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The presence of Rashba-like surface states (RSS) in the electronic structure of topological insulators (TIs) has been a longstanding topic of interest due to their significant impact on electronic and spin structures. In this study, we investigate the interaction between topological and Rashba-like surface states (TSS and RSS) in Mn$_{1-x}$Sn$_x$Bi$_2$Te$_4$ systems using density functional theory (DFT) calculations and high-resolution ARPES. Our findings reveal that increasing Sn concentration shifts RSS downward in energy, enhancing their influence on the electronic structure near the Fermi level. ARPES validates these predictions, capturing the evolution of RSS and their hybridization with TSS. Orbital analysis shows RSS are localized within the first three Te-Bi-Te trilayers, dominated by Bi $p$-orbitals, with evidence of the orbital Rashba effect enhancing spin-momentum locking. At higher Sn concentrations, RSS penetrate deeper into the crystal, driven by Sn $p$-orbital contributions. These results position Mn$_{1-x}$Sn$_x$Bi$_2$Te$_4$ as a tunable platform for tailoring electronic properties in spintronic and quantum technologies.

A stochastic model for a super-position of uncorrelated pulses with a random distribution of and correlations between amplitudes and velocities is analyzed. The pulses are assumed to move radially with fixed shape and amplitudes decreasing exponentially in time due to linear damping. The pulse velocities are taken to be time-dependent with a power law dependence on the instantaneous amplitudes, as suggested by blob velocity scaling theories. In accordance with experimental measurements, the pulse function is assumed to be exponential and the amplitudes are taken to be exponentially distributed. As a consequence of linear damping and time-dependent velocities, it is demonstrated that the pulses stagnate during their radial motion. This makes the average pulse waiting time increase radially outwards in the scrape-off layer of magnetically confined plasmas. In the case that pulse velocities are proportional to their amplitudes, the mean value of the process decreases exponentially with radial coordinate, similar to the case when all pulses have the same, time-independent velocity. The profile e-folding length is then given by the product of the average pulse velocity and the parallel transit time. Moreover, both the average pulse amplitude and the average velocity are the same at all radial positions due to stagnation of slow and small-amplitude pulses. In general, an increasing average pulse velocity results in a flattened radial profile of the mean value of the process as well as a higher relative fluctuation level, strongly enhancing plasma-surface interactions.

RED-100 is a two-phase emission detector with an active volume containing 126~kg of liquid xenon. The detector was exposed to the antineutrino flux of about $1.4 \cdot 10^{13}~$cm$^{-2}$s$^{-1}$ at a distance of 19~m from the 3.1~GW Kalinin Nuclear Power Plant (KNPP) reactor core. The comparison of data from 331~kg$\cdot$days with the reactor on and 106~kg$\cdot$days with the reactor off shows no statistically significant excess and allows to put constraints on coherent elastic interactions of antineutrinos with xenon nuclei.

The spin-resolved dispersion dependencies for the topological insulator Mn$_{1-x}$Ge$_x$Bi$_2$Te$_4$ in the $\bar{\rm K}\bar{\Gamma}\bar{\rm K}'$ path of the Brillouin zone were studied by spin- and angle-resolved photoemission spectroscopy using laser radiation (Laser Spin-ARPES) with variation of the concentration of substitutional Ge atoms (x from 0.1 to 0.8) for in-plane ($s_x$) and out-of-plane ($s_z$) spin orientation. The formation of Rashba-like states is shown, which shift to lower energies with increasing Ge concentration. In the region of Ge concentrations from 50% to 75%, the contribution of these states to the formed spin-dependent dispersions becomes predominant. A pronounced in-plane ($s_y$) spin polarization, asymmetric for opposite $\pm k_\parallel$ directions, is revealed for the Dirac cone states, while the Rashba-like states exhibit a pronounced asymmetry in both in-plane ($s_y$) and out-of-plane ($s_z$) spin polarizations. Theoretical calculations confirmed the asymmetric polarization of the Rashba-like states formed in the $\bar{\rm K}\bar{\Gamma}\bar{\rm K}'$ path of the BZ, simultaneously for in-plane and out-of-plane spin orientation. Constant energy maps for Rashba-like states show a pronounced $s_z$ spin component along the $\bar{\Gamma}\bar{\rm K}$ direction, with a sign change as the contour crosses the $\bar{\Gamma}\bar{\rm M}$ direction. The observed spin polarization can influence the development of spin devices based on magnetic topological insulators.

This study investigates methods for controlling the physical properties of the intrinsic magnetic topological insulator MnBi$_2$Te$_4$ (MBT) by substituting Mn with Pb in Mn$_{1-x}$Pb$_x$Bi$_2$Te$_4$ (MPBT) solid solutions. This substitution enables tunable magnetic and electronic properties. Using various angle-resolved photoemission spectroscopy (ARPES) techniques, including spin-resolved and circular dichroism (CD) measurements, we analyzed the evolution of the electronic structure across different Pb concentrations, with a focus on topological phase transitions (TPT) near x = 50 %. Key indicators of TPT include the presence or absence of topological surface states (TSS) and bulk band gap closure. The results show a gradual decrease of the bulk band gap in the electronic structure of MPBT up to x = 40 %, where it nearly vanishes, followed by a constant gap value between 40 - 60 %, and its reopening above 80 %, which is accompanied by a transition of the electronic structure of MPBT to a PbBi$_2$Te$_4$-like electronic structure. TSS were observed at x less than 30 % and greater than 80 %, as confirmed by CD and spin-resolved ARPES data, but were absent near x = 55 %, suggesting a distinct topological phase - possibly semi-metallic or a trivial insulator with a narrow gap phase. These findings demonstrate the tunability of the electronic structure of MPBT, making it a promising candidate for topological and spintronic applications.

This study investigates a novel method for estimating two-dimensional velocities using coarse-grained imaging data, which is particularly relevant for applications in plasma diagnostics. The method utilizes measurements from three non-collinear points and is derived from a stochastic model that describes the propagation of uncorrelated pulses through two-dimensional space. This model builds upon a well-studied one-dimensional model used to analyze turbulence in the scrape-off layer of magnetically confined plasmas. We demonstrate that the method provides exact time delay estimates when applied to a superposition of Gaussian structures and remains accurate for various other pulse functions. Through extensive numerical simulations, we evaluate the method's performance under different conditions, including variations in signal duration, pulse overlap, spatial and temporal resolution, and the presence of additive noise. Additionally, we investigate the impact of temporal pulse evolution due to linear damping and explore the so-called barberpole effect, which occurs with elongated and tilted structures. Our analysis reveals that the three-point method effectively addresses the limitations encountered with two-point techniques, particularly at coarse spatial resolutions. Although the method is susceptible to the barberpole effect, we analytically demonstrate that this effect does not occur when the elongated structures propagate parallel to one of their axes, and we establish bounds for the associated errors. Overall, our findings provide a comprehensive and robust framework for accurate two-dimensional velocity estimation, enhancing the capabilities of fusion plasma diagnostics and potentially benefiting other fields requiring precise motion analysis.

A set of polar rod-shaped liquid crystalline molecules with large dipole moments (mu > 10.4-14.8 D), their molecular structures based on the ferroelectric nematic prototype DIO, are designed, synthesized, and investigated. When the penultimate fluoro-phenyl ring is replaced by phenylpyrimidine moiety, the molecular dipole moment increases from 9.4 D for DIO to 10.4 D for the new molecule and when the terminal fluoro-group is additionally replaced by the nitrile group, the dipole moment rises to 14.8 D. Such a replacement enhances not only the net dipole moment of the molecule, but it also reduces the steric hindrance to rotations of the moieties within the molecule. The superparaelectric nematic (N) and smectic A (SmA) phases of these compounds are found to exhibit colossal dielectric permittivity, obtained both from dielectric spectroscopy, and capacitance measurements using a simple capacitor divider circuit. The electric polarization is measured vs. the field (E). However, no hysteresis in P vs. E is found in the nematic and smectic A phases. The colossal dielectric permittivity persists over the entire fluidic range. The experimental results lead us to conclude that these materials belong to the class of superparaelectrics (SPE) rather than to ferroelectrics due to the absence hysteresis and linear P vs E dependence. The synthesized organic materials are the first fluids for which superparaelectricity is discovered and furthermore these show great potential for the applications in supercapacitors used in storing energy., Comment: 24 pages, 7 figures, 1 table. Submited to JMC C

Here, by applying a comprehensive approach including magnetic, transport measurements, ARPES band structure measurements, DFT calculations, and analytical theory consideration, we unveil the puzzling origin of the negative isotropic magnetoresistance in the highly anisotropic semimetals, particularly, Eu$_2$Sn$_2$As$_2$ with AFM ordering of Eu atoms. The isotropic magnetoresistance developing along with the magnetization changes up to the complete spin polarization field was reported previously in several experimental studies, though its theoretical explanation was missing up to date. Recently, we proposed a novel theoretical mechanism to describe the observed magnetoresistance in layered AFM compounds by exchange splitting of the electron energy levels and by confining the electron wave functions with different spin projection in the vicinity of the respective magnetic layer. In this paper, we present more detailed experimental studies of the negative magnetoresistance with several samples of EuSn$_2$As$_2$ in order to identify its sample-independent features including temperature dependence. We also substantiate the proposed theory by comparing it with magnetotransport data, with ARPES measurements of the energy band structure, and DFT energy spectrum calculations., Comment: 24 pages, 20 figures (including SM)

Networks of nonlocally coupled leaky Integrate-and-Fire neurons exhibit a variety of complex collective behaviors, such as partial synchronization, frequency or amplitude chimeras, solitary states and bump states. In particular, the bump states consist of one or many regions of asynchronous elements within a sea of quiescent subthreshold elements. The asynchronous domains (also called bumps) travel in the network in a direction predetermined by the initial conditions. In the present study we investigate the occurrence of bump states in networks of leaky Integrate-and-Fire neurons in two-dimensions using nonlocal toroidal connectivity and we explore possible mechanisms for stabilizing the moving asynchronous domains. Our findings indicate that I) incorporating a refractory period can effectively anchor the position of these domains in the network, and II) the switching off of some randomly preselected nodes (i.e., making them permanently idle/inactive) can likewise contribute to stabilizing the positions of the asynchronous domains. In particular, in case II for large values of the coupling strength and a large percentage of idle elements, all nodes acquire different fixed (frozen) values in the subthreshold region and oscillations cease throughout the network due to self-organization. For the special case of stationary bump states, we propose an analytical approach to predict their properties. This approach is based on the self-consistency argument and is valid for infinitely large networks. Case I is of particular biomedical interest in view of the importance of refractoriness for biological neurons, while case II can be biomedically relevant when designing therapeutic methods for stabilizing moving signals in the brain.

Long-range correlations manifested as power spectral density scaling $1/f^\beta$ for frequency $f$ and a range of exponents $\beta$ are investigated for a superposition of uncorrelated pulses with distributed durations $\tau$. Closed-form expressions for the frequency power spectral density are derived for a one-sided exponential pulse function and several variants of bounded and unbounded power-law distributions of pulse durations ${P_\tau(\tau)\sim1/\tau^\alpha}$ with abrupt and smooth cutoffs. The asymptotic scaling relation $\beta=3-\alpha$ is demonstrated for $1<\alpha<3$ in the limit of an infinitely broad distribution $P_\tau(\tau)$. Logarithmic corrections to the frequency scaling are exposed at the boundaries of the long-range dependence regime, $\beta=0$ and $\beta=2$. Analytically demonstrated finite-size effects associated with distribution truncations are shown to reduce the frequency ranges of scale invariance by several decades. The regimes of validity of the $\beta=3-\alpha$ relation are clarified., Comment: 17 pages, 6 figures, 2 tables. Follow-up of this paper: https://link.aps.org/doi/10.1103/PhysRevResearch.5.L022066 . [v3]: major revision, sections reorganized, plots of empirical power spectral densities added

An analog of the optical polarizer/analyzer for electrons, a spin filter based on freestanding ferromagnetic (FM) nanomembrane covering the entrance of the microchannel plate (MCP) was applied for efficient spin filtering and electron amplification in the 2D field of view. To study the spin dependent transmission, we constructed a spin-triode device (spintron), which consists of a compact proximity focused vacuum tube with the Na2KSb spin-polarized electron source, the FM-MCP and phosphor screen placed to run parallel to each other. Here, we demonstrate the fabrication of FM nanomembranes consisting of a Co/Pt superlattice deposited on a freestanding 3 nm SiO2 layer with a total thickness of 10 nm. The FM-MCP has 10e6 channels with a single-channel Sherman function S=0.6 and a transmission of 1.5x10e-3 in the low electron energy range. The FM-MCP-based device provides a compact optical method for measuring the spin polarization of free electron beams in the imaging mode and is well suited for photoemission spectroscopy and microscopy methods., Comment: 11 pages, 4 figures

We investigate a trapped mixture of Bose-Einstein condensates consisting of a multiple number of P species using an exactly-solvable many-body model, the $P$-species harmonic-interaction model. The solution is facilitated by utilizing a double set of Jacoby coordinates. A scheme to integrate the all-particle density matrix is derived and implemented. Of particular interest is the infinite-particle-number limit, which is obtained when the numbers of bosons are taken to infinity while keeping the interaction parameters fixed. We first prove that at the infinite-particle-number limit {\it all} the species are $100\%$ condensed. The mean-field solution of the $P$-species mixture is also obtained analytically, and is used to show that the energy per particle and densities per particle computed at the many-body level of theory boil down to their mean-field counterparts. Despite these, correlations in the mixture exist at the infinite-particle-number limit. To this end, we obtain closed-form expressions for the correlation energy and the depletion of the species at the infinite-particle-number limit. The depletion and the correlation energy per species are shown to critically depend on the number of species. Of separate interest is the entanglement between one species of bosons and the other $P-1$ species. Interestingly, there is an optimal number of species, here $P=3$, where the entanglement is maximal. Importantly, the manifestation of this interspecies entanglement in an observable is possible. It is the position-momentum uncertainty product of one species in the presence of the other $P-1$ species which is derived and demonstrated to correlate with the interspecies entanglement. All in all, we show and explain how correlations at the infinite-particle-number limit of a trapped multiple-species bosonic mixture depend on the interactions, and how they evolve with the number of species., Comment: 43+\eps pages, 5 figures

Propagation of ultrarelativistically intense laser pulse in a self-trapping mode in a near critical density plasma makes it possible to produce electron bunches of extreme parameters appropriate for different state of art applications. Based on the 3D PIC simulations, it has been demonstrated how the best efficiency of electron acceleration in terms of the total charge of high-energy electrons and laser-to-electrons conversion rate can be achieved. For given laser pulse energy the universal way is a proper matching of laser hot spot size and electron plasma density to the laser pulse duration. The recommendation to achieve the highest yield of high-energy electrons is to compress laser pulse as much as possible. As example, compression of the few tens fs pulse to the 10 fs pulse leads to generation of the high-energy electron bunch with the highest total charge to exhibit conversion efficiency exceeding 50% for the Joule-level laser pulse energies.

The ESO public survey VISTA Variables in the V\'ia L\'actea (VVV) surveyed the inner Galactic bulge and the adjacent southern Galactic disk from $2009-2015$. Upon its conclusion, the complementary VVV eXtended (VVVX) survey has expanded both the temporal as well as spatial coverage of the original VVV area, widening it from $562$ to $1700$ sq. deg., as well as providing additional epochs in $JHK_{\rm s}$ filters from $2016-2023$. With the completion of VVVX observations during the first semester of 2023, we present here the observing strategy, a description of data quality and access, and the legacy of VVVX. VVVX took $\sim 2000$ hours, covering about 4% of the sky in the bulge and southern disk. VVVX covered most of the gaps left between the VVV and the VISTA Hemisphere Survey (VHS) areas and extended the VVV time baseline in the obscured regions affected by high extinction and hence hidden from optical observations. VVVX provides a deep $JHK_{\rm s}$ catalogue of $\gtrsim 1.5\times10^9$ point sources, as well as a $K_{\rm s}$ band catalogue of $\sim 10^7$ variable sources. Within the existing VVV area, we produced a $5D$ map of the surveyed region by combining positions, distances, and proper motions of well-understood distance indicators such as red clump stars, RR Lyrae, and Cepheid variables. In March 2023 we successfully finished the VVVX survey observations that started in 2016, an accomplishment for ESO Paranal Observatory upon 4200 hours of observations for VVV+VVVX. The VVV+VVVX catalogues complement those from the Gaia mission at low Galactic latitudes and provide spectroscopic targets for the forthcoming ESO high-multiplex spectrographs MOONS and 4MOST., Comment: 17 pages, 11 figures (+ appendix). Accepted for publication in Astronomy and Astrophysics in section 14: Catalogs and data

Using angle-resolved photoemission spectroscopy (ARPES) and density functional theory (DFT), an experimental and theoretical study of changes in the electronic structure (dispersion dependencies) and corresponding modification of the energy band gap at the Dirac point (DP) for topological insulator (TI) $\mathrm{Mn}_{1-x} \mathrm{Ge}_x \mathrm{Bi}_2 \mathrm{Te}_4$ have been carried out with gradual replacement of magnetic Mn atoms by non-magnetic Ge atoms when concentration of the latter was varied from 10$\%$ to 75$\%$. It was shown that when Ge concentration increases then the bulk band gap decreases and reaches zero plateau in the concentration range of 45$\%$-60$\%$ while non-topological surface states (TSS) are present and exhibit an energy splitting of 100 and 70 meV in different types of measurements. It was also shown that TSS disappear from the measured band dispersions at a Ge concentration of about 40$\%$. DFT calculations of $\mathrm{Mn}_{1-x} \mathrm{Ge}_x \mathrm{Bi}_2 \mathrm{Te}_4$ band structure were carried out to identify the nature of observed band dispersion features and to analyze a possibility of magnetic Weyl semimetal state formation in this system. These calculations were performed for both antiferromagnetic (AFM) and ferromagnetic (FM) ordering types while the spin-orbit coupling (SOC) strength was varied or a strain (compression or tension) along the $c$-axis was applied. Calculations show that two different series of topological phase transitions (TPTs) may be implemented in this system depending on the magnetic ordering. At AFM ordering transition between TI and trivial insulator phase goes through the Dirac semimetal state, whereas for FM phase such route admits three intermediate states instead of one (TI - Dirac semimetal - Weyl semimetal - Dirac semimetal - trivial insulator).

A quantitative theoretical study of the dissociative recombination of SH$^+$ with electrons has been carried out. Multireference, configuration interaction calculations were used to determine accurate potential energy curves for SH$^+$ and SH. The block diagonalization method was used to disentangle strongly interacting SH valence and Rydberg states and to construct a diabatic Hamiltonian whose diagonal matrix elements provide the diabatic potential energy curves. The off-diagonal elements are related to the electronic valence-Rydberg couplings. Cross sections and rate coefficients for the dissociative recombination reaction were calculated with a step-wise version of the multichannel quantum defect theory, using the molecular data provided by the block diagonalization method. The calculated rates are compared with the most recent measurements performed on the TSR ion storage ring in Heidelberg, Germany., Comment: 17 pages, 15 figures, 4 tables

Shubnikov-de Haas (SdH) oscillations and magneto-intersubband oscillations of magnetoresistance of structures with single HgTe quantum wells with a width of (10-18) nm have been experimentally studied. The spectrum of the conduction band in these structures is split by the spin-orbit interaction. This leads to beats of the SdH oscillations and the appearance of low-frequency magneto-intersubband oscillations. The mutual position of the antinodes of the SdH oscillations and the maxima of the magneto-interband oscillations is unusual -- in low magnetic fields it is directly opposite to the predictions of the theory. Measurements in high magnetic fields, in which the relative amplitude of the SdH oscillations becomes greater than 0.2-0.3, show a change in the relative position of the antinodes of the SdH oscillations and the maxima of low-frequency oscillations. Numerical calculations and additional measurements at different temperatures show that the observed effects are due to oscillations of the Fermi level in the magnetic field., Comment: 7 two-column pages, 10 figures

We introduce pentacene-doped naphthalene as a material for diamagnetic levitation, offering compelling applications in matter-wave interferometry and nuclear magnetic resonance. Pentacene-doped naphthalene offers remarkable polarizability of its nuclear spin ensemble, achieving polarization rates exceeding 80 % at cryogenic temperatures with polarization lifetimes extending weeks. We design a multi-spin Stern-Gerlach-type interferometry protocol which, thanks to the homogeneous spin distribution and the absence of a preferential nuclear-spin quantization axis, avoids many of the limitations associated with materials hosting electronic spin defects, such as nanodiamonds containing NV centers. We assess the potential of our interferometer to enhance existing bounds on the free parameters of objective collapse models. Beyond matter-wave interferometry, we analyze the prospects for implementing magic angle spinning at frequencies surpassing the current standard in NMR, capitalizing on the exceptional rotational capabilities offered by levitation. Additionally, we outline a novel protocol for measuring spin ensemble polarization via the position of the nanoparticle and conduct an analysis of dominant noise sources, benchmarking the required isolation levels for various applications., Comment: 27 pages, 10 figures