Dynamics Study of the Structural and Diffusion Properties of Dehydrated Layered Double Aluminum and Lithium Hydroxide
Abstract
An atomistic model of dehydrated Cl-doped double layer aluminum–lithium hydroxide



Acoustic Coupling between Magnon Bose−Einstein Condensates in Yttrium Iron Garnet Films
Abstract
The excitation of a magnon Bose−Einstein condensate in an yttrium iron garnet film due to acoustic coupling with the condensate in the second sample is experimentally studied. A nonlinear nature of this excitation is demonstrated. The formation of a phonon Bose−Einstein condensate in the substrate is assumed. This experiment opens the possibility of creating qubits based on acoustically interacting Bose−Einstein condensates.



Comment on “On the Electric Area of an Electromagnetic Pulse”(Pis'ma v ZhETF 118(4), 291 (2023))


