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Boron-based compounds have triggered substantial attention due to their multifunctional properties, incorporating excellent hardness and superconductivity. While tetragonal metal borides LiB4 and NaB4 with BaAl4-type structure and striking clathrate boron motif have been induced under compression, there is still a lack of deep understanding of their potential properties at ambient pressure. We herein conduct a comprehensive study on I4/mmm-structured LiB4 and NaB4 under ambient pressure via first-principles calculations. Remarkably, both LiB4 and NaB4 are found to possess high Vickers hardness of 39 GPa, which is ascribed to the robust boron framework with strong covalency. Furthermore, their high hardness values together with distinguished stability make them highly potential superhard materials. Meanwhile, electron–phonon coupling analysis reveals that both LiB4 and NaB4 are conventional phonon-mediated superconductors, with critical temperatures of 6 and 8 K at 1 atmosphere pressure (atm), respectively, mainly arising from the coupling of B 2p electronic states and the low-frequency phonon modes associated with Li-, Na-, and B-derived vibrations. This work provides valuable insights into the mechanical and superconducting behaviors of metal borides and will boost further studies of emergent borides with multiple functionalities. [ABSTRACT FROM AUTHOR]

With the motivation of searching for new superconductors with better hardness in the Th–B system, we have performed ab initio evolutionary searches for all the stable compounds in this binary system in the pressure range of 0–200 GPa. From our enthalpy of formation calculations, it is found that only ThB4 (Space group No. P4/mbm), ThB6 (Space group No. P m 3 ¯ m), and ThB12 (Space group No. F m 3 ¯ m) compositions are preferred at zero pressure, in accordance with the experimental reports. Under pressure, our calculations predict the thermodynamically stable compositions, ThB (Space group No. R 3 ¯ m), Th3B4 (Space group No. R 3 ¯ m), ThB2 (Space group No. Amm2), and ThB8 (Space group No. R 3 ¯ m) at 54, 19, 35, and 51 GPa, respectively. Furthermore, although the thermodynamical stability of these compounds is predicted to be at high pressures, the possibility of occurrence at 0 GPa due to metastability still exists. The detailed calculations and analysis of the electronic structure and mechanical and thermal properties have been carried out on these materials using the ab initio tool. The P4/mbm phase of ThB4 and the F m 3 ¯ m phase of ThB12 exhibit high hardness of 30.5 and 35.2 GPa under ambient conditions, which is comparable the hard material, B4C. On the other hand, among all the thorium borides, ThB2 shows a high electron–phonon coupling constant of 0.804 and is predicted to have Tc around 12.72 K. In addition, it has been found that the predicted high-pressure compositions, Th3B4 and ThB, display superconductive behavior under pressure. Additionally, various thermophysical quantities such as lattice thermal conductivity, bulk modulus, thermal expansion coefficient, specific heat capacity, and Gibbs free energy under ambient conditions have been determined from these calculations. [ABSTRACT FROM AUTHOR]

The conventional theory of superconductivity holds that Cooper pairs form due to electron–phonon coupling; however, this description may not be adequate to describe certain unconventional superconductors such as cuprates and iron chalcogenides. In these unconventional superconductors, it has been proposed that spin fluctuations may be responsible for the formation of Cooper pairs. In this study, we explore spin interactions in the transition metal, dichalcogenide niobium disulfide, induced through proximity effects by fabricating antiferromagnet/NbS2 heterostructures. We tested three different 2D antiferromagnetic materials, each with different spin textures: anganese phosphorus trisulfide, manganese phosphorus triselenide, and chromium trichloride. Our results showed a substantial reduction in the critical temperature in the case of NbS2/MnPSe3. We hypothesize that this could be due to spin fluctuations in MnPSe3 inducing proximity effects in NbS2. [ABSTRACT FROM AUTHOR]

Nanostructure control is of fundamental and technological importance because various properties such as vortex pinning in superconductors are determined by the nanostructure. While the nanostructure in superconducting oxides is well controlled, the nanostructure control of iron-based superconductors is required. The nanostructure has not yet been well controlled even in Fe(Te,Se) with the simplest structure among Fe-based superconductors because the anion may be non-stoichiometric and anionic substitution is possible. In this study, we observed the compositional inhomogeneity originating from phase separation in Fe(Te,Se) films, which were prepared by pulsed laser deposition. The films deposited at lower temperature do not show nanoscale compositional inhomogeneity. On the other hand, the high-temperature deposited films contain an inhomogeneous anion distribution with the size of ∼8 nm due to phase separation. The spacing of the compositional inhomogeneity is ∼16 nm. This structure obtained by phase separation is expected to be an effective pinning center in high magnetic fields after further optimization. Thus, the method of nanostructure control other than nanocomposite formation in oxides is demonstrated for Fe(Te,Se). [ABSTRACT FROM AUTHOR]

Summary: Non‐orthogonal multiple access (NOMA) has proven to be a very effective multiple access scheme to be employed in visible light communication (VLC) systems. NOMA scheme is capable of enhancing the spectral efficiency, sum rate performance, and various other performance parameters in VLC systems as compared to traditional orthogonal multiple access schemes. However, it is not practical to apply the concept of NOMA to all the users jointly. Therefore, the concept of user pairing has been introduced in literature to implement NOMA effectively so as to reduce the decoding order of successive interference cancellation (SIC) mechanism and complexity. In this paper, we have proposed a user pairing scheme based on clustering for downlink 3D NOMA‐based VLC systems. In this user pairing scheme, clustering is performed prior user pairing. The number of clusters are selected using K‐means algorithm and Elbow method, and the user allocation in a particular cluster is validated using artificial bee colony (ABC) optimization. In order to achieve high throughput, inter‐cluster user pairing is performed by forming pairs of two or three users with maximum channel gain difference in between them. The simulation results show that, for given values of signal‐to‐noise ratio (SNR), the proposed user pairing scheme offers higher average user data rates (AUDRs) as compared to the existing user pairing schemes for downlink NOMA‐based VLC systems. The energy efficiency (EE) and the bit error rate (BER) performance of the proposed user pairing scheme have also been studied. [ABSTRACT FROM AUTHOR]

High-entropy alloy (HEA) superconductors have attracted significant attention due to their exceptional low-temperature mechanical and superconducting properties. We report the synthesis and thorough characterization of an equiatomic HEA superconductor with the composition Sc0.20V0.20Ti0.20Hf0.20Nb0.20, crystallizing in a body-centered cubic crystal structure (Im3 m ¯ ). Our investigation, using magnetization, transport, and heat capacity measurements, reveals the presence of weakly coupled, fully gapped superconductivity with a transition temperature of 4.17(3) K and the upper critical field exceeding the Pauli paramagnetic limit. The metallic nature, combined with a high upper critical field, positions it as a promising candidate for applications in superconducting devices. [ABSTRACT FROM AUTHOR]

A variable coefficient segmented iron loss calculation model is proposed for high‐voltage multi‐pole asynchronous motors, which fully considers the influence of high‐order harmonic magnetic density on such motors. This model introduces additional hysteresis loss, improved eddy current loss coefficients, and rotation magnetisation coefficients to account for changes in losses due to small hysteresis loops and skin effect, as well as rotation magnetisation losses. A 710 kW 10‐pole asynchronous motor is used as the research object. A full‐domain iron loss calculation model considering stator and rotor tooth top surface losses is developed. The model can be used to accurately calculate the overall and local harmonic iron losses in the stator and rotor cores of high‐voltage multi‐pole asynchronous motors. And quantitatively analyse the distribution pattern of any harmonic iron loss at any location in the motor core. It realises the refinement calculation and analysis of iron losses in the whole domain of high‐voltage multi‐pole asynchronous motor. Finally, no‐load and load tests were conducted on the 710 kW 10‐pole asynchronous motor. The iron losses of the 710 kW 10‐pole asynchronous motor at no load and load are calculated using the above mentioned model and the classical trinomial constant factor model. The results are compared with the measured iron loss values. It is proved that the iron loss model is more accurate in calculating the iron loss of high‐voltage multi‐pole asynchronous motor. The result helps researchers to calculate the iron loss distribution of high voltage motors more accurately. Thus, the design and operating parameters of the motor can be optimised to improve the efficiency and performance of the motor. It provides the necessary technical support and key basis for the reduction of loss and energy saving of high‐voltage motors and the optimisation of their core structure. [ABSTRACT FROM AUTHOR]

This study proposes an on-line minimum loss (ML) control strategy that considers the iron and copper losses of an interior permanent magnet synchronous motor in torque-controlled applications. The proposed ML control strategy utilizes a constrained optimization problem to satisfy torque reference tracking and loss minimization. An equivalent iron loss resistance circuit is adopted for the loss minimization. To solve the optimization problem, the Lagrange multiplier method is applied through a numerical analysis algorithm. The resulting solution provides the optimal current reference for every sampling instant. The Lagrange multiplier method needs parameters such as magnetic flux linkages, dynamic inductances, and iron loss resistance. Fundamental magnetic flux linkages are estimated using a flux observer, and the dynamic inductances are estimated with high-frequency voltage signal injection. The proposed iron loss resistance estimator estimates the equivalent iron resistance without any preliminary experiments. DC input power is measured using a current sensor for the accurate on-line estimation of iron loss resistance. To analyze the effectiveness of ML control compared with conventional maximum torque per ampere control, finite element analysis is used. The feasibility of the proposed ML control strategy is verified through simulation and experiments. [ABSTRACT FROM AUTHOR]

We propose a theoretical framework for generating gapless topological superconductivity (GTSC) hosting Majorana flat edge modes (MFEMs) in the presence of a two-dimensional (2D) array of magnetic adatoms with noncollinear spin texture deposited on top of an unconventional superconductor. Our observations reveal two distinct topological phase transitions within the emergent Shiba band depending on the exchange coupling strength (J) between magnetic adatom spins and superconducting electrons: the first one designates transition from gapless non-topological to gapless topological phase at lower J, while the second one denotes transition from gapless topological to a trivial gapped superconducting phase at higher J. The gapless topological superconducting phase survives at intermediate values of J, hosting MFEMs. Furthermore, we investigate the nature of the bulk effective pairings, which indicate that GTSC appears due to the interplay between pseudo "s-wave" and pseudo " p x + p y " types of pairing. Consequently, our study opens a promising avenue for the experimental realization of GTSC in 2D Shiba lattice based on d-wave superconductors as a high-temperature platform. [ABSTRACT FROM AUTHOR]

High-quality titanium nitride (TiN) films with different crystal orientations (001, 110, and 111) obtained under the same growth conditions are systematically investigated by both ultra-low temperature scanning tunneling microscope/spectroscopy and transport experiments. Our results reveal that all of them are conventional type-II superconductors, which exhibit spatially homogeneous superconducting properties. The superconductivity is uniform between surface and bulk. Intriguingly, the TiN (111) film has the highest transition temperature (Tc) but the lowest upper critical field (Hc2). This crystal orientation-dependent superconductivity could be explained by the fact that TiN (001) and TiN (110) films are dirtier than TiN (111). Our results suggest that (111)-oriented TiN is superior to design certain superconducting devices, including Josephson junction devices. The crystallographic orientation could offer an effective controlling parameter for designing TiN-based superconducting devices. [ABSTRACT FROM AUTHOR]

The sensitive response of antiferromagnetic order to As ions height in pressure environment makes the reduction of As ions height beneficial for rapid suppression of antiferromagnetism. The analysis from lattice parameters and electron density indicates that As ions height has a significant impact on antiferromagnetic suppression. The interrelationship between As ions height and antiferromagnetic suppression makes it easier for uniaxial pressure along the c‐axis environments to suppress antiferromagnetism, cause Lifshitz transition compared and induce Fermi surface nesting than uniaxial pressure along the a‐axis (or b‐axis) environments, which can explain the fluctuation of superconducting critical pressure measurements in experiments with uneven pressure application from a microscopic perspective. [ABSTRACT FROM AUTHOR]

Toward low-energy-consumption spintronic devices, magnetic multilayers that host chiral spin textures, as well as efficient spin-torques, are highly promising. As compared with resistive materials, superconducting materials are optimal for constructing dissipationless electronic devices, in which the electricity is conducted without producing Joule heating. In this regard, magnetic multilayers containing superconductors are well suited for building ultra-low power spintronic devices. Following this motivation, we study the possible existence of chiral spin textures in the two-dimensional (2D) high temperature superconductor/ferrimagnet heterostructures of stacking order Bi2Sr2CaCu2O8+δ/Fe1−xTbx and stacking order Bi2Sr2CaCu2O8+δ/Co1−xTbx. Through x-ray photon-emission electron microscopy, we observe bubble-like spin textures in a wide temperature range. Based on the first-principles calculations, the important role of spin–orbit interaction from the BiO termination layer is discussed, which induces a very large interfacial Dzyaloshinskii–Moriya interaction and results in the possible existence of chiral spin textures on top of superconductors. Our work suggests that the layered high-temperature superconductor could be incorporated for stabilizing chiral spin textures and for building dissipationless spin-orbitronic devices. [ABSTRACT FROM AUTHOR]

We present a complete computational study devoted to the deposition of a magnetic binuclear complex on a metallic surface, aimed to obtain insight into the interaction of magnetically coupled complexes with their supporting substrates, as well as their response to external electrical stimuli applied through a surface-molecule-STM molecular junction-like architecture. Our results not only show that the deposition is favorable in two of the four studied orientations, but also, that the magnetic coupling is only slightly perturbed once the complex is adsorbed. We observe that the effects of the applied bias voltage on the magnetic coupling strongly depend on the molecule orientation with respect to the surface and the voltage polarity. Further analysis shows that this behavior is attributable to the stabilization/destabilization of the d-type singly occupied orbitals of the iron centers, reinforced by the strong local electric fields and induced charge densities only present in certain orientations of the deposited molecule and applied voltage polarity. [ABSTRACT FROM AUTHOR]

Vortices and bound states offer an effective means of comprehending the electronic properties of superconductors. Recently, surface-dependent vortex core states have been observed in the newly discovered kagome superconductors CsV 3 Sb 5. Although the spatial distribution of the sharp zero energy conductance peak appears similar to Majorana bound states arising from the superconducting Dirac surface states, its origin remains elusive. In this study, we present observations of tunable vortex bound states (VBSs) in two chemically-doped kagome superconductors Cs(V 1− x Tr x) 3 Sb 5 (Tr = Ta or Ti), using low-temperature scanning tunneling microscopy/spectroscopy. The CsV 3 Sb 5 -derived kagome superconductors exhibit full-gap-pairing superconductivity accompanied by the absence of long-range charge orders, in contrast to pristine CsV 3 Sb 5. Zero-energy conductance maps demonstrate a field-driven continuous reorientation transition of the vortex lattice, suggesting multiband superconductivity. The Ta-doped CsV 3 Sb 5 displays the conventional cross-shaped spatial evolution of Caroli-de Gennes-Matricon bound states, while the Ti-doped CsV 3 Sb 5 exhibits a sharp, non-split zero-bias conductance peak (ZBCP) that persists over a long distance across the vortex. The spatial evolution of the non-split ZBCP is robust against surface effects and external magnetic field but is related to the doping concentrations. Our study reveals the tunable VBSs in multiband chemically-doped CsV 3 Sb 5 system and offers fresh insights into previously reported Y-shaped ZBCP in a non-quantum-limit condition at the surface of kagome superconductor. [ABSTRACT FROM AUTHOR]

We explored superconductors with high superconducting transition temperatures (Tc) tuning the stability of Magnéli phase through high-pressure torsion (HPT). This study has started from exploring superconducting states in the Al–Mg–O ternary system along with the prediction using machine learning. We successfully found superconducting states with Tc = 4.0 and 7.3 K for a composition of Al:Ti = 1:2 in the mixture of Al and surface-oxidized Ti powders. Another magnetic anomaly was also observed at ~ 93 K, being supported by the Tc prediction using the machine learning for the Al–Ti–O system. In this study, the HPT processing was also performed on a Magnéli material Ti4O7 and such mixtures of stable materials as Al + TiO2, Al2O3 + Ti, Al2O3 + TiO2, and Al + Ti4O7. In HPT-processed Ti4O7, the metal–insulator transition was maintained even after the HPT processing. HPT experiments using stable oxides indicate the difficulty of newly stabilizing the Magnéli phase starting from thermodynamically stable materials under severe plastic deformation. A series of attempts reveals that the superconducting state in the mixture with ratio Al:Ti = 1:2 is attributed to both strained Ti-oxide created on the surface of the Ti powder and its reaction with Al under HPT processing, resulting in the stabilization of a Magnéli phase. [ABSTRACT FROM AUTHOR]

A sample of Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 doped with four different ions was prepared using the solid method and a subsequent procedure. X-ray diffraction (XRD), energy-dispersive X-ray (EDX), and scanning electron microscope (SEM) were used to analyze the sample's structural features, elemental distribution, and surface morphology. The study used the B-H magnetic characteristic analyzer and superconducting quantum interferometer magnetic performance measurement system to analyze the magnetic properties of Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12. The correlation becomes more surprising as the frequency increases, indicating a decrease in permeability when the magnetic field H reaches 200 A/m. Ion substitution leads to changes in magnetic crystal anisotropy, affecting permeability as the external magnetic field strength increases. We analyze the correlation between saturation magnetization and temperature in the 520–540 K range and explain the variation of saturation magnetization with temperature. The study shows that saturation magnetization decreases as temperature increases. This result suggests that saturation magnetization decreases as temperature increases. The increased super-exchange effect due to Ti and Mn occupying the (d) sites is much stronger than the reduced effect caused by Sn occupying the (a) sites. Therefore, the saturation magnetization of the Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 sample is higher than that of the undoped sample. The Curie temperature (Tc) of the Y2.85Ca0.15Sn0.08Ti0.05Mn0.07Fe4.8O12 sample is lower than that of the undoped sample. [ABSTRACT FROM AUTHOR]

Topological photonics has been widely investigated due to its profound physical significance and great number of potential applications. Microwaves have long wavelengths, so it is relatively easy to manufacture large-sized microwave photonic crystals, enabling researchers to observe and measure phenomena such as topological boundary states. Nevertheless, the quality factors (QFs) of most resonators composed of traditional materials in the microwave region are relatively low, leading to topological edge states with high decay rates. In this study, we present a one-dimensional topological photonic crystal in the microwave region based on coupled superconducting resonators. A topological state with a QF as high as 6000 is observed, which proves this to be a new platform for the investigation of topological photonics with low decay rates in the microwave regime. [ABSTRACT FROM AUTHOR]

To date, superconductivity in fullerides has been almost exclusively tuned by (chemical or physical) pressure control of the conduction bandwidth, W at half filling. This contrasts sharply with the extensive control of the superconducting transition temperature, T c in atom-based superconductors such as the cuprates and iron pnictides and chalcogenides via changes in valence (bandfilling). Here, we investigate the effect of doping away from the exactly half-filled C 6 0 3 − level in quaternary face-centered-cubic (fcc) — structured fulleride solids with nominal composition ( Rb 2. 5 − x Csx) Ba 0. 5 C 6 0 (0 ≤ x ≤ 2. 5), in which divalent Ba 2 + ions partially replace monovalent alkali Rb + / Cs + ions. The resulting charged-modified fullerides in which the t 1 u bandwidth is also varied with changing x show a dome-shaped dependence of T c on interfullerene separation in analogy with their half-filled antecedents. However, following electron injection beyond half-filling, the superconductivity dome is found to shift towards shorter interfullerene separations, i.e. towards increased conduction bandwidths. [ABSTRACT FROM AUTHOR]

Superconductor/ferroelectric heterostructures are very important for fundamental research and applications since superconductivity can be controlled by electric fields via ferroelectric polarization/piezostrain. Superconductivity is a macroscopic quantum phenomenon and it is commonly believed that the in‐plane superconducting transition temperature (Tc) should be isotropic for superconductors with crystal structures of stacking layers (quasi 2D). Here, the observation of piezostrain‐induced in‐plane anisotropy of Tc in FeSe0.5Te0.5 (FST) thin films grown on ferroelectric single crystals is reported. The as‐prepared FST shows a tetragonal phase with equal in‐plane lattice parameters and an absence of in‐plane anisotropy of Tc. Upon applying electric fields, piezostrain induces a difference in the in‐plane lattice parameters (a‐b) and in‐plane anisotropy of Tc. The in‐plane anisotropy of Tc correlates with a‐b and becomes more remarkable for larger values of a‐b. Some possible extrinsic effects are ruled out by experiments and analysis. A possible mechanism is proposed involving electronic nematicity and inhomogeneous superconductivity in FST to account for this unusual phenomenon. This work is significant for uncovering the exotic nature of unconventional superconductors, as well as applications. [ABSTRACT FROM AUTHOR]

With the gradual promotion of new energy technologies, there is a growing demand for capacitors with high energy storage density, high operating temperature, high operating voltage, and good temperature stability. In recent years, researchers have been devoted to improving the energy storage properties of lead‐based, titanium‐based, and iron‐based multilayer ceramic capacitors (MLCCs). However, limited research has been conducted into MLCC development using NaNbO3 (NN)‐based materials. In this paper, the successful achievement of excellent overall energy storage performance in a novel NaNbO3–(Bi0.5Na0.5)TiO3–Bi(Mg0.5Hf0.5)O3 lead‐free MLCCs is presented. The disordered tilting around the cp axis, disrupts Na and Bi ions' long‐range displacements and induces PNRs and strong relaxor behavior, which ensures a superior energy storage performance, together with the multilayer ceramic design strategy. As a result, the NN‐based MLCC device presents an ultra‐high Wrec = 12.65 J cm−3 and η = 88.5%, simultaneously showing superior temperature stability (Wrec varies <±1% and η varies <±6% from −50 to 125 °C) and fatigue resistance (Wrec and η vary <±1% over 107 cycles). This study highlights the advanced energy storage potential of NaNbO3‐based MLCCs for various applications, and ushers in a new era for designing high‐performance lead‐free capacitors that can operate in harsh environments. [ABSTRACT FROM AUTHOR]

The rapid growth of artificial intelligence is revolutionizing classical engineering society, offering novel approaches to material and structural design and analysis. Among various scientific machine learning techniques, physics-informed neural network (PINN) has been one of the most researched subjects, for its ability to incorporate physics prior knowledge into model training. However, the intrinsic continuity requirement of PINN demands the adoption of domain decomposition when multiple materials with distinct properties exist. This greatly complicates the gradient computation of design features, restricting the application of PINN to structural shape optimization. To address this, we present a novel framework that employs neural network coordinate projection for shape optimization within PINN. This technique allows for direct mapping from a standard shape to its optimal counterpart, optimizing the design objective without the need for traditional transition functions or the definition of intermediate material properties. Our method demonstrates a high degree of adaptability, allowing the incorporation of diverse constraints and objectives directly as training penalties. The proposed approach is tested on magnetostatic problems for iron core shape optimization, a scenario typically plagued by the high permeability contrast between materials. Validation with finite-element analysis confirms the accuracy and efficiency of our approach. The results highlight the framework's capability as a viable tool for shape optimization in complex material design tasks. [ABSTRACT FROM AUTHOR]

We have investigated the effect of the Ni substitution on the local structure and the valence electronic states of the SrFe 2 − x Ni x As 2 (x = 0.00, 0.16, and 0.23) superconductor with a multi-edge extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy. The As K-edge and Fe K-edge EXAFS measurements in the two polarizations (E‖ab and E‖c) show a clear change in the local structure with Ni concentration. The near-neighbor bondlengths and the related mean-square relative displacements (MSRDs) decrease as the Ni content increases. The polarized XANES spectra at the As, Fe and Ni K edges reveal a systematic change in the anisotropy of the valence electronic structure. The results suggest that the quasi 2D electronic structure of this system tends to become more isotropic as the Ni content increases. The local structure and the valence electronic states are discussed in the frame of the evolving electronic transport of the SrFe 2 − x Ni x As 2 system. [ABSTRACT FROM AUTHOR]

Recent refinements on a semiclassical approach are reviewed, aiming at describing the inhomogeneous local gap parameter in the presence of non-trivial spatial geometries and at taking into account at the same time pairing fluctuations beyond mean field. The method is applied to describe the Josephson effect over the wide range of physical conditions related to recent experiments on this topic performed with ultra-cold Fermi gases. [ABSTRACT FROM AUTHOR]

Low-temperature scanning tunneling microscopy and spectroscopy (STM/S) help to better understand the fundamental physics of condensed matter. We present an ultracompact STM within a Φ 10 piezo tube in a 20 T superconducting magnet. The carefully cut piezo tube contains the STM's coarse-positioning assembly. Loading an STM tip–sample mechanical loop into the piezo tube with special cut openings enables an ultracompact pencil-size dimension down to Φ 10 mm, in which fine-machined nonmagnetic parts are assembled to enable slide–stick motion and xyz-scanning procedures. The small size leads to a higher resonant frequency, a typical feature of a rigid STM instrument, increasing its vibration immunity. Scanning by moving the sample while keeping the tip stationary improves the stability of the tip–sample junction compared to moving the tip. Taking advantage of its high-field compatibility and rigid design, our STM captures the atomically resolved topography of highly oriented pyrolytic graphite (HOPG) at 1.5 K and in magnetic fields up to 17 T. The topography of graphene lattice and graphite is simultaneously recorded on an atomic terrace of HOPG, unveiling a modified local charge density at a surface defect. The superconducting energy gaps of layered type-II superconductors NbSe2 and PdBi2 are well resolved through dI/dV tunneling spectra at sub-2 K. Our unique STM is highly suitable for potential STM/S applications in world-class high-field facilities where the strong magnetic field can exceed 30 T. [ABSTRACT FROM AUTHOR]

In this research work, we report the synthesis, crystal structure, Raman Study, and magnetic properties at low temperatures of TaCx (x = 0.00, 1.25, and 1.50) compounds. The experiments are performed on polycrystalline samples synthesized by an arc melting method. The samples show a cubic phase with FFC structure measurements by XRD and were further analyzed by Rietveld refinements in which the small impurity of the Ta2C and T2O5 was detected. Raman spectroscopy shows the characteristics of TaC peaks being associated with disordered band (D) and graphitic band (G). The transmission electron microscopy study was performed to obtain the morphology, size, and microstructure of the samples. The magnetic property magnetization curves in zero field cooling (ZFC) and field cooling (FC) modes reveal that the system is characterized as a type II superconductor. The most important aspect of this study is observed with the increase of C doping amount; the Tc presents a slightly increasing tendency from 9 K to 9.5 K. [ABSTRACT FROM AUTHOR]

The current research addresses a unified and integrated Euler–Lagrange simulation platform based on the extended discrete element method that advances significantly the digital twin technology applied to blast furnaces. It includes a particulate phase characterized by its dynamic and thermodynamic state that is coupled to multiphase computational fluid dynamics (CFD) by heat, mass, and momentum transfer. Thus, the framework deals with transient and reacting 3D granular and multiphase flows. The latter includes all relevant processes taking place in a blast furnace: formation of a reducing agent, e.g., carbon monoxide, reduction of iron‐bearing material, and softening and melting with the subsequent transfer into the corresponding phase of the multiphase CFD solver and thus, identifying unambiguously the cohesive zone. Validation is carried out on different length scales from a particle level to the global dimensions of a blast furnace and shows a good agreement between predictions and experimental data. Applying fast and innovative algorithms allows for moderate computational times, i.e., 1000 s real‐time takes ≈2.3 d on an Intel(R) Xenon(R) Silver 4114 CPU @ 2.2 GHz processor with 40 cores and the entire domain divides into eight partitions. [ABSTRACT FROM AUTHOR]

The Ordovician–Devonian Sierra Grande Formation, Río Negro Province, Argentina contains three quarzitic members with two iron horizons. Its South Deposit includes both iron horizons. However, the East Deposit is relatively unknown, lacking information about geometry, depth and reserves. To answer these questions, we apply geophysical methods for the rapid evaluation of the East Deposit, using gravity and magnetic measures. The processing of these data allows the suggestion of two 2D models for calculating thicknesses, angles and depth of the iron horizons. The adjustments between the calculated and the observed curve are less than 6%. One model proposes the existence of the Alfaro iron horizon, and the other one proposes the presence of the Rosales iron horizon at depth. The Bouguer anomaly gravimetric maps allow us to calculate the mineral mass, resulting in 125 million iron tons. Thus, this study allowed us to calculate the thicknesses, angles and depth of both iron horizons, and to adjust and evaluate the mineral reserves with the maximum reliability that potential methods allow when applied to mineral prospecting. These results provide new and valuable information for future mining prospects. [ABSTRACT FROM AUTHOR]

We consider the effect of the nematic order on the formation of the superconducting state in iron pnictides and chalcogenides. Nematic order with the symmetry is modelled as the d-type Pomeranchuk instability and treated within the mean-field approach. Calculated nematic order parameter depends on the nematic interaction coefficient and abruptly changes with the coefficient's increase. The superconducting solution is obtained within the spin-fluctuation pairing theory. We show that the leading solution in the nematic phase has a structure. From the critical temperature estimations, we conclude that the nematic superconducting state of the type is more favorable than the usual and type states appearing in the absence of the nematicity. [ABSTRACT FROM AUTHOR]

The combination of strongly coupled Cooper pairs and weak superconducting fluctuations is an important prerequisite for achieving high-temperature superconductivity. The review is devoted to the implementation of this condition in multiband superconductors, in which strongly coupled pairs in the shallow conduction band (the Fermi level is close to the band edge) coexist with ordinary, weakly fluctuating Cooper pairs formed in the deep band. As a result of the Josephson coupling between condensates in different bands, such a system is characterized by a high critical coherence temperature due to the presence of strongly coupled pairs and the suppression of superconducting fluctuations. This suppression does not require any special preconditions, and is almost total even if the Josephson coupling between the bands is weak. [ABSTRACT FROM AUTHOR]

A comprehensive study of magnetotransport and field‐dependent specific heat of FeTe0.58Se0.42 single crystals synthesized using the self‐flux method is reported. The transport measurement reveals the presence of Fermi liquid behavior in the normal state resistivity of the single crystals. Furthermore, the grown single crystals exhibit anisotropy and demonstrate a high value of upper critical magnetic field (HC2). The magnetoresistance exhibits a linear behavior as the magnetic field increases, suggesting the possible presence of a Dirac‐cone state. Anisotropy is also observed in magnetoresistance near the superconducting transition temperature (TC). The sign reversal of the Hall coefficient and the violation of Kohler's rules are observed, which provide evidence of the presence of multiband effects in FeTe0.58Se0.42 single crystals. Specific heat measurements confirm the bulk superconductivity in the grown single crystals. Additionally, the specific heat jump ΔC(TC)/TC is estimated, which is approximately equal to 26 mJ mol−1 K−2. The magnetic field‐dependent specific heat also suggests multiband superconductivity and offers insights into the upper critical field. Furthermore, the electronic specific heat (Cel) is best fitted with a two‐band model. Moreover, the field‐dependent residual Sommerfeld coefficient γ(H) gives information about the superconducting pairing symmetry. [ABSTRACT FROM AUTHOR]

The interface between two different materials can show unexpected quantum phenomena. In this study, we used molecular beam epitaxy to synthesize heterostructures formed by stacking together two magnetic materials, a ferromagnetic topological insulator (TI) and an antiferromagnetic iron chalcogenide (FeTe). We observed emergent interface-induced superconductivity in these heterostructures and demonstrated the co-occurrence of superconductivity, ferromagnetism, and topological band structure in the magnetic TI layer-the three essential ingredients of chiral topological superconductivity (TSC). The unusual coexistence of ferromagnetism and superconductivity is accompanied by a high upper critical magnetic field that exceeds the Pauli paramagnetic limit for conventional superconductors at low temperatures. These magnetic TI/FeTe heterostructures with robust superconductivity and atomically sharp interfaces provide an ideal wafer-scale platform for the exploration of chiral TSC and Majorana physics. [ABSTRACT FROM AUTHOR]

The recently discovered superconductor UTe2 is a promising candidate for spin-triplet superconductors, but the symmetry of the superconducting order parameter remains highly controversial. Here, we determine the superconducting gap structure by the thermal conductivity of ultraclean UTe2 single crystals. We find that the a-axis thermal conductivity divided by temperature κ/T in zero-temperature limit is vanishingly small for both magnetic field H‖a and H‖c axes up to H/Hc2 ~ 0.2, demonstrating the absence of nodes around the a axis contrary to the previous belief. The present results, combined with the reduction of nuclear magnetic resonance Knight shift, indicate that the superconducting order parameter belongs to the isotropic Au representation with a fully gapped pairing state, analogous to the B phase of superfluid 3He. These findings reveal that UTe2 is likely to be a long-sought three-dimensional strong topological superconductor, hosting helical Majorana surface states on any crystal plane. [ABSTRACT FROM AUTHOR]

The paper reports complementary studies of the order parameter of the newly discovered iron-based superconductor, KCa2Fe4As4F2 (Tc = 34 K), that consists of alternating blocks of KFe2As2 (122) phase and CaFeAsF (1111) phase. We performed high-resolution intrinsic multiple Andreev reflection spectroscopy supplemented with self-field critical current measurements. Andreev spectra obtained by means of a break-junction technique reveal two distinct superconducting order parameters ΔL and ΔS. Their temperature dependencies were measured from 1.5 K to Tc. The shapes of Andreev reflections dips, corresponding to the two gaps are symmetrical, which is a signature of s-wave order parameter. Temperature dependence of the self-field critical current can also be described by two s-wave gaps model. [ABSTRACT FROM AUTHOR]

For enhancing the charge storage of nanoparticles by modifying the grains, a novel lithium-doped iron-based nanoparticle (Li2xMn1–xFe2O4) was designed and synthesized. Lithium-doped manganese ferrite (Li2xMn1–xFe2O4) nanoparticles were prepared using sol–gel route with different doping concentrations of lithium, i.e., x = 0, 0.25, 0.50, 0.75, and 1.0 when annealed at 500 °C temperature. The structure (crystal structure and crystallite size), vibrational modes (functional groups of molecules), morphology, and composition were investigated and confirmed by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The vibrational bands shifted towards high wavenumbers due to small ionic radii of Li+1 to Mn+2 which indicated the successful replacement of lithium with manganese in Li2xMn1–xFe2O4 nanoparticles and redistribution of cations between octahedral and tetrahedral sites. Moreover, the dielectric parameters of Li2xMn1–xFe2O4 nanoparticles were investigated using LCR at room temperature. The dielectric parameters revealed improved dielectric properties ( ε r ′ 168, ε r ″ 332, tanδ 2.63, and σac 3.78 × 10–4 Ω−1 m−1) with increasing concentrations of lithium in Li2xMn1–xFe2O4 nanoparticles owed to increasing Fe2+ ions at the octahedral sites. Furthermore, these Li2xMn1–xFe2O4 nanoparticles offered large places and provoke more active sites for storage due to their high ac-conductivity. Henceforth, it can be suggested that lithium-doped manganese ferrite nanoparticles can be the best candidate for energy storage devices. [ABSTRACT FROM AUTHOR]

The ability to realistically simulate the electronic structure of superconducting materials is important to understand and predict various properties emerging in both the superconducting topological and spintronics realms. We introduce a tight-binding implementation of the Bogoliubov–de Gennes method, parameterized from density functional theory, which we utilize to explore the bulk and thin films of Nb, known to host a significant superconducting gap. The latter is useful for various applications such as the exploration of trivial and topological in-gap states. Here, we focus on the simulation's aspects of superconductivity and study the impact of temperature, Cooper-pair coupling and dimensionality on the value of the superconducting pairing interactions and gaps. [ABSTRACT FROM AUTHOR]

Topological superconductors have drawn significant interest from the scientific community due to the accompanying Majorana fermions. Here, the discovery of electronic structure and superconductivity (SC) in high‐entropy ceramics Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx (x = 1 and 0.8) combined with experiments and first‐principles calculations is reported. The Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2Cx high‐entropy ceramics show bulk type‐II SC with Tc ≈ 4.00 K (x = 1) and 2.65 K (x = 0.8), respectively. The specific heat jump (∆C/γTc) is equal to 1.45 (x = 1) and 1.52 (x = 0.8), close to the expected value of 1.43 for the BCS superconductor in the weak coupling limit. The high‐pressure resistance measurements show a robust SC against high physical pressure in Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, with a slight Tc variation of 0.3 K within 82.5 GPa. Furthermore, the first‐principles calculations indicate that the Dirac‐like point exists in the electronic band structures of Ti0.2Zr0.2Nb0.2Mo0.2Ta0.2C, which is potentially a topological superconductor. The Dirac‐like point is mainly contributed by the d orbitals of transition metals M and the p orbitals of C. The high‐entropy ceramics provide an excellent platform for the fabrication of novel quantum devices, and the study may spark significant future physics investigations in this intriguing material. [ABSTRACT FROM AUTHOR]

The interplay between superconductivity and magnetism has been a subject of significant interest for decades. While extensive research has focused on modifying the superconducting state through a magnetic domain as an independent variable, the manipulation of magnetic domains by the superconducting state has been relatively unexplored, primarily due to their higher stiffness compared to the energy associated with superconducting vortices. In this Letter, we demonstrate the manipulation of magnetic domains by thermally activated superconducting vortices in a ferromagnet/superconductor hybrid. We observe a reversible domain transition between metastable magnetic stripes and bubbles in a Nb/CeRu2Ga2B hybrid induced by vortex motion and the trapped field within the Nb superconducting film. The comparable Curie and superconducting critical temperatures and the presence of magnetic metastable states enable the magnetic domain changes driven by superconducting vortices in this hybrid system. [ABSTRACT FROM AUTHOR]

Diamond-type structure allotrope α-Sn is attracting much attention as a topological Dirac semimetal (TDS). In this study, we demonstrate that α-Sn undergoes a phase transition to another allotrope β-Sn with superconductivity at low temperature by irradiating with a focused Ga ion beam (FIB). To clarify the transition mechanism, we performed x-ray photoemission spectroscopy (XPS) measurements on an α-Sn thin film irradiated with FIB and an as-grown α-Sn thin film. The XPS results suggest that the local annealing, which is one of the side effects of FIB, causes the transformation from α-Sn into β-Sn. Furthermore, the difference in the chemical states between α-Sn and β-Sn can be quantitatively explained by the crystal structures rather than the degree of metallicity reflecting the conductivity. These results propose a way of fabricating TDS/superconductor in-plane heterostructures based on α-Sn and β-Sn. [ABSTRACT FROM AUTHOR]

The recently discovered kagome superconductors offer a promising platform for investigating intertwined orders and novel states, including topology, superconductivity, charge density waves, and more. The interplay among these orders can spontaneously break rotational symmetry, giving rise to exotic phenomena such as nematicity or even nematic superconductivity. Here we present our findings on the two-fold symmetric superconductivity in thin-flake RbV3Sb5 in response to direction-dependent in-plane magnetic fields, in contrast to the inherent six-fold structural symmetry of the crystal lattice. The two-fold symmetry was evidenced through a combination of magnetoresistance transport experiments, critical magnetic field measurements, and observations of anisotropic superconducting gaps. Additionally, by altering the experimental configuration, we also detected the presence of six-fold symmetric components superimposed on the two-fold symmetry at the boundary between normal and superconducting states. Our results underscore the correlation-driven symmetry-breaking phenomena and emphasize the potential of this correlated kagome family as a promising platform for investigating intertwined orders, including unconventional superconductivity. Kagome materials provide a platform to investigate the interplay between a range of ordered phases such as charge density waves, superconductivity, as well as non-trivial topological properties. Here, the authors observed the two-fold symmetric superconductivity in RbV3Sb5, which suggests the presence of unconventional superconductivity involved with nematic states and spin-orbit-parity coupled superconductivity. [ABSTRACT FROM AUTHOR]

Understanding the pairing symmetry is a crucial theoretical aspect in the study of unconventional superconductivity for interpreting experimental results. Here we study superconductivity of electron systems with both spin and pseudospin-1/2 degrees of freedom. By solving linearized gap equations, we derive a weak coupling criterion for the even-parity spin-singlet pseudospin-triplet pairing. It can generally mix with the on-site s-wave pairing since both of them belong to the same symmetry representation (A1g) and their mixture could naturally give rise to anisotropic intra-band pairing gap functions with or without nodes. This may directly explain why some of the iron-chalcogenide superconductors are fully gapped (e.g. FeSe thin film) and some have nodes (e.g. LaFePO and LiFeP). We also find that the anisotropy of gap functions can be enhanced when the principal rotation symmetry is spontaneously broken in the normal state such as nematicity, and the energetic stabilization of pseudospin-triplet pairings indicates the coexistence of nematicity and superconductivity. This could be potentially applied to bulk FeSe, where gap anisotropy has been experimentally observed. The underlying symmetry of a given system dictates the material properties from the electronic band structure to its spontaneous symmetry broken ordering. Here, the authors consider the effects of symmetry breaking and investigate spin-singlet orbital triplet pairings in unconventional superconductors with electronic nematicity, they apply their results to iron-based superconductors and twisted bilayer graphene. [ABSTRACT FROM AUTHOR]

Two-dimensional Ising superconductivity formed in NbSe2, MoS2, WS2, etc. transition-metal dichalcogenides is considered. For the superconducting state, the effective low-energy action for phases of the order parameters has been obtained and collective modes in the system have been studied. It has been shown that the system contains not only the Goldstone mode but also the Leggett mode with a mass related to the difference between the singlet and triplet pairing constants. The effect of a low magnetic field parallel to the plane of the system has also been discussed. [ABSTRACT FROM AUTHOR]

As compressed hydrides constantly refresh the records of superconducting critical temperatures (Tc) in the vicinity of room temperature, this further reinforces the confidence to find more high-temperature superconducting hydrides. In this process, metastable phases of superhydrides offer enough possibilities to access superior superconducting properties. Here we report a metastable hexagonal lanthanum superhydride (P 63 /mmc -LaH10) stabilized at 146 GPa by introducing an appropriate proportion of Al, which exhibits high-temperature superconductivity with Tc ∼ 178 K, and this value is enhanced to a maximum Tc ∼ 223 K at 164 GPa. A huge upper critical magnetic field value Hc2(0) reaches 223 T at 146 GPa. The small volume expansion of P 63 /mmc -(La, Al) H10 compared with the binary LaH10 indicates the possible interstitial sites of Al atoms filling into the La–H lattice, instead of forming conventional ternary alloy-based superhydrides. This work provides a new strategy for metastable high-temperature superconductors through the multiple-element system. [ABSTRACT FROM AUTHOR]

Thallium-based high-temperature superconductors exhibit excellent superconductivity performance (Tc, Jc). Formation of the Tl-based superconducting materials critically depends on the used precursor and synthesis conditions. In the present investigation, we used the in situ polymerization method for synthesizing high-purity and reaction-ability precursors. We find the critical dependence of Tl-based superconductor phase formation on the quantity of applied oxygen pressure. The experimental results showed that the Tl-1223 phase formed at an oxygen gas pressure at 1 to 2 atm, Tl-2223 phase at 3 atm, and Tl-2212 phase at 4 to 8 atm. [ABSTRACT FROM AUTHOR]

Majorana excitations are the quasiparticle analog of Majorana fermions in solid materials. Typical examples are the Majorana zero modes (MZMs) and the dispersing Majorana modes. When probed by scanning tunneling spectroscopy, the former manifest as a pronounced conductance peak locating precisely at zero-energy, while the latter behaves as constant or slowly varying density of states. The MZMs obey non-abelian statistics and are believed to be building blocks for topological quantum computing, which is highly immune to the environmental noise. Existing MZM platforms include hybrid structures such as topological insulator, semiconducting nanowire or 1D atomic chains on top of a conventional superconductor, and single materials such as the iron-based superconductors (IBSs) and 4Hb–TaS2. Very recently, ordered and tunable MZM lattice has also been realized in IBS LiFeAs, providing a scalable and applicable platform for future topological quantum computation. In this review, we present an overview of the recent local probe studies on MZMs. Classified by the material platforms, we start with the MZMs in the iron-chalcogenide superconductors where FeTe0.55Se0.45 and (Li0.84Fe0.16)OHFeSe will be discussed. We then review the Majorana research in the iron-pnictide superconductors as well as other platforms beyond the IBSs. We further review recent works on ordered and tunable MZM lattice, showing that strain is a feasible tool to tune the topological superconductivity. Finally, we give our summary and perspective on future Majorana research. [ABSTRACT FROM AUTHOR]

[Display omitted] • At OLR of 24.7 gVS/L, CH 4 yields of AD reactor at 45 °C was 536.23 mLCH 4 /gVS. • Fe0 and Fe 3 O 4 played a co-enhancing role in increasing CH 4 yield in AD at 45 °C. • Methanobacterium sp and Syntrophaceticus schinkii were key species in AD at 45 °C. • SAO-HM was main pathway to eliminate acidification and methanogenesis in AD at 45 °C. Deoiling of food waste (FW) after hydrothermal pretreatment occurs at high temperatures, and more energy is required for substrate cooling before the anaerobic digestion (AD) process. AD at the transition temperature (for example 45 °C) is good for energy saving and carbon emission reducing when treating deoiling FW. However, the metabolic activity of methanogens must increase at the transition temperatures. This study proposes the use of zero-valent iron (Fe0) and magnetite (Fe 3 O 4) to boost CH 4 yield from deoiling FW. The results showed a co-enhancing effect on CH 4 yield upgradation when using Fe0 and Fe 3 O 4 simultaneously, and the highest CH 4 yield reached 536.23 mLCH 4 /gVS, which was 67.5 % higher than that of Fe0 alone (320.14 mLCH 4 /gVS). In addition, a high organic loading was favorable for increasing the CH 4 yield from deoiling FW. Microbial diversity analysis suggested that the dominant methanogenic pathway at 45 °C was hydrogenotrophic methanogenesis. Herein, a potential metabolic pathway analysis revealed that the co-enhancing effects of Fe0 and Fe 3 O 4 enhanced syntrophic methanogenesis and possibly boosted electron transfer efficiency. [ABSTRACT FROM AUTHOR]

We synthesize the Weyl semimetal/superconductor NbP/NbSe2 composite and observe stable bulk superconductivity at Tc = 7.2, 6.9, and 6.8 K for the NbSe2 crystal, NbP/NbSe2 (1:1), and NbP/NbSe2 (2:1) composites, respectively, despite large volume fraction of the non-superconducting NbP phase. From the Ginzburg–Landau theory, Hc2(0) is significantly enhanced in NbP/NbSe2 composites [22 T (1:1) and 18.5 T (2:1)] comparing with the pristine NbSe2 crystal (8 T). The bulk superconductivity in the Weyl semimetal/superconductor composite cannot be simply described by the de Gennes–Meissner theory in a proximity effect. From the electrical transport, magnetization, and heat capacity measurement, we obtain various superconducting parameters. The superconducting properties indicate that the NbP/NbSe2 composite is far from the conventional Bardeen–Cooper–Schrieffer superconductivity. It suggests that the Weyl semimetal/superconductor composite can have a giant proximity effect, resulting in the stable bulk superconductivity in a composite with a sizable volume fraction of non-superconducting Weyl semimetals. The giant proximity effect in the Weyl semimetal/superconductor interface can have a platform to investigate the proximity induced Weyl semimetallic superconducting states. [ABSTRACT FROM AUTHOR]