bluuebunny/crossref_metadata_2025 huggingface dataset:
Geological Modeling of the Senonian Aquifer in the Oued Guir Watershed (Southeast Morocco)
Authors: Messaoudi Badre , Kabiri Lahcen , El Ouali Mohamed , Ait Lahssaine Ismail , Kadiri Abdelhakim , Essafraoui Badre
Published: January 2025

The Oued Guir watershed in southeast Morocco stretches widely from the High Atlas in the north to the Hamadas in the south. This basin is characterized by an arid climate strongly influenced by continental conditions. The Lower Guir has become a focal point for the development of modern agriculture following the launch of the Green Morocco Plan. This has led to increased overexploitation of groundwater, specifically the shallow Senonian aquifer. The objective of this study is to model the geological formations of the Senonian aquifer using the Geological Modeling System and GIS software, based on drillings and wells data to understand better the distribution of geological formations and hydraulic characteristics of this aquifer. The obtained geological model shows lateral and vertical variations of the facies and thickness of the Senonian formations. The facies change between clays, silts, and sands, while the thickness exceeds 650 meters. From a hydrodynamic point of view, the transmissivity of this aquifer varies between 0.11 × 10−4 and 7.2 × 10−4 m2/s, with an average of 3.65 × 10−4 m2/s. These characteristics play a crucial role as aquifers in the basin that ensure water resources of the Boudnib area.
A new index for extracting built-up land features using Landsat satellite imagery
Authors: Jellouli Amine , Chakouri Mohcine , El Hachimi Jaouad , Hajaj Soufiane , Jari Abdessamad , Adiri Zakaria
Published: January 2025

Land features mapping in urban regions are changing rapidly over time as a result of continuous urbanization. Spatial remote sensing allows continuous monitoring of this change using multi-date image data and providing a synoptic view. In light of this, a new spectral index based on pre-existing indices is suggested for the purpose of extracting built-up features in the Beni Mellal study area utilizing two Landsat-5 TM and Landsat-8 OLI images from 2013 and 2023. This time range of ten years enables the spatial and temporal monitoring of built-up surfaces. The accuracy of the results obtained is confirmed by using Pearson's correlation to land surface temperature and the two spectral indices, the Normalized Difference Moisture Index (NDMI) and Normalized Difference Vegetation Index (NDVI).
Utilizing Remote Sensing to Quantify Evapotranspiration: A Case Study of the Saiss Basin (Morocco)
Authors: Oumou Abdellah , Essahlaoui Ali , Khrabcha Abdelali , Essahlaoui Narjisse , Alitane Abdennabi , Kassou Amina , El Hafyani Mohammed , Van Rompaey Anton , Gobin Anne
Published: January 2025

In areas highly affected by drought in a changing climate, evapotranspiration (ET) becomes a significant parameter affecting soils and vegetation. ET estimation on a large scale remains a problem in understanding the hydrologic system; it is complicated over heterogeneous land use and land cover. However, the availability of remote sensing imagery and local weather data has made ET mapping possible through the application of models. In this study, the METRIC model was applied using Landsat satellite imagery and climatic data. This involves resolving the surface energy balance equation by calculating net radiation, soil heat flux, and sensible heat flux. Two satellite images were used at a resolution of 15m: one for January as a wet season and another for July as a dry period. ET ranges between 2 and 12 mm/day. Higher values are estimated during the dry period, and lower values are attributed to the wet period. Furthermore, water bodies and vegetation are characterized by significant ET compared to bare soils and urbanized areas. The comparison of METRIC ET and reference ET showed a strong correlation with an R², RMSE, and MAE of 0.68, 1.0, and 0.78, respectively. This study can assist managers in their water and agricultural adaptation strategies against climate change.
Automatic Coastline Detection Using Coastsat Toolbox and GIS: A Case Study at Oued-Laou Beach, Morocco
Authors: Souiri Smail , Hakkou Mounir , Haddaoui Hatim , Oubdil Soufiane , Lmrimed Nargiss
Published: January 2025

Coastal zones are vital ecosystems increasingly impacted by erosion and human activities. Accurate and timely shoreline mapping is essential for understanding coastal dynamics, predicting erosion, and guiding sustainable management strategies. This study presents an automatic approach for coastline detection using the CoastSat toolbox and GIS tools, applied to Oued-Lou Beach, Morocco. By analyzing publicly available satellite imagery spanning over 30 years, the study generated detailed coastline maps over a 23-year period, revealing significant spatial and temporal variations in shoreline changes. Analysis with the Digital Shoreline Analysis System (DSAS) showed significant erosion along the entire coastline, with the most severe erosion observed around the mouth of Oued-Laou, where erosion rates exceeded -2 m/year. In contrast, the northern sector experienced alternating periods of accretion (up to 0.5 m/year) and moderate erosion (around -0.5 m/year). The southern sector showed accretion rates ranging from 0.5 m/year to 1 m/year, while the area between OL5 and Cap Targha exhibited substantial erosion exceeding -1 m/year. These findings highlight the need for tailored management strategies to mitigate erosion and promote sustainable development in this coastal region.
Preliminary experimental analysis of a CdTe BIPV skylight on a lab-scale test cell
Authors: Pop Octavian-Gabriel , Mustafa Elmakki Ali Elmakki , Lăcrănjan Mircea , Fechete-Tutunaru Lucian
Published: January 2025

The recent goal of developing new solar energy-harvesting methods has led to the study and implementation of Building Integrated Photovoltaic (BIPV) glazing structures integrated into building envelopes. Thus, currently, the most energy-efficient substitute for traditional building glazing components is the BIPV window; however, to achieve a wide level of implementation, research is still required. This paper presents an experimental test chamber designed to investigate the effectiveness of a semi-transparent BIPV glazing skylight with a 40% degree of transparency. Weather parameters were monitored using a laboratory-manufactured weather station. At its peak, the PV power output is 36.78 W, at a global solar irradiance of 573.69 W/m2. Values of 67.25 °C were displayed by temperature sensors mounted on the outer glazing surface. The air temperature reached high values near the globe thermometer signals because of the small test cell size and thermal insulation. The interior illuminance values during the operation stabilised at ~16.6 klx. The experimental data were compared with findings from related research. The ranges of the results obtained in the current study matched those of previous research.
Exploring the impact of clothing insulation on thermal comfort evaluation using thermal manikins
Authors: Cernei Alexandru , Lacassagne Tom , Fagniez Thomas , Danca Paul , Georgescu Matei-Răzvan , Thevenet Frédéric , Verriele Marie , Nastase Ilinca
Published: January 2025

Thermal manikins are valuable tools used in advancing our understanding of thermal comfort. This study examines the effect of varying clothing insulation on the predicted degree of thermal comfort using a thermal manikin named MONICA (MONitoring Indoor Comfort and Air quality). The experiments were conducted in a controlled climate chamber with the room temperature maintained at 24 °C. Three different clothing configurations were tested: naked, summer clothes (0.2 clo), and winter office clothes (0.7 clo). The equivalent temperature was measured for each configuration and compared to the Predicted Mean Vote (PMV) values obtained simultaneously. Additionally, the study utilized the Background Oriented Schlieren (BOS) technique to visualize the thermally driven airflow around the manikin. The findings from this study confirm the effectiveness of the thermal manikin in simulating human thermal responses and provide valuable insights into the role of clothing insulation in thermal comfort assessments. The obtained results will be useful for choosing the right clothing insulation for future thermal comfort assessments with the manikin.
Seat-integrated Personalized Ventilation Diffuser for Improving Air Quality Aboard Commercial Aircraft
Authors: Georgescu Matei-Razvan , Danca Paul , Cosoiu Costin Ioan , Bode Florin , Nastase Ilinca
Published: January 2025

Current commercial aircraft ventilation design focuses on space optimization and pressure-related safety parameters. It inadequately takes into account the impact of the mixing ventilation system on pathogen dispersion in an enclosed space with low humidity. Current international guidelines relating to pathogen transfer reduction, suggest a combined approach using both traditional mixing ventilation systems and personalized ventilation. The present paper studies the impact of seat-integrated personalized ventilation diffusers on the air quality in the passenger breathing zone. The study employs an experimental setup backed by numerical simulations to evaluate the system’s potential to disperse pollutants near the breathing zone. Human thermal manikins were used to simulate the passengers in a full-scale mock-up of the airplane cabin. The velocity fields of the personalized ventilation diffusers and the thermal plume have been measured using PIV techniques. The experimental results were used to validate the CFD scenarios. The numerical part of the study used exhaled CO2 accumulation in the breathing zone to assess the effectiveness of the PV diffusers. Results indicate that the presence of the PV diffusers directs the exhaled CO2 upwards and can act as a barrier preventing pathogens from entering the breathing zone.
Assessment of Freeze-Thaw in Romania
Authors: Arion Cristian , Vacareanu Radu , Aldea Alexandru , Arion Andrei , Pavel Florin
Published: January 2025

Due in part to political participation, the study of severe climate and weather conditions has attracted a lot of attention in recent decades. However, there has been insufficient focus on the historical climate monitoring data. Accurate estimates of frost heave are crucial for determining construction costs, designing building foundations, and ensuring the integrity of concrete structures. Additionally, frost heave plays a significant role in local meteorological conditions, impacting perennial plants. To mitigate the effects of freeze-thaw cycles on concrete, various strategies must be employed during the design, construction, and maintenance phases. The results from this investigation could be applied to mitigate frost-related disasters and inform the development of policies and measures for adapting geotechnical and structural designs to the specific conditions of Romania. Also, the paper presents the calculations of winter severity parameters for the city of Cluj-Napoca. A Romanian freeze-thaw cycle (FTC) map is essential due to recent climate studies showing an increase in both global and local surface temperatures, with the past thirty years seeing the most notable warming.
Gas dynamics of quasiparticles. II. Kinetic coefficients in transport equations for quasiparticles
Authors: Akhiezer A. I. , Aleksin V. F. , Khodusov V. D.
Published: January 2025

The kinetic coefficients in hydrodynamic equations for phonons, magnons, and their mixtures are calculated. Special functions and systems of orthogonal polynomials constructed on the basis of the weight function typical of Bose–Einstein statistics are used.
Relaxation kinetics for nonequilibrium quasiparticle excitations in antimony point contacts
Authors: Balkashin O. P. , Kulik I. I.
Published: January 2025

The high-frequency point-contact spectroscopy technique is used for studying antimony contacts in the interval 3·103 − 8·1010 Hz. It is shown that the main contribution to the background signal in the PC spectrum is made by the processes of multiphonon relaxation of electrons, and not by the reabsorption of nonequilibrium phonons. The frequency of thermal relaxation of the point contact is determined from the frequency dispersion of the conductivity in the region of high voltages. The high-frequency results for contacts with inverse spectra are interpreted by using the model of spatial localization of electron states. A considerable enhancement of the spectral singularities of the electron-phonon interaction is revealed.
Dipole-dipole interaction in CsGd(MoO4)2
Authors: Anders A. G. , Volotskii S. V. , Startsev S. V. , Feher A. , Orendachova A.
Published: January 2025

The energy of dipole-dipole interaction is calculated for the rare-earth subsystem of CsGd(MoO4)2 and the magnetic structure of its ground state is determined. Temperature dependences of magnetic susceptibility and magnetic heat capacity for the paramagnetic region are calculated in the purely dipole approximation. A satisfactory agreement with experiments is achieved.
On the theory of phase transitions in conducting magnets
Authors: Ivashin A. P. , Krasil’nikov V. V. , Rozhkov A. A.
Published: January 2025

Various types of magnetic ordering (ferromagnetic, spiral, and modulated structures) in a system of electrons and localized spins are considered by using the Fermi-liquid approach, taking the RKKY interaction into account. Self-consistent equations are derived for the order parameters of magnetically ordered phases. These equations are used in the analysis of the first- and second-order phase transitions in the Landau theory. The phase diagram is constructed, and the conditions of existence of the ferromagnetic, spiral, and modulated phases are determined.
Dependence of the amplitude of magnetoquantum oscillations of the metallic point-contact resistance on the bias voltage
Authors: Bobrov N. L. , Gribov N. N. , Kokkedee Y. , Jansen A. G. , Wyder P. , Yanson I. K.
Published: January 2025

Magnetoquantum oscillations of resistance as functions of the potential difference applied across the contact are studied for metallic point contacts made of Al and Be. The amplitude of resistance oscillations in a magnetic field increases with voltage and is identical to the EPI spectrum of the point contact for one group of contacts, and with the bias voltage across the contact for another. The increase in the oscillation amplitude as well as its decrease has a nonmonotonic dependence on energy. The scattering of electrons by nonequilibrium phonons and the Fermi-liquid effects in the nonequilibrium electron system are considered as the possible reasons behind the observed effects.
Magnetodynamics of conduction electrons in AI in a nonuniform field
Authors: Mazurenko O. N. , Sobol’ V. R. , Drozd A. A.
Published: January 2025

The nature of charge transfer in metals is investigated experimentally and theoretically for Al in a transverse magnetic field. The nonuniformity along the charge flow is simulated by the of the “bent sample” method, which makes it possible to realize a linear and an exponential law of field variation for a relative gradient level of the order of 0.05−1 cm−1. Experimental results are analyzed on the basis of the continuity equation taking into account the linear dependence of magnetoresistance on the field.
Elastic moduli of La2−xSrxCuO4 single crystals. Anisotropy in the a–b plane
Authors: Bezuglyi E. V. , Burma N. G. , Kolobov I. G. , Fil’ V. D. , Vitebskii I. M. , Knigavko A. N. , Lavrinenko N. M. , Barilo S. N. , Zhigunov D. I. , Soshnikov L. E.
Published: January 2025

The elastic moduli have been measured in single crystals of the system La2−xSrxCuO4. Considerable anisotropy is observed in the elastic moduli of monodomainized samples with x = 0. For x = 0.13, jumps in the series of elastic moduli during tetra-ortho structural transformation are determined. The theory of elastic properties of multidomain samples is constructed.
Low-temperature strength and ductility of power compounds YBaCuO-Ag
Authors: Dolgin A. M. , Kislyak I. F. , Dotsenko V. I. , Zagoruiko L. N.
Published: January 2025

Strain-hardening curves and the nature of deformation of YBaCuO–Ag power compounds are studied in a wide range of Ag concentration (0⩽c⩽100%) at T = 77 K. It is found that the deformation curves can be divided into four groups determined by the Ag concentration. The concentration dependences of the deformation parameters σ0, σmax, and εmax are obtained. It is shown that silver can noticeably improve the technological properties of the HTS ceramic material by varying its deformation behavior considerably.
The collective mode spectrum in polar phase of superfluid 3He
Authors: Brusov P. N. , Lomakov M. V. , Brusova N. P.
Published: January 2025

Using the path integration technique, developed by Brusov and Popov earlier,1 we calculate the collective mode spectrum at zero momentum of excitations for polar phase of superfluid 3He. We found six modes with energy E = (1.20−1.75i) Δ0 which damp strongly and three Goldstone modes with zero energy at zero momentum of excitations.
A new kinetic effect under electron-electron collisions in two-dimensional electron gas
Authors: Gurzhi R. N. , Kalinenko A. N. , Kopeliovich A. I.
Published: January 2025

It is shown that the degenerate two-dimensional gas (2 DEG), along with the Poiseuille flow, can support a new hydrodynamic effect, associated with one-dimensional diffusion of charge carriers. As a result, the region of the inverse electrical resistivity vs temperature dependence expands considerably. It is likely that this effect was observed in the experiments of Molenkamp and de Jong.1
Interaction of d electrons of a magnetic ion with local distortions of the crystal structure (review)
Authors: Vasyukov V. N. , Sukharevskii B. Ya.
Published: January 2025

The existing crystal field theory used in calculating the energy spectrum of ions with an unfilled d shell does not make any provision for the influence of this ion on its nearest crystal environment. Based on an analysis of existing data in the literature, this survey shows that the influence of a magnetic ion on the crystal environment must be taken into account. An experimental procedure is discussed for investigating crystal structure distortions induced by the introduction of a magnetic impurity in the crystal. Existing experimental results from the study of the configuration of magnetic ion–ligand complexes are analyzed, and the measured angles of distortion of the first coordination sphere complex are compared with their calculated values. It is found that, regardless of the symmetry of the ground state, the interaction of electrons of the unfilled d shell have a decisive influence on the magnitude and sign of the structural distortion in the vicinity of the magnetic ion. The research results discussed in the survey, on the one hand, help to answer several previously unresolved questions in the theory of the crystal field and, on the other, reveal unexplored new areas.
Influence of an iron impurity on the superconducting properties of bismuth high-T
c superconducting ceramics
Authors: Korostin S. V. , Permyakov Yu. V. , Makarov E. F.
Published: January 2025

The influence of an iron impurity on the superconductivity of bismuth high-Tc superconducting ceramics is investigated by Mössbauer spectroscopy and magnetic susceptibility measurements. It is shown that iron is distributed among three positions, which are determined along with the solubility limit of iron in the host high-Tc superconductor. It is postulated on the basis of these data that the Kondo effect is responsible for the loss of intragranular superconductivity in a high-Tc superconductor with paramagnetic impurities. The experimental results are compared with those obtained from the theory of the Kondo effect for superconductors.
Acoustic cyclotron resonance and interaction of sound with Fermi-liquid cyclotron waves in metals
Authors: Zimbovskaya N. A.
Published: January 2025

It is shown that the interaction of ultrasound with short-wave longitudinal cyclotron waves can be manifested under the conditions of acoustic cyclotron resonance in very pure metal samples. This leads to a displacement of the principal resonance peak in the ultrasound absorption coefficient and to the emergence of additional peaks due to the excitation of Fermi-liquid modes of cyclotron waves. The possibilities of experimental observation of predicted phenomena are discussed.
On the effect of local anomalies of the Fermi surface curvature on quantum oscillatory phenomena in normal metals
Authors: Zimbovskaya N. A.
Published: January 2025

The influence of local curvature anomalies of extremal cross sections of the Fermi surface on the shape and amplitude of quantum oscillations of the density of states of the electron liquid in a metal is considered. It is shown that the vanishing of the curvature of an extremal cross section creates more favorable conditions for observing the features of low-temperature quantum oscillations in metals.
Exciton damping in a monatomic crystal
Authors: Grigorchuk N. I.
Published: January 2025

Analytic expressions for determining the attenuation of an exciton of an arbitrary radius in a monatomic crystal are obtained as functions of the lattice temperature and the exciton velocity by taking into account the exciton wave vector. The form of these dependences is analyzed in detail for the limiting cases of longitudinal modes of high and low (including T = 0) temperatures, slow and fast excitons, and large and small exciton radii. Some of the dependences coincide with the results obtained earlier. The calculations are made in the one-phonon approximation for a linear dependence of the acoustic phonon energy on the quasimomentum.
Observation of non-ohmic component of spontaneous conductivity fluctuations in YBa2Cu3O7–x thin films
Authors: Brodyanskii A. P. , Dmitrenko I. M. , Garbuz A. S. , Efremenko V. G. , Klimovskii Yu. A. , Fomin A. V. , Shustakova G. V. , Erenburg A. I.
Published: January 2025

Resistive and noise properties of thin single-crystal YBa2Cu3O7–x films with the c axis being parallel to the substrate plane have been studied. In the normal state as well as in the region of the superconducting transition we observed variations of the resistance fluctuation spectral density with current, which is direct evidence of structure elements with nonlinear current-voltage relationships present in high-Tc materials. On the basis of a comparison of data for c‖ and c⊥ films, certain inferences are made about the microscopic origin of the structure elements, responsible for the current nonlinearities in the noise properties of HTSC.

This article was printed in the September 1994 issue of Low Temperature Physics. It is now reprinted with all the necessary changes and corrections.
Elastic characteristics and low-temperature anomalies of the acoustical properties of high-temperature superconductors (review)
Authors: Lubenets S. V. , Natsik V. D. , Fomenko L. S.
Published: January 2025

Experimental data are given on the stiffness constants and the velocities of longitudinal and transverse elastic waves in a broad class of single crystals and ceramics of metal-oxide compounds: La2CuO4, La2–xSrxCuO4, YBa2Cu3O7–δ, and Bi(Pb)–Sr–Ca–Cu–O. The elastic moduli of isotropic polycrystalline samples, calculated by averaging the elastic moduli of single crystals of the corresponding materials, are given together with the Debye temperatures calculated from existing empirical values of the sound velocities. Data on the low-temperature anomalies of the acoustical properties of high-Tc superconducting single crystals and ceramics are systematized and generalized, including: relaxation peaks of the absorption of elastic waves; hysteresis of the temperature dependence of the elastic moduli; anomalies of the elastic characteristics in the vicinity of the superconducting transition temperature. The first results obtained from research on the elastic properties of fullerene C60 are discussed.
On the nature of linear dependence of conductance on voltage in tunnel junctions formed by high-temperature superconductors above the critical temperature
Authors: Pashitskiĭ È. A.
Published: January 2025

It is shown that the linear dependence of conductance on voltage, which is typical of tunnel junctions formed by high-temperature superconductors, can be due to inelastic scattering of tunneling electrons not only by spin density fluctuations (paramagnons) in the system of spins with antiferromagnetic correlations, but also by low-frequency charge density fluctuations (acoustic plasmons) in the system of virtually localized “heavy” charge carriers in an anomalously narrow band with a high density of states near the Fermi level, or by phonons with a very low Debye acoustic component of the spectrum and a broad optical spectrum.
Effect of axial pressure on the magnetic susceptibility of the intermetallic compound CeAI2
Authors: Desnenko V. A. , Panfilov A. S. , Smirnov A. I.
Published: January 2025

A SQUID magnetometer-based technique is proposed for studying the effect of axial compression on the magnetic moment of solids in the pressure range 1–2 kbar in the temperature interval 4.2–300 K. The application of this method for measuring the magnetic susceptibility of a CeAl2 single crystal in the paramagnetic region reveals a strong effect of axial pressure and its considerable anisotropy for different orientations of the magnetic field relative to the mechanical stress.
Electron structure of titanium near the structural phase transition point
Authors: Zhalko-Titarenko A. V. , Evlashina M. L. , Perlov A. Ya. , Yavorskiĭ B. Yu.
Published: January 2025

The possibility of emergence of structural instability in the bcc and hcp phases of titanium during a topological transformation of the Fermi surface associated with a change in temperature is considered on the basis of an analysis of the electron structure and the Fermi surface. Possible mechanisms of interrelation between peculiarities in the electron structure and the instability of the crystal lattice relative to the structural transition are discussed.
Investigation of energy and charge states of Co ions in Hg1–xCoxSe
Authors: Prozorovskiĭ V. D. , Reshidova I. Yu. , Paranchich Yu. S.
Published: January 2025

The results of investigations of energy and charge states of Co ions in Hg1–xCoxSe, obtained by using the electron spin resonance and Shubnikov–de Haas oscillations at microwave frequencies, are presented. An analysis of these results reveals that Hg1–x CoxSe has two magnetic spin centers. One of them is characterized by the g-factor equal to 2.23 and is formed by Co2+ ions whose levels lie in the valence band, and the other is characterized by the g-factor equal to 2.02 and is formed by clusters whose levels lie (0.13±0.01) eV above the bottom of the conduction band.
Heat capacity of solid solutions of 3He in 4He
Authors: Antsygina T. N. , Slyusarev V. A. , Chishko K. A.
Published: January 2025

The additional low-temperature heat capacity of solid solutions of helium isotopes with a concentration of the order of a few percent 3He in a 4He matrix is calculated theoretically. The impurity contribution to the thermodynamics of the solution is assumed to be the result of phase separation of the solid solution and the formation of quasi-one-dimensional structures of the second phase of 3He atoms by their settling on lines of lattice dislocations or by the buildup of fractal structures. The excess heat capacity is in the form of a peak in the temperature interval 50−200 μK, whose position on the temperature axis essentially depends only on the depth of the potential well ε0 ≃ − 1 K created by a dislocation for an impurity atom, and whose height is determined primarily by the parameter ξ ≃ 10−6−10−3, which represents the fraction of matrix lattice sites that can be occupied by the one-dimensional phase. The interaction energy of impurities in the volume of the crystal V ≃0.1 K is found to have an insignificant influence on the shape and position of the peak of the impurity heat capacity. The theoretical results exhibit good agreement with published experimental data for a solution with x3 = 0.9% 3He for one and only one choice of fitting parameters: ξ = 0.0058; V = 0.13 K; ε0 = −0.92 K.
Nonequilibrium current fluctuations in superconductor– normal metal tunnel structures
Authors: Naĭdenov S. V. , Khlus V. A.
Published: January 2025

General expressions for the current and spectral density of current fluctuations in the low-frequency limit are derived on the basis of the formalism of the scattering problem for a normal metal–superconductor junction with an arbitrary barrier in the presence of a constant external potential difference. It is shown that the dynamical and fluctuation characteristics of the system can behave differently, depending on the kind of tunneling (nonresonance tunneling in an unstructured barrier or resonance tunneling in a barrier containing localized states). A current equation admitting the existence of negative differential resistance in a certain range of values of the scattering parameters is derived for a specific resonance tunneling model. An equation is also derived for the current noise, whose spectral density contains additional terms not encountered in nonresonance tunneling, owing to the presence of electron–hole interference processes of scattering by a localized state.
Low-frequency magnetic flux noise in high-T
c superconducting SQUIDs
Authors: Shnyrkov V. I. , Timofeev V. P. , Tsoĭ G. M. , Khlus V. A. , Demin A. V.
Published: January 2025

Low-frequency magnetic flux fluctuations in high-Tc superconducting films and SQUIDs are investigated. It is shown that 1/f noise in epitaxial high-Tc superconducting samples in weak magnetic fields is attributable to discrete Josephson fluctuators, each consisting of a superconducting loop closed by weak links. It is confirmed by numerical analysis that the presence of such fluctuators can account for several unusual phenomena encountered in electronic devices utilizing high-Tc superconductors. It is noted that a junction utilizing a bicrystal interface is superior from the standpoint of minimizing the given noise mechanism.
Onset of magnetic ordering in nuclear spin systems with dipole–dipole interaction in the presence of low-temperature NMR saturation
Authors: Buishvili L. L. , Giorgadze N. P. , Khomeriki R. R.
Published: January 2025

The energy conservation law is used to investigate the equilibrium state established in a rotating reference frame during NMR saturation in a nuclear spin system with dipole– dipole interaction. The equilibrium values of the spin temperature and the polarization of the nuclei are calculated. It is shown that for a sufficiently high initial polarization of the nuclei the nuclear spin system can be brought into a magnetically ordered state in a rotating frame by NMR saturation.
Zero sound and the quasiwave: separation in a magnetic field
Authors: Bezuglyĭ E. V. , Boĭchuk A. V. , Burma N. G. , Fil’ V. D.
Published: January 2025

The behavior of longitudinal and transverse electron sound in a weak transverse magnetic field is investigated theoretically and experimentally. It is shown theoretically that the effects of a magnetic field on the zero sound velocity and on the ballistic transport velocity are opposite in sign and exhibit significantly different dependences on the sample thickness, the driving frequency, and the relaxation time. This fact can be exploited to separate experimentally the Fermi liquid and ballistic contributions to the observed longitudinal electron sound signal. The observation of ballistic transport of an acoustic disturbance by a quasiwave in zero magnetic field is reported for the first time.
Dislocation mechanism of low-temperature acoustic relaxation in niobium
Authors: Pal’-Val’ P. P. , Natsik V. D. , Pal’-Val’ L. N.
Published: January 2025

The influence of the concentration of impurities, orientation, cooldown rate, and initial plastic deformation on acoustic relaxation in single-crystal and polycrystalline samples of normal and superconducting niobium is investigated in the temperature interval 2–12 K. On the basis of an analysis of existing experimental data, it is hypothesized for the first time that the microscopic mechanism of acoustic relaxation in niobium at helium temperatures is the thermally activated motion of screw dislocation jogs in the ⟨111⟩{011} slip system through Peierls potential barriers of the second kind. A relaxation theory is proposed, based on the model of resonance interaction of sound with chains of dislocation jogs formed on screw dislocations under the influence of thermoelastic stresses during rapid cooldown of the sample. A comparison of the results of the theory and experimental data are used to estimate the density of jogs and to find the height of the Peierls barriers of the second kind and the variation of the barrier height in the superconducting transition.
Anomalies of the temperature dependence of the magnetostriction of NiCl2
Authors: Kalita V. M. , Lozenko A. F. , Trotsenko P. A.
Published: January 2025

It is shown that the anomalies of the temperature dependence of the strains of the NiCl2 lattice in the paramagnetic temperature range (T>TN) can be described on the basis of the mechanism of biquadratic, non-Heisenberg, isotropic interactions of fourth order in the spin. These anomalies are attributable to spontaneous growth of the quadrupole magnetic moment.
Influence of a heavy neon impurity on quantum diffusion in solid hydrogen
Authors: Minchina I. Ya. , Bagatskiĭ M. I. , Manzheliĭ V. G. , Muromtsev P. I.
Published: January 2025

Quantum diffusion in solid hydrogen containing 0.02–0.06 mole % neon in the temperature interval 1–3 K is investigated by a calorimetric technique. A neon impurity in the indicated concentrations is observed to accelerate quantum diffusion in hydrogen. The magnitude of the effect diminishes as the temperature increases.
Theory of the interaction of delocalized charge carriers with magnetic excitations in high-temperature superconductors
Authors: Loktev V. M. , Stefanovich M. A.
Published: January 2025

The notion of the existence of magnetic topological solitons (vortices) in the cuprate layers of high-temperature superconductors is used to calculate the energies of the bound states of a charge carrier with a vortex (vortexon) and of two carriers with a vortex (bivortexon). The possible role of bivortexons in the high-temperature superconductivity problem is discussed.
Electron phase relaxation in disordered gold films irradiated with Ar ions
Authors: Belevtsev B. I. , Komnik Yu. F. , Belyaev E. Yu.
Published: January 2025

The temperature dependence of electron phase relaxation time τφ at various extents of disorder are determined (in the temperature range 0.5–50 K) from analysis of quantum corrections to magnetoconductivity of thin gold films, which are associated with the effect of weak electron localization. The crystal lattice disorder is enhanced by bombarding the films with Ar ions in vacuum. It is found that the rates of inelastic electron relaxation due to electron– phonon scattering are described by a dependence of the form τep−1=Ap(l)Tp, where the exponent p is equal to two for low-resistance films and increases slightly in the case of strong disorder. In the latter case, the value of Ap becomes a function of the mean free path l, indicating a decrease in the electron–phonon interaction rate. Such a behavior of τep in the case of disorder can be explained by a transition from “pure” to “dirty” limit, when the value of l is of the order of the wavelength of thermal phonons, and the value of p is lower than that predicted by the theory apparently in view of the two-dimensional nature of electron–phonon interaction in thin films.
Some aspects of thermodynamics of a metastable ordered phase
Authors: Zavadskiĭ È. A. , Sukharevskiĭ B. Ya.
Published: January 2025

The lability boundaries of ordered and disordered phases, which are realized during first-order phase transitions, are correctly described on the phase diagrams T,X(X=P,H, etc.) in the Landau theory for T > Tz. For T=Tz, the lability boundary of the ordered quasi-equilibrium phase lies along this line. It is proposed that such a strong change in the lability boundary for T=Tz is associated with the strong cooperative interaction forming the ordered state and determining the conservation of the reached degree of ordering during heating up to Tz. This is equivalent to the statement that the entropy of the ordered subsystem at T=Tz is independent of the extrinsic parameters P and H.
Temperature–electric domain in a bimetallic plate
Authors: Logvinov I. I. , Chiang Yu. N.
Published: January 2025

The conditions for exciting a temperature–electric domain in a pure normal metal in contact with another (“dirty”) metal, through which directed heat transfer to a thermostat at 4.2 K is realized, are investigated. The parameters of the bimetallic system ensure the obtaining of a “low-temperature” domain at a temperature much lower than the Debye temperature. The domain is excited by a quasi-stationary current with inductive coupling of the system with the current source. The current–voltage characteristics of discrete segments of the system are measured over its whole length in the bistable state. The thermoelectric velocity of the domain is estimated, and the conditions for domain pinning at an extended inhomogeneity associated with the nonideal nature of the sample cross section are analyzed.
Magnetic flux dynamics in granular HTS materials
Authors: Nemoshkalenko V. V. , Kordyuk A. A.
Published: January 2025

The frequency dependences of energy losses in Y-123 and Bi(Pb)-2223 HTS materials are investigated at 77 K in longitudinal and transverse varying magnetic fields by studying various modes of forced vibrations of a permanent magnet suspended above the HTS sample. It is shown that the magnetization hysteresis for a granular HTS sample is determined by magnetic flux pinning at the surface of superconducting granules, and energy losses in the Y-sample at frequencies ∼ 10 Hz and the varying magnetic field amplitudes 1–10 Oe are due to thermally activated flow in superconducting granules.
Electron spin resonance and magnetic susceptibility of Hg1−xCrxSe solid solutions with 0.00112⩽x⩽ 0.07
Authors: Prozorovskiĭ V. D. , Reshidova I. Yu. , Puzynya A. I. , Paranchich Yu. S.
Published: January 2025

The results of experimental investigations of electron spin resonance and magnetic susceptibility in a semimagnetic semiconductor Hg1−x CrxSe(0.00112⩽x⩽0.07) are considered. These results indicate the presence of an asymmetric crystal lattice distortion caused by a change in temperature and a transition of Hg1−xCrxSe to the spin-glass state, which is induced by this distortion. The temperatures corresponding to the onset of the change in the lattice symmetry and the phase transition increase with the index x of the solid solution.
Nuclear magnetic resonance in a thin film of an easy-plane antiferromagnet
Authors: Tarasenko S. V.
Published: January 2025

The conditions required for the formation of new types of propagating nuclear spin–wave excitations associated with the symmetry of magnetoelastic and elastic interactions are analyzed both for an isolated magnetic film and for a magnetic film with a nonmagnetic coating.
New acoustic-type vibrational mode in Nd(Pr)2CuO4 single crystals
Authors: Fil’ D. V. , Kolobov I. G. , Fil’ V. D. , Barilo S. N. , Zhigunov D. I.
Published: January 2025

Velocities of sound along main crystallographic directions of Nd(Pr)2CuO4 single crystals and their angular dependences in (100) and (110)-type planes have been measured. The anomalies observed in angular dependences are interpreted as the result of interaction of elastic vibrations with an additional plane mode of the acoustic type. According to this interpretation, the spectrum of the additional mode is two-dimensional, and its origin is associated with electron degrees of freedom in CuO2 planes. A phenomenological model is proposed for describing the spectra of acoustic modes in the systems under investigation. A possible microscopic scenario of the formation of the additional mode is analyzed on the basis of the anyon model of HTS. The values of the Debye temperature calculated in the phenomenological model are in accord with calorimetric data. The values of components of the elastic moduli tensor are given.
Peculiarities of low-temperature spectroscopy of dopant centers with a multiwell adiabatic potential
Authors: Malyukin Yu. V. , Pogrebnyak N. L. , Seminozhenko V. P.
Published: January 2025

The results of low-temperature spectroscopy for two different dopant centers characterized by a multiwell adiabatic potential are presented. It is shown that two-level systems associated with a multiwell adiabatic potential can be manifested in relaxation processes if they are thermally activated in the temperature range lower than the Debye temperature.
Halide perovskites, a game changer for future medical imaging technology
Authors: Li Feng
Published: January 2025

The accurate detection of x-rays enables broad applications in various fields, including medical radiography, safety and security screening, and nondestructive inspection. Medical imaging procedures require the x-ray detection devices operating with low doses and high efficiency to reduce radiation health risks, as well as expect the flexible or wearable ones that offer more comfortable and accurate diagnosis experiences. Recently, halide perovskites have shown promising potential in high-performance, cost-effective x-ray detection owing to their attractive features, such as strong x-ray absorption, high-mobility–lifetime product, tunable bandgap, fast response, as well as low-cost raw materials, facile processing, and excellent flexibility. In this review, we comprehensively summarize the recent advances in halide perovskite x-ray detectors and imaging, focusing on their application potential in medical imaging technology. We highlight the recent demonstrations and optimizations of halide perovskite x-ray detectors and imaging and their application in medical radiography. Finally, we conclude by pointing out the challenges of perovskite x-ray detection devices for the clinical practical applications and by sharing our perspectives on the potential solutions for driving the field forward.
Harnessing ferro-valleytricity in pentalayer rhombohedral graphene for memory and compute
Authors: Islam Md Mazharul , Alam Shamiul , Udoy Md Rahatul Islam , Hossain Md Shafayat , Hamilton Kathleen E , Aziz Ahmedullah
Published: January 2025

Two-dimensional materials with multiple degrees of freedom, including spin, valleys, and orbitals, open up an exciting avenue for engineering multifunctional devices. Beyond spintronics, these degrees of freedom can lead to novel quantum effects such as valley-dependent Hall effects and orbital magnetism, which could revolutionize next-generation electronics. However, achieving independent control over valley polarization and orbital magnetism has been a challenge due to the need for large electric fields. A recent breakthrough involving pentalayer rhombohedral graphene has demonstrated the ability to individually manipulate anomalous Hall signals and orbital magnetic hysteresis, forming what is known as a valley-magnetic quartet. Here, we leverage the electrically tunable ferro-valleytricity of pentalayer rhombohedral graphene to develop nonvolatile memory and in-memory computation applications. We propose an architecture for a dense, scalable, and selector-less nonvolatile memory array that harnesses the electrically tunable ferro-valleytricity. In our designed array architecture, nondestructive read and write operations are conducted by sensing the valley state through two different pairs of terminals, allowing for independent optimization of read/write peripheral circuits. The power consumption of our PRG-based array is remarkably low, with only ∼6 nW required per write operation and ∼2.3 nW per read operation per cell. This consumption is orders of magnitude lower than that of the majority of state-of-the-art cryogenic memories. Additionally, we engineer in-memory computation by implementing majority logic operations within our proposed nonvolatile memory array without modifying the peripheral circuitry. Our framework presents a promising pathway toward achieving ultra-dense cryogenic memory and in-memory computation capabilities.
Small polarons mediated near-room-temperature metal–insulator transition in vanadium dioxide and their hopping dynamics
Authors: Liu Xiongfang , Yang Tong , Chen Shanquan , Wu Jing , Tang Chi Sin , Ning Yuanjie , Chen Zuhuang , Dai Liang , Sun Mengxia , Chen Mingyao , Han Kun , Zhou Difan , Zeng Shengwei , Sun Shuo , Li Sensen , Yang Ming , Breese Mark B. H. , Cai Chuanbing , Venkatesan Thirumalai , Wee Andrew T. S. , Yin Xinmao
Published: January 2025

Researchers pursuing advanced photoelectric devices have discovered near room-temperature metal–insulator transitions (MIT) in nonvolatile VO2. Despite theoretical investigations suggesting that polaron dynamics mediate the MIT, direct experimental evidence remains scarce. In this study, we present direct evidence of the polaron state in insulating VO2 through high-resolution spectroscopic ellipsometry measurements and first-principles calculations. We illustrate the complementary role of polaron dynamics in facilitating Peierls and Mott transitions, thereby contributing to the MIT processes. Furthermore, our observations and characterizations of conventional metallic and correlated plasmons in the respective phases of the VO2 film offer valuable insight into their electron structures. This investigation enhances comprehension of the MIT mechanism in correlated systems and underscores the roles of polarons, lattice distortions, and electron correlations in facilitating phase transition processes in strongly correlated systems. Additionally, the detailed detection of small polarons and plasmons serves as inspiration for the development of new device functionalities.
Fine structures in interlaced magnetic flux ropes via Hall-MHD simulations
Authors: Jia Ying-Dong , Lai Hairong , Wei Hanying , Qi Yi , Russell C. T. , Ge Yasong , Zhang Tielong
Published: January 2025

Magnetic flux ropes are a fundamental component in both space and laboratory plasmas. We present a Hall-MHD simulation exploring the interaction between two isolated magnetic flux ropes under mesoscale solar wind conditions. The interaction interface is resolved with a resolution approaching the kinetic scale, to reveal unprecedented details of this process. As we replicate previous findings that such interactions can lead to the formation of two new ropes, we also find that magnetic reconnection occurs in multiple locations inside the central current sheet, leading to transient small flux ropes, which is qualitatively consistent with previous magnetospheric multiscale observations. Consequently, each field line undergoes multiple reconnections that alter its connectivity before it exits the current sheet. Later, each flux rope divides into two branches: the reconnected flux moving away from the current sheet to form the transition regions of the new ropes and the remnant flux sustaining the current sheet. For each magnetic flux rope (MFR), the core field reconnects after most surface fields are reconnected so that the reconnecting MFRs maintain a relatively symmetric shape. These results in unprecedented detail highlight the complex internal dynamics and call for further observational and theoretical studies.