bluuebunny/crossref_metadata_2025 huggingface dataset:
Visual study of domain structure in RbNi1−xCoxF3 hexagonal ferrimagnets
Authors: Belyaeva A. I. , Petrov S. V. , Stel’makhov Yu. N. , Yur’ev V. P.
Published: December 2024

We report a visual study of the domain structure of thin crystal platelets of the hexagonal ferrimagnetic system RbNi1−xCoxF3 (x = 0.19 and x = 0.23), which has an “easy axis” type of anisotropy, in the temperature range 4.2−140 K in an external magnetic field H║C6. It is shown that depending on the growth conditions different types of open domain structures may arise and exist stably, with the surface domains of opposite magnetization typical of thick (h > hc) magnetically uniaxial platelets. The parameters of the structures studied are in accord with the results of calculations based on known theoretical models.
Possibility of quantum tunneling of vortices in thin superconducting films
Authors: Glazman L. I. , Fogel’ N. Ya.
Published: December 2024

Estimates showing the possibility of observing penetration of vortices into a thin superconducting film as a result of quantum fluctuations of the order parameter are presented.
Diamagnetic oscillations of thermodynamic and kinetic characteristics of a metal at ultralow temperatures
Authors: Gurzhi R. N. , Kopeliovich A. I.
Published: December 2024

It is shown that when the dependence of the chemical potential of electrons on the magnetic field intensity is taken into account, the structure of quantum singularities of the electronic density of states changes, leading to a considerable restructuring of oscillatory phenomena in metals at ultralow temperatures.
Mechanism of damping of axial-torsional oscillations of type-ll superconductors in a magnetic field in the presence of pinning
Authors: Shukhman V. A.
Published: December 2024

An attempt is made to explain the experimentally observed maximum in the dependence of the damping of axially-torsional oscillations of type-II superconductors in a magnetic field on the concentration of pinned vortices. The fact that the vortices detached from the pinning centers (“free” vortices), due to their interaction with pinned vortices moving relative to them together with the specimen, are deflected by large angles relative to the direction of the external magnetic field, i.e., they obtain additional energy from the oscillating system, is taken into account. This energy is dissipated by them as they return to the equilibrium position—along the direction of the external magnetic field. With the help of a simple model, the magnitude of the losses is calculated, the existence of a maximum of these losses is demonstrated, and the conditions for the appearance of the maximum are analyzed.
Penetration of magnetic field H < H
c10 into Pb–In single crystals containing freshly introduced dislocations
Authors: Beloshapka V. Ya. , Platkov V. Ya.
Published: December 2024

With a view to obtaining information about the superconducting properties of inhomogeneous materials we investigated the effect of a magnetic field H on internal friction in Pb–In single crystals containing freshly introduced dislocations as well as dislocations blocked by atoms of an alloying element. It was found that when fresh as well as blocked dislocations are introduced into a crystal a magnetic field H < Hc10 affects the amplitude-dependent internal friction, starting from fields H*≃0.2 Hc10. In crystals containing freshly introduced dislocations the field dependence of the damping constant and the modulus defect, measured at a fixed amplitude ε0, is represented by curves with minima near Hc10. In contrast, in crystals with blocked dislocations the dependence of the damping constant and the modulus defect on H are represented by curves with maxima near Hc10. Magnetic flux was observed to be trapped after the application of fields H <Hc10. The results suggest a local penetration of the field into an inhomogeneous superconductor when H ≪Hc10. The locally penetrating magnetic field H effectively changes the dislocation dynamics. The strong coupling of a vortex with a dislocation in fields H <Hc10 is due to a change in the critical superconducting parameters near dislocations.
Application of the Josephson effect to the detection of gravitational and inertial forces
Authors: Verozub L. V.
Published: December 2024

It is shown that the Josephson effect can be used to detect gravitational and inertial forces.
Critical magnetic fields in the superconducting system PdHx (Dx)
Authors: Ginodman V. B. , Zherikhina L. N.
Published: December 2024

The critical magnetic fields for the system PdHx (Dx) have been measured over the interval of superconducting hydrogen (deuterium) concentrations x = 0.77–1.00 at temperatures 0.35–11 K. The transition to the superconducting state was detected simultaneously by the change in resistivity and in the differential magnetic susceptibility. It was shown that PdHx is a type II superconductor for x < 1, but becomes a type I superconductor for x = 1. The coefficient of the electronic specific heat γ was calculated from the measured Hc2(T) dependence according to the formula γ=2.2⋅10−5ρ−1dHc2/dTTc. The critical magnetic field corresponding to the superconducting transition determined by the resistance method was associated with the existence of surface superconductivity.
Pinning in superconductors containing regions with precipitation of a new phase
Authors: Golub A. A. , Grimal’skiĭ O. V. , Postolatiĭ V. M.
Published: December 2024

The elementary pinning force in superconductors containing a region of precipitation of a new phase is calculated on the basis of the solution of linear integral equations for the order parameter. The limits of clean and dirty superconductors are examined. Results are obtained for different parameters of the normal inclusion and of the superconducting matrix. The dependence of the elementary pinning force on the thickness of the normal interlayer is determined.
Kinetics of a paramagnetic impurity in an electronic thermostat
Authors: Ivashin A. P. , Tsukanov V. D.
Published: December 2024

The kinetics of paramagnetic impurity interacting with an equilibrium electron gas is investigated. Systems of equations are derived and the kinetic coefficients are calculated for parameters describing the state of an impurity of arbitrary spin.
Causes of the formation of two-site self-trapped excitations
Authors: Khizhnyakov V. V. , Sherman A. V.
Published: December 2024

The adiabatic surface of self-trapped p-type excitons interacting with e-vibrations in a cubic crystal is considered in the paper. It is shown that for comparable exciton band-widths and Stokes losses and for considerable anisotropy of the exciton band, the energetically lowest self-trapped state is a state in which the excitation is distributed between two neighboring sites. This, as well as the nature of the lattice deformation, is consistent with experimental observations made on alkali-halide crystals and crystals of inert gases. We demonstrate that two-site and one-site self-trapped excitons can exist; this makes it possible to interpret some features in the optical spectra of crystals of these classes.
Superplasticity of solid parahydrogen
Authors: Alekseeva L. A. , Krupskiĩ I. N.
Published: December 2024

The plastic properties of single-crystal specimens of parahydrogen have been studied at helium temperatures. It was found that the plasticity increases sharply as the temperature is reduced to 1.8-2 K. The phenomenon of flow of sufficiently perfect p-H2 crystals under the force of gravity was observed. The role of vacancy mechanisms in processes of plastic deformation is discussed.
Oscillations in a Josephson junction of superconducting films
Authors: Batyev É. G. , Borisyuk V. A.
Published: December 2024

A Josephson junction consisting of very thin superconducting films is examined. It is shown that the Josephson plasma frequency can be substantially renormalized (compared to the frequency of the massive structure), and in the limit of a very thin structure its magnitude does not depend on the electrical characteristics, i.e., on the electron charge and dielectric constant (similar oscillations are apparently possible in a junction consisting of thin layers of neutral superfluid liquid He3 and He4). Oscillations with finite wavelength are also examined.
Pinning of flux lines on grain boundaries in superconducting niobium films
Authors: Prokhorov V. G. , Kaminskiĭ G. G.
Published: December 2024

The magnetic field dependence of the volume pinning force in niobium films with Fe, Ge, and V impurities is investigated. It is shown that the main pinning centers in the films are grain boundaries, and their interaction with vortex lines is a result of electron scattering.
Mixed state of a superconductor with filamentary inhomogeneities
Authors: Shapiro B. Ya.
Published: December 2024

A theory of the mixed state arising in metals consisting of filaments of a higher-temperature superconductor in a metallic matrix is constructed. It is shown that depending on the orientation of the magnetic field relative to the axis of the filament, as well as on the temperature, the superconducting states that appear have the form of filaments or plates, extending along the magnetic field. The magnetic moment and the temperature dependences of the characteristic dimensions of such states, as well as the magnetic properties of the medium consisting of a large number of metallic filaments are determined.
Experimental observation of superradiance in pyrene-doped diphenyl crystals
Authors: Zinov’ev P. V. , Lopina S. V. , Naboikin Yu. V. , Silaeva N. B.
Published: December 2024

We have studied the superradiance of pyrene-doped diphenyl molecular crystals over the temperature range 1.5−40 K. The experimental results1) are presented along with several proposed mechanisms for the creation of coherence among the pyrene impurity molecules.
Analogy between the magnetic field of a pulsar and the field of a magnetized superconducting sphere
Authors: Mkrtchyan G. S. , Sedrakyan D. M.
Published: December 2024

We calculate the field induced by a superconducting sphere homogeneously magnetized throughout its volume. It is proposed that a similar field is generated in a neutron star on account of entrainment of superfluid protons by neutrons.
Excess thermodynamic functions of liquid He3–He4 solutions
Authors: Karnatsevich L. V. , Bogoyavlenskiĭ I. V. , Konareva V. G.
Published: December 2024

Different experimental data are studied analytically in order to obtain the main excess thermodynamic functions of liquid He3–He4 solutions. Data in the literature for solutions under the saturated vapor pressure and data obtained for solutions under high pressures, up to solidification, are used. The dependence of the excess thermodynamic functions (GE, SE, HE) on the pressure, temperature, and concentration of the mixture are analyzed in detail. These data are compared to the results of calculations based on different theoretical models. Conclusions are drawn concerning the relative role of different quantum mechanisms leading to nonideality of He3–He4 liquid isotopic mixtures.
Some static and dynamic properties of magnetic domain walls in ferromagnetic ferroelectrics
Authors: Soboleva T. K. , Stefanovskii E. P.
Published: December 2024

We have investigated some static and dynamic characteristics (such as effective thickness, density of surface energy, and velocity of domain walls) of magnetic domain walls in rhombic, weakly anisotropic ferromagnetic ferroelectrics. These parameters have been found as a function of the electric polarization of the external electric field.
The anomaly of the thermal expansion of solid N2 with O2 impurities. Inclusion of spin-librational interaction
Authors: Freĭman Yu. A. , Ezhovski A.
Published: December 2024

It is shown that in the low-temperature anomaly of the thermal expansion of the solid solution N2–O2, aside from the contribution of exchange-coupled pairs of oxygen molecules which is quadratic in the concentration, there is a contribution which is linear with respect to the concentration of single impurity molecules. This contribution arises due to the fact that the effective spin-axis coupling, which determines the splitting of the ground triplet state of the O2 molecule, is renormalized by the spin-libration interaction. The contributions of both mechanisms become equal at O2 concentrations c ∼ 1%.
Features of the critical current in wide superconducting films in a weak magnetic field at temperatures far from the critical temperature
Authors: Ichkitidze L. P. , Skobelkin V. I. , Shermergor T. D.
Published: December 2024

The dependence of the critical current Ic on a perpendicular magnetic field H has been studied in the range − 300 Oe ≤ H ≤ + 300 Oe in polycrystalline and single-crystal niobium and niobium nitride films of thickness ∼ 100 μ and width w ≈ 50–300 μ. In some niobium films it was observed that the Ic (H) curves did not agree on varying H in the direct and reverse directions. The hysteresis decreased or completely disappeared on increasing w or T and on bombarding the specimens with argon ions. The experimental results are explained on the basis of a model of an edge barrier in the films, where the values of the barriers are different for different edges as a result of the action of weak bulk pinning.
Surface tension of liquid neon
Authors: Baidakov V. G.
Published: December 2024

The capillary constant of liquid neon has been measured and the surface tension has been determined over a wide range of temperatures. Within the framework of the Van der Waals capillarity theory, using the quasiclassical Wigner expansion, we have obtained an expression for the surface tension of a liquid with weak quantum effects.
Investigation of the maximum superheating of liquid neon
Authors: Baidakov V. G.
Published: December 2024

The paper presents the results of measurements of the temperatures of superheating attainable at nearly atmospheric pressures of up to 0.6 pc. The experimental data are compared with the results of the classical homogeneous nucleation theory. The process of nucleation in liquid neon on a subsystem of electronic bubbles is considered. Using Wigner’s quasiclassical expansion, we obtain an expression for the spinodal and determine the limit of spontaneous boiling of a liquid with weak quantum effects. Data on the maximum superheating of cryogenic liquids are generalized within the framework of the quantum-mechanical law of corresponding states.
Coupled electromagnetic and acoustic waves in a compensated metal plate
Authors: Zherebchevskii D. É.
Published: December 2024

The distribution of the field of coupled electromagnetic and acoustic waves in a compensated metal plate in a magnetic field perpendicular to the surface is investigated. It is shown that coupling of the waves not only alters the spectrum of the acoustic and electromagnetic waves, but also endows the electromagnetic and acoustic fields with four modes: skin (Alfvén), doppleron, acoustic, and Gantmakher–Kaner modes. The spectrum of coupled normal modes is calculated, along with the magnitude and distribution of the field of each mode in the cases of excitation by an external acoustic wave and by an external electromagnetic wave. The relative variation of the acoustic, doppleron, and Gantmakher–Kaner components in the vicinity of the doppleron–phonon and Doppler-shifted cyclotron resonances are discussed.
Magnetoresistance anomalies in the region of spin-flip transitions in metamagnetic ErGa2
Authors: Baranov N. V. , Deryagin A. V. , Markin P. E. , Sinitsyn E. V.
Published: December 2024

Peaks were observed in the longitudinal magnetoresistance in metamagnetic ErGa2 when a two-phase magnetic state existed during spin–flip transitions. The value of the current flowing through a single phase boundary is theoretically predicted to be asymmetric relative to the sign of the potential difference applied across the boundary.
Relaxation of parametrically excited spin waves in ferrites at low temperatures
Authors: Zhitnyuk V. S. , Melkov G. A.
Published: December 2024

We have shown experimentally that the relaxation of a system of parametrically excited spin waves in ferrites is described by two characteristic frequencies, one describing amplitude damping of the spin waves, and the other describing their dephasing.
Electron localization and conductivity of discontinuous bismuth films
Authors: Butenko A. V. , Bukhshtab E. I. , Pilipenko V. V.
Published: December 2024

We report an anomalous positive magnetoresistance observed in thin discontinuous bismuth films in a magnetic field 1 <H < 17 kOe, which is well described by weak localization theory. It is found that the quantity ΔR/R is independent of the total resistance of the samples. The two-dimensional analog of the specific resistivity, R□, is the same for samples of various thicknesses near the current threshold, while the total resistance changes by almost two orders of magnitude, depending on the geometry of the conducting path.
Discrete resistive states of superconducting channels in electromagnetic fields with different frequencies
Authors: Dmitriev V. M. , Zolochevskiĭ I. V. , Khristenko E. V.
Published: December 2024

The results of an experimental investigation of the resistive states of a superconducting channel in a uhf field are presented. It is established that as the irradiation power increases, discrete resistive states appear in the sample, and their number decreases with increasing irradiation frequency. It was found that under certain conditions the change in the number of discrete resistive states in the sample is accompanied by the formation of a nonequilibrium normal state in the sample. The observed features are associated with the features of the relaxation of the population unbalance in the branches of the quasiparticle spectrum in electromagnetic fields.
Theory of the Josephson effect in SNINS and SNIS tunnel structures
Authors: Golubov A. A. , Kupriyanov M. Yu. , Lukichev V. F.
Published: December 2024

A microscopic theory of the Josephson effect is developed for low-transparency tunnel junctions in which one or both electrodes are SN sandwiches. A parameter γM, describing the strength of the proximity effect in the SN electrodes, is introduced and the components of the tunneling current through the junction are calculated numerically for a series of γM values over the entire temperature range 0 ≤ T ≤ Tc. We show that when the spatial dependence of the order parameter in the S region is taken into account, the results deviate significantly from the predictions of the McMillan tunneling model of the proximity effect. The results of calculations are in good agreement with experimental data for niobium-based tunnel junctions.
Influence of a magnetic field on superconducting fluctuations above T
c in cold-deposited indium films doped with hydrogen or oxygen
Authors: Belevtsev B. I. , Fomin A. V.
Published: December 2024

In this paper we investigate how a magnetic field affects the transition we detected earlier1 from two-dimensional to zero-dimensional fluctuations of the order parameter with increasing temperature in the region T > Tc for cold-deposited indium films containing hydrogen or oxygen impurities. The investigations show that as the magnetic field increases the critical region of zero-dimensional fluctuations grows in size and the reduced temperature ϵt(H) = ln(T/Tc) of this transition decreases, i.e., the temperature range in which two-dimensional fluctuations exist decreases. This behavior is consistent with the theoretically predicted change in the dimensionality of the fluctuations under the influence of the magnetic field.
Effects of high-frequency rectification in point contacts between normal metals
Authors: Kulik I. O. , Omel’yanchuk A. N. , Tuluzov I. G. , Sarkisyants T. Z.
Published: December 2024

The nonlinear uhf effects remaining in point contacts between normal metals up to frequencies of ω ∼ 1013−1014 sec−1 and temperatures of T ≲ 102 K are studied. The dependences of the rectified signal δI(V) = Ī(V) − I0(V) under laser irradiation of the contact on the frequency and the voltage applied to the contact are found in a microscopic theory (using the Green–Keldysh functions). Calculated numerically for a number of frequencies and temperatures, they agree satisfactorily with the results of experimental studies [R. W. Van den Heijden et al., Appl. Phys. Lett. 37, 245 (1980)].
Dynamics of a two-dimensional electron crystal with screened interaction and stability of a charged helium film
Authors: Vil’k Yu. M. , Monarkha Yu. P.
Published: December 2024

We study the dynamics of a two-dimensional electron crystal with screened interaction. This system can be produced by surface electrons on a helium film covering a metal substrate. The collective excitation spectrum of this crystal is computed by the Ewald method using an arbitrary screening parameter (the ratio of twice the film thickness to the lattice constant). The results are used to determine the stability of a charged helium film over a metal substrate. We find the stability condition for this film and the critical electron density at which the film stability breaks down.
Transport properties of NbSe3 (Hall effect)
Authors: Dolgov E. N.
Published: December 2024

It is shown within the framework of a model with nesting quasi-one-dimensional Fermi surfaces that the contribution of the free Fröhlich mode to the Hall constant near the Peierls transition temperature can cancel out the quite large anomaly in the Hall constant, as a result of which a Hall emf is produced. The applicability of the formulated model to the description of a real NbSe3 sample is discussed.
Low-temperature properties of quasi-one-dimensional magnetic systems with an XY interaction
Authors: Ezerskaya E. V.
Published: December 2024

The effect of the interaction between XY chains on the spectrum of low-lying excitations of quasi-one-dimensional magnetic systems has been investigated. It has been shown that the energies of two-magnon bound states of a tube of three XY chains lie beyond the continuous spectrum for sufficiently high values of the total quasimomentum while the energies of the analogous states for a strip containing the same number of chains always belong to the continuous spectrum.
Magnetoresistance of aluminum on plastic deformation
Authors: Gostishchev V. I. , Dem’yanov S. E. , Sobol’ V. R.
Published: December 2024

An increase in the relative transverse magnetoresistance as a function of deformation, produced by small angle electron scattering by extended defects in the crystal lattice, was found in galvanomagnetic measurements on aluminum. Two forms of small angle scattering are compared: electron–phonon and electron–dislocation.
Observation of weak superconductivity in electrons localized on a film surface
Authors: Fogel’ N. Ya. , Kolin’ko A. E.
Published: December 2024

We have observed anomalous abrupt resistance changes in thick vanadium films [d≫ξ(T)]. We have also observed a number of anomalies in the H–T phase diagrams for these films; these anomalies are most clearly seen when the field is parallel to, or at low angles of incidence with respect to, the film surface. We explain our results by assuming that there are two different electron systems present in the film. One of them is composed of electrons localized near a natural planar defect, the film surface. This subsystem is characterized by extremely small values of the critical current.
Theory of the mutual influence of excitonic and superconducting phase transitions
Authors: Tonchev N. S. , Brankov I. G.
Published: December 2024

The Landau expansion for the grand thermodynamic potential in the neighborhood of a point at which the temperature of a purely superconducting transition is approximately equal to the temperature of a purely dielectric phase transition is analyzed for a class of mean-field models used in the study of the mutual influence of electron–hole and Cooper pairs. It is shown that the competition between the dielectric and superconducting phases suppresses one of the phase transitions against the background of the other.
One type of disorder in layered and granular superconductors
Authors: Gvozdikov V. M.
Published: December 2024

The density of states and the dependence of the critical temperature on l in a layered superconductor, divided in a random manner by linear chains of impurities into strips with average width l, are calculated. The relation to experiment is discussed. The density of states in a related system—a granular superconducting film consisting of granules with random sizes—is studied.
On the nature of the yield stress of metallic glasses
Authors: Akhiezer I. A. , Davydov L. N. , Spol’nik Z. A.
Published: December 2024

The temperature dependence of the yield stress of metal–metalloid glasses is analyzed on the basis of the dynamic model of Bernal–Polk complexes. The experimental data suggest preference should be given to one version of the model, viz., the soft-frame model in which the activation energy of dissociation of complexes is of the order of the melting point of the substance.
Anisotropy of point-contact noise spectra in copper
Authors: Akimenko A. I. , Verkin A. B. , Yanson I. K.
Published: December 2024

The point-contact noise spectra of copper have been measured for the [100], [111], and [110] directions. The noise spectra have been found to be appreciably anisotropic while the point-contact spectra are weakly anisotropic. The growth of the noise has been shown to have a threshold nature which is attributed to electron–phonon processes being switched on at the corresponding energies.
Excitation anisotropy of coupled spin-vibration branches in antiferromagnetic CuCI2·2H2O
Authors: Dan’shin N. K. , Zel’tser A. S. , Popov V. A.
Published: December 2024

We present an experimental and theoretical study of the homogeneous spin–spin resonance in the antiferromagnet CuCl2 · 2H2O. We establish experimentally that the branches of the spin–spin resonance in a magnetic field lie near the intermediate axis for T = 1.65 K. Analytical expressions are obtained for the coupled frequencies for the cases where the field is inclined in the ab, ac, and bc planes of the crystal. The value of the components gb and gc of the anisotropic g-factor are determined for the ordered state.
Experimental vacancy-formation parameters for atomic cryocrystals
Authors: Bondarenko A. I. , Gavrilko V. G. , Popov V. A.
Published: December 2024

The thermal expansion coefficients of solid argon have been measured in the temperature range from 65 to 82 K. The volume, entropy, and enthalpy of vacancy formation have been calculated on the basis of the known thermal expansion coefficients of inert-gas crystals, measured using macroscopic and x-ray techniques. The thermal expansion data have been used to determine the thermal properties of solid argon in the premelting temperature range.
Critical current in high-resistance Josephson SNS sandwiches
Authors: Lukichev V. F.
Published: December 2024

A simple analytic formula is obtained, within the framework of the microscopic equations of superconductivity in the dirty limit, for the critical current of extended (L⪢ξN) quasi-one-dimensional Josephson SNS sandwiches with high-resistance material for the interlayer at arbitrary temperatures.
Low-temperature specific heat of a globular protein: human serum albumin
Authors: Verkin B. I. , Blagoi Yu. P. , Gurevich A. M. , Eropkin V. N.
Published: December 2024

The specific heat of a globular protein—human serum albumin with a water content of 6−10 wt. %—is measured in the temperature range 1.8−25 K. Below 4 K the specific heat is described by the sum of a cubic term and a linear term with respect to the temperature; the linear contribution to the specific heat is dominant below 1 K. This type of function C(T) corresponds to the glassy protein model proposed by Gol’danskii et al. A singularity of the specific heat is observed in the temperature interval 2.6−4.1 K. The presence of several specific-heat maxima can be attributed to structural changes taking place in the protein globule.
Plasmon-enhanced photo/electrocatalysis: Harnessing hetero-nanostructures for sustainable energy and environmental applications
Authors: Tufa Lemma Teshome , Gicha Birhanu Bayissa , Molla Cheru Fekadu , Nguyen Huu-Quang , Tran Van Tan , Nwaji Njemuwa , Hu Xiaojun , Chen Hongxia , Lee Jaebeom
Published: December 2024

Plasmon-enhanced photo/electrocatalysis using hetero-nanostructures has emerged as a promising approach for boosting the efficiency and selectivity of photo/electrocatalytic reactions. Plasmonic nanostructures (PNSs), with their unique properties including localized surface plasmon resonance (LSPR), play a vital role in enhancing photo/electrocatalytic activities. By leveraging LSPR, PNSs can concentrate incident light, facilitate charge separation, and induce surface reactions, leading to improved catalytic performance. In this review, we provide a comprehensive analysis of the current state of knowledge in this field. We discuss the rational design and synthesis of hetero-nanostructures, focusing on the optimization of composition, size, shape, and interface properties. Furthermore, we explore various combinations of plasmonic sources with semiconductors of diverse morphologies to achieve enhanced photocatalytic activity. The reviewed research encompasses applications in water splitting, removal of organic pollutants, CO2 reduction, and energy conversion. We also address the challenges that need to be overcome, including optimization of materials, reproducibility, stability, band alignment, and understanding plasmon–material interactions in hetero-nanostructures. The review of future perspectives includes the integration of multiple functionalities, the exploration of novel plasmonic materials, and the translation of plasmon-enhanced photo/electrocatalysis into practical applications. The combination of plasmonics and nanotechnology can be used to advance green technologies and address pressing global issues.
Anomalous diffusion model in Fourier space describing time correlation of shear Alfvénic turbulence
Authors: Nariyuki Y.
Published: December 2024

Time-correlation function in shear Alfvénic turbulence is examined from the point of view of stochastic dynamics in Fourier space. The complex random oscillator model for Elsasser variables, which has been used to discuss the violation of the Taylor hypothesis, is revisited. By using Fourier phase diffusion obeying the scaled Brownian motion, the generalized random oscillator model is derived. Auto- and cross-correlations given by the resultant model indicate that the characteristics (parameters) of anomalous diffusion of Fourier phase are closely related to the residual energy, while the cross-helicity is directly given by the energy portion among Elsasser variables. The stochastic uncertainty of the Fourier amplitude is also incorporated by taking the approach of the stochastic growth theory into account, resulting in the generalized model including terms that mimic both local and non-local interactions.
Disseminable single-photon source for quantum radiometry
Authors: Georgieva Hristina , Gerrits Thomas , Ma Lijun , Dawkins Riley , López Marco , Slattery Oliver , Kanold Niklas , Kaganskiy Arsenty , Rodt Sven , Reitzenstein Stephan , Migdall Alan , Kück Stefan
Published: December 2024

We present a disseminable single-photon source based on an InGaAs quantum dot in a micro-mesa. This source achieves a maximum photon flux of (2.74 ± 0.03) × 106 photons/s at a wavelength of (929.7 ± 0.1) nm, with a multiphoton suppression of g(2)(0) = 0.22 ± 0.02. The semiconductor chip can be installed in any cryogenic system and the compact size of all optical components facilitates easy dissemination for interlaboratory comparisons. The consistency in results regarding single-photon purity and the similarity of the measured photon fluxes across two distinct laboratory environments underscores the robustness and versatility of this single-photon source, which shows its potential to be used as a standard source for interlaboratory comparisons in quantum radiometry.
Synchronization cluster bursting in adaptive oscillator networks
Authors: Wei Mengke , Amann Andreas , Burylko Oleksandr , Han Xiujing , Yanchuk Serhiy , Kurths Jürgen
Published: December 2024

Adaptive dynamical networks are ubiquitous in real-world systems. This paper aims to explore the synchronization dynamics in networks of adaptive oscillators based on a paradigmatic system of adaptively coupled phase oscillators. Our numerical observations reveal the emergence of synchronization cluster bursting, characterized by periodic transitions between cluster synchronization and global synchronization. By investigating a reduced model, the mechanisms underlying synchronization cluster bursting are clarified. We show that a minimal model exhibiting this phenomenon can be reduced to a phase oscillator with complex-valued adaptation. Furthermore, the adaptivity of the system leads to the appearance of additional symmetries, and thus, to the coexistence of stable bursting solutions with very different Kuramoto order parameters.
Effects of temperature anisotropy on the flow-driven Alfvén wave instabilities in interpenetrating plasmas
Authors: Ramzan Saba , Abbas G. , Iqbal Z. , Zeba I.
Published: December 2024

Flow-driven electromagnetic instabilities play a critical role in various space plasma environments. Utilizing linearized Vlasov–Maxwell model equations, this paper examines the dispersion relations of drifting Alfvén waves under the influence of temperature anisotropy. The study identifies significant modifications in the combined drifting Alfvén modes compared to previous research. The positive (P) and negative (N) solutions, which represent coupled flow-driven Alfvén modes, reveal threshold values for normalized streaming velocity, demarcating the transition between real and imaginary frequency spectra, and emphasize the impact of ion temperature anisotropy. The analysis discusses the role of fast-moving ions in developing instability, considering the effects of density ratios and streaming velocities. When the densities of interpenetrating plasmas are equal and the merging point ωs+f of the solutions is identified, the influence of ion temperature anisotropy on the P-N Alfvén modes is particularly notable in different low plasma beta regions. However, for fixed ion streaming velocities, varying densities and ion temperature anisotropy in the range T∥>T⊥ cause the modes to become finite forward while they become infinitely forward when T∥<T⊥. This investigation provides insights into the behavior of Alfvén waves in interpenetrating plasmas and sheds light on electromagnetic wave instability mechanisms in such interpenetrating plasmas.
High reflectance ultrashort period W/B4C x-ray multilayers via intermittent ion polishing
Authors: IJpes D. , Yakshin A. E. , Ackermann M. D.
Published: December 2024

Ultrashort period W/B4C multilayers (MLs) are essential for high-resolution x-ray optics, but their performance is limited by inherent interface roughness. In this study, we introduced the technique of intermittent ion beam polishing (I-IBP) to sputter-deposited W/B4C MLs with 1.0 and 1.1 nm periods. This novel approach differs from traditional ion polishing by using polished B4C interlayers to disrupt the accumulation of roughness throughout the multilayer. The 1st Bragg peak reflectance doubled compared to non-polished W/B4C, reaching 20% at λ = 0.154 nm (φBr=3.9° grazing) and 8.4% at λ = 0.834 nm (φBr=22° grazing) for 1.1 nm W/B4C. The average interface width decreased from 0.27 to 0.22 nm, which is attributed to interface smoothing. X-ray diffuse scattering and STEM images showed reduced interface roughness and improved lateral and vertical correlation lengths. This study demonstrates that I-IBP significantly enhances the structural and optical properties of ultrashort period MLs, advancing ML-based optics for both soft and hard x rays.
An ultra-high vacuum scanning tunneling microscope with pulse tube and Joule–Thomson cooling operating at sub-pm
z
-noise
Authors: Eßer Marcus , Pratzer Marco , Frömming Marc , Duffhauß Jonas , Bhaskar Priyamvada , Krzyzowski Michael A. , Morgenstern Markus
Published: December 2024

Low-temperature scanning tunneling spectroscopy is a key method to probe electronic and magnetic properties down to the atomic scale, but suffers from extreme vibrational sensitivity. This makes it challenging to employ closed-cycle cooling with its required pulse-type vibrational excitations, albeit this is mandatory to avoid helium losses for counteracting the continuously raising helium prices. Here, we describe a compact ultra-high vacuum scanning tunneling microscope (STM) system with an integrated primary pulse tube cooler (PTC) for closed-cycle operation. It achieves temperatures down to 1.5 K via a secondary Joule–Thomson stage and a z-noise down to 300 fmRMS in the STM junction for the frequency range of 0.1 Hz–5 kHz (feedback loop off). This is better than many STMs cooled by an external supply of liquid helium. The challenge to combine an effective vibrational decoupling from the PTC with sufficient thermal conduction is tackled by using a multipartite approach including the concept of bellows with minimal stiffness to decouple the PTC vibrationally from the STM and an optimized STM design with minimal vibrational transfer to the STM junction. As important benchmarks, we could reduce the voltage noise in the tunnel junction down to 120 μV and supply radio frequency excitations up to 40 GHz with amplitudes up to 10 mV in the junction via a close-by antenna. The development principally enables other secondary cooling stages such that it opens the perspective for a helium conserving operation of STMs across the whole interesting temperature range.
The kinetic analog of the pressure–strain interaction
Authors: Conley S. A. , Juno J. , TenBarge J. M. , Barbhuiya M. H. , Cassak P. A. , Howes G. G. , Lichko E.
Published: December 2024

Energy transport in weakly collisional plasma systems is often studied with fluid models and diagnostics. However, the applicability of fluid models is limited when collisions are weak or absent, and using a fluid approach can obscure kinetic processes that provide key insights into the physics of energy transport. Kinetic diagnostics retain all of the information in 3D-3V phase space and thereby reach beyond the insights of fluid models to elucidate the mechanisms responsible for collisionless energy transport. In this work, we derive the Kinetic Pressure–Strain (KPS): a kinetic analog of the pressure–strain interaction, which is the channel between flow energy density and internal energy density in fluid models. Through two case studies of electron Landau damping, we demonstrate that the KPS diagnostic can elucidate kinetic mechanisms that are responsible for energy transport in this channel, just as the related field–particle correlation is known to identify kinetic mechanisms of transport between electromagnetic field energy density and kinetic energy density in particle flows. In addition, we show that resonant electrons play a major role in transferring energy between fluid flows and internal energy during the process of Landau damping.
Measurement of electron density in high-pressure plasma using a microwave cutoff probe
Authors: Park Seong-Bin , Yeom Hee-Jung , Hwang Do-Yeon , Kim Young-Joo , Lee Hyo-Chang , Kim Jung Hyung
Published: December 2024

Despite the widespread applications of high-pressure plasma in semiconductor and display industry, such as deposition and ashing process, the use of cutoff probes for diagnosing high-pressure plasma was rarely studied. In this study, we investigated a method of measuring electron density in a cutoff probe using the resonance peak in a high-pressure plasma environment. This method is validated through both electromagnetic wave simulations and experimental methodologies. Our findings reveal that the proposed method demonstrates discrepancies of less than 1.47% compared to the input plasma frequency in the results of electromagnetic wave simulations at a gas pressure of 10 mTorr, while at 2.5 Torr, it exhibited a maximum discrepancy of 13.3% when selecting resonance frequencies lower than the electron–neutral collision frequency. This discrepancy at high pressure is reduced to within 1.92% by selecting a resonance frequency higher than the electron–neutral collision frequency. Also, the feasibility of these electron density measurements has been confirmed under conditions of high gas pressure where the cutoff frequency is not measurable, as evidenced by both simulation and experimental results. Our research on the diagnostic methods in high-pressure plasmas could significantly enhance the measurement and interpretation of plasma parameters in various industrial processes.
Ultrafast photoconductivity dynamics in narrow-gap HgCdTe films
Authors: Refvik N. B. , Purschke D. N. , Jensen C. E. , Pan W. , Simpson H. R. J. , Lei W. , Gu R. , Antoszewski J. , Umana-Membreno G. A. , Faraone L. , Hegmann F. A.
Published: December 2024

Mercury cadmium telluride (Hg1−xCdxTe or MCT) is the premier material for infrared detection. However, despite its importance, studies exploring the ultrafast photoresponse in this semiconductor alloy are limited. Here, we use time-resolved terahertz spectroscopy to perform a detailed study of the picosecond charge carrier dynamics in long-wave infrared Hg1−xCdxTe (x ∼ 0.2) films, providing insight into ultrafast carrier cooling and temperature-dependent scattering mechanisms. Due to the multilayer photoexcited sample geometry, an elementary thin-film analysis leads to a negative photoconductivity artifact. We, therefore, derive a modified thin-film photoconductivity formula to accurately extract a Drude photoconductivity spectrum. In our analysis, we include the effects of carrier diffusion and the conduction band non-parabolicity in Hg1−xCdxTe. We extract ultrahigh electron mobilities as large as 6 × 105 cm2 V−1 s−1 at 25 K. At cryogenic temperatures, we find the photoexcited electron mobility is up to four times larger than the dark mobility, which we attribute to suppression of ionized impurity scattering due to hole capture by acceptor-type Hg vacancies. In addition, after photoexcitation, we observe a relatively slow rise in photoconductivity over a 10 ps timescale with a monotonically increasing carrier scattering time and a carrier effective mass that decays exponentially with a time constant of 1.9 ps, which we attribute to hot-carrier cooling dynamics in the non-parabolic conduction band.
Dynamical modeling and experimental research on capillary flow of gallium-based liquid metal for reconfigurable structures
Authors: Jiang Chuanyang , Li Xiangpeng , Guo Kaixuan , Yang Sheng , Yu Jiao , Cao Lu , Tan Wenchang , Li Faxin
Published: December 2024

Gallium and its alloys, as emerging multifunctional metals that melt at room temperature, hold strategic significance in advanced manufacturing and technological innovation. By uniquely integrating the exceptional electrical conductivity of metals with the intrinsic fluidity of liquids, gallium-based liquid metals have garnered immense interest from both academic researchers and industrialists with a wide range of potential applications, including stretchable wires, self-healing circuits, 3D printing and patterning, and reconfigurable antennas. These remarkable properties enable groundbreaking approaches to the patterning and manipulation of gallium-based liquid metals, facilitating the fabrication of reconfigurable and stretchable structures with an unparalleled combination of electrical and mechanical performance. However, an essential yet still unaddressed issue is to establish the quantitative relationship between the interface position of the liquid metal column and the corresponding time of motion. In this study, we have developed a dynamical model based on the momentum theorem and conducted experimental verifications to investigate the capillary flow of gallium-based liquid metals. Our results demonstrate that the theoretical calculations of the time required for eutectic gallium indium to flow from the inlet to the outlet of capillary tubes are in good agreement with experimental measurements obtained from capillary tubes of varying lengths. Consequently, the dynamical model presented here provides quantitative theoretical insights, serving as a valuable tool for guiding the design and fabrication of reconfigurable liquid metal structures and devices in the future.
Dynamical modeling and analysis of epileptic discharges transition caused by glutamate release with metabolism processes regulation from astrocyte
Authors: Li Duo , Li Qiang , Zhang Rui
Published: December 2024

Glutamate (Glu) is a crucial excitatory neurotransmitter in the central nervous system that transmits brain information by activating excitatory receptors on neuronal membranes. Physiological studies have demonstrated that abnormal Glu metabolism in astrocytes is closely related to the pathogenesis of epilepsy. The astrocyte metabolism processes mainly involve the Glu uptake through astrocyte EAAT2, the Glu–glutamine (Gln) conversion, and the Glu release. However, the relationship between these Glu metabolism processes and epileptic discharges remains unclear. In this paper, we propose a novel neuron-astrocyte model by integrating the dynamical modeling of astrocyte Glu metabolism processes, which include Glu metabolism in astrocytes consisting of the Glu uptake, Glu–Gln conversion, Glu diffusion, and the resulting Glu release as well as Glu-mediated bidirectional communication between neuron and astrocyte. Furthermore, the influences of astrocyte multiple Glu metabolism processes on the Glu release and dynamics transition of neuronal epileptic discharges are verified through numerical experiments and dynamical analyses from various nonlinear dynamics perspectives, such as time series, phase plane trajectories, interspike intervals, and bifurcation diagrams. Our results suggest that the downregulation expression of EAAT2 uptake, the slowdown of the Glu–Gln conversion rate, and excessively elevated Glu equilibrium concentration in astrocytes can cause an increase in Glu released from astrocytes, which results in the aggravation of epileptic seizures. Meanwhile, neuronal epileptic discharge states transition from bursting to mixed-mode spiking and tonic firing induced by the combination of these abnormal metabolism processes. This study provides a theoretical foundation and dynamical analysis methodology for further exploring the dynamics evolution and physiopathological mechanisms of epilepsy.