Search

Water confined within nanochannels with specific functionalities serves as the foundation for a variety of emerging nanofluidic applications. However, the structure and dynamics of the confined liquid are susceptibly influenced by practically hard-to-avoid defects, yet knowledge of this fact remains largely unexplored. Here, using extensive molecular dynamics simulations, we elucidate the significant influence of geometric and charge defects on one-dimensional confined water. We show that the two types of defects can both reshape the water density distribution by constraining the translocation of water molecules along the circumferential direction. In addition to structural alterations, collective translocation and rotation of water slabs arise during transportation under external pressure. Below the temperature threshold marking the initiation of liquid-solid transition, the geometric defect retards water diffusion through a pinning effect, while the charge defect induces an anti-freezing effect. The latter is attributed to the electrostatic interaction between the charge defect and water molecules that hinders the formation of a stable hydrogen bond network by disrupting molecular dipole orientation. Consequently, this behavior results in a reduction in the number and lifetime of hydrogen bonds within the phase transition interval. The distinct roles of the two types of defects could be utilized to control the structure and dynamics of confined liquids that may result in distinct functionalities for nanofluidic applications. [ABSTRACT FROM AUTHOR]

An exciton–polariton condensate is a hybrid light–matter state in the quantum fluid phase. The photonic component endows it with characters of spin, as represented by circular polarization. Spin-polarization can form stochastically for quasi-equilibrium exciton–polariton condensates at parallel momentum vector k|| ∼ 0 from bifurcation or deterministically for propagating condensates at k|| > 0 from the optical spin-Hall effect (OSHE). Here, we report deterministic spin-polarization in exciton–polariton condensates at k|| ∼ 0 in microcavities containing methylammonium lead bromide perovskite (CH3NH3PbBr3) single crystals under non-resonant and linearly polarized excitation. We observe two energetically split condensates with opposite circular polarizations and attribute this observation to the presence of strong birefringence, which introduces a large OSHE at k|| ∼ 0 and pins the condensates in a particular spin state. Such spin-polarized exciton–polariton condensates may serve not only as circularly polarized laser sources but also as effective alternatives to ultracold atom Bose–Einstein condensates in quantum simulators of many-body spin–orbit coupling processes. [ABSTRACT FROM AUTHOR]

The effect of the YBCO superconducting (SC) state on the magnetic properties of as-grown YBCO/Co/IrMn heterostructures has been systematically studied using magnetometry and ferromagnetic resonance. The obtained data showed that the superconductivity of the YBCO substrate strongly affects the ferromagnetic properties of the deposited Co layer deeper (up to 50 nm) than the coherence length of the YBCO (≃ 4 nm) by an exchange interaction between the Co magnetic moments and the superconducting pairs at the YBCO/Co interface. The interfacial exchange interaction, switched on while the YBCO enters the SC state, pins Co spins and yields an enhancement of the Co magnetic properties. [ABSTRACT FROM AUTHOR]

Mn 3 Sn, a metallic antiferromagnet with an anti-chiral 120 ° spin structure, generates intriguing magneto-transport signatures such as a large anomalous Hall effect, spin-polarized current with novel symmetries, anomalous Nernst effect, and magneto-optic Kerr effect. When grown epitaxially as MgO(110)[001] ∥ Mn 3 Sn(0 1 ¯ 1 ¯ 0)[0001], Mn 3 Sn experiences a uniaxial tensile strain, which changes the bulk sixfold anisotropy to a twofold perpendicular magnetic anisotropy (PMA). Here, we investigate the field-assisted spin–orbit-torque (SOT)-driven dynamics in single-domain Mn 3 Sn with PMA. We find that for non-zero external magnetic fields, the magnetic octupole moment of Mn 3 Sn can be switched between the two stable states if the input current is between two field-dependent critical currents. Below the lower critical current, the magnetic octupole moment exhibits a stationary state in the vicinity of the initial stable state. On the other hand, above the higher critical current, the magnetic octupole moment shows oscillatory dynamics which could, in principle, be tuned from the 100s of megahertz to the terahertz range. We obtain approximate analytic expressions of the two critical currents that agree very well with the numerical simulations for experimentally relevant magnetic fields. We also obtain a unified functional form of the switching time vs the input current for different magnetic fields. Finally, we show that for lower values of Gilbert damping (α ≲ 2 × 10 − 3 ), the critical currents and the final steady states depend significantly on α. The numerical and analytic results presented in our work can be used by both theorists and experimentalists to understand the SOT-driven order dynamics in PMA Mn 3 Sn and design future experiments and devices. [ABSTRACT FROM AUTHOR]

We report the dynamic characterization of the spin-torque-driven in-plane precession modes of a spin-torque nano-oscillator based on two different synthetic ferrimagnets: a pinned one characterized by a strong Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction, which is exchange-coupled to an antiferromagnetic layer; and a non-pinned one characterized by weak RKKY coupling. The microwave properties associated with the steady-state precession of both synthetic ferrimagnets (SyFs) are characterized by high spectral purity and power spectral density. However, frequency dispersion diagrams of the damped and spin-transfer torque modes reveal drastically different dynamical behavior and microwave emission properties in both SyFs. In particular, the weak coupling between the magnetic layers of the non-pinned SyF raises discontinuous dispersion diagrams suggesting a strong influence of mode crossing. An interpretation of the different dynamical features observed in the damped and spin-torque modes of both SyF systems was obtained by solving simultaneously, in a macrospin approach, a linearized version of the Landau–Lifshitz–Gilbert equation including the spin-transfer torque term. [ABSTRACT FROM AUTHOR]

We have investigated the effect of gamma (γ)-irradiation on the structural and superconducting properties of FeTe0.55Se0.45 single crystals grown by the self-flux method. The impact of γ-irradiation on the superconducting transition temperature (TC), critical current density (JC), and vortex pinning mechanism has been systematically studied. The x-ray diffraction study reveals the growth of single crystals along the c-axis. The superconductivity has been confirmed in pristine and γ-irradiated samples through temperature-dependent resistivity (ρ (T)) and magnetization [M(T)] measurements. After irradiation, a slight improvement is observed in the upper critical field H c 2 (0) values. The values of thermally activated energy have been calculated and a crossover from a single to collective vortex pinning regime is observed. Additionally, we have analyzed the vortex phase diagrams, revealing a transition from vortex liquid to vortex glass state. Furthermore, the presence of second magnetization peak (SMP) or fishtail effect has been noticed in the M(H) loops, and with increasing temperature, the position of SMP (H s p ) shifts toward lower magnetic field regions. The critical current density has been estimated by Bean's critical state model at different magnetic fields [JC(H)] and temperatures [JC(T)]. The defects through gamma-irradiation lead to a significant threefold increase in JC compared to pristine samples in self-field and at 2 K. The pinning mechanisms have been explained using collective pinning theory and the Dew-Hughes model by analyzing the normalized pinning force density. Our analysis indicates that δl-pinning is dominant and point defects are present in all the samples. [ABSTRACT FROM AUTHOR]

In this work, we have performed a first-order reversal curve study of the magnetization process of a top-pinned spin valve when a Pt/Co multilayer with perpendicular to plane anisotropy is deposited on top of the structure, near the pinned layer. We find that the magnetostatic interaction with the Pt/Co multilayer largely alters the magnetization process of both the pinned and the free layer of the spin valve, giving their magnetization a perpendicular-to-plane component, although some areas remain pinned in the plane. With this complex multilayer set, we fabricated nanostrips using a patterned Pt/Co multilayer on top of the spin valve as a pinning point for the magnetic domain wall traveling through the free layer. The Pt/Co feature on top of the spin valve strip pins the domain wall, although only in the return branch of the free layer magnetoresistance loop. The transport measurements show that the associated depinning field of the Pt/Co pinning feature is relatively weak. Nevertheless, the strong influence of the Pt/Co multilayer on the spin valve, visible in the magnetic characterization, indicates that this type of pinning defect may well be a good alternative in some spintronic devices, where the application requires adjusting the pinning strength of the local defects. [ABSTRACT FROM AUTHOR]

Amorphous solids are known to fail catastrophically via fracture, and cavitation at nano-metric scales is known to play a significant role in such a failure process. Micro-alloying via inclusions is often used as a means to increase the fracture toughness of amorphous solids. Modeling such inclusions as randomly pinned particles that only move affinely and do not participate in plastic relaxations, we study how the pinning influences the process of cavitation-driven fracture in an amorphous solid. Using extensive numerical simulations and probing in the athermal quasistatic limit, we show that just by pinning a very small fraction of particles, the tensile strength is increased, and also the cavitation is delayed. Furthermore, the cavitation that is expected to be spatially heterogeneous becomes spatially homogeneous by forming a large number of small cavities instead of a dominant cavity. The observed behavior is rationalized in terms of screening of plastic activity via the pinning centers, characterized by a screening length extracted from the plastic-eigenmodes. [ABSTRACT FROM AUTHOR]

A key development toward new electronic devices integrating memory and processing capabilities could be based on the electric control of the spin texture of charge carriers in semiconductors. In that respect, GeTe has been recently recognized as a promising ferroelectric Rashba semiconductor, with giant spin splitting of the band structure, due to the inversion symmetry breaking arising from ferroelectric polarization. Here, we address the temperature dependence of the ferroelectric structure of GeTe thin films grown on Si(111). We demonstrate the hysteretic behavior of the ferroelectric domain density upon heating/cooling cycles by low energy electron microscopy. This behavior is associated with an abnormal evolution of the GeTe lattice parameter as shown by x-ray diffraction. We explain these thermomechanical phenomena by a large difference of thermal expansion coefficients between the film and the substrate and to the pinning of the GeTe/Si interface. The accumulated elastic energy by the GeTe thin film during sample cooling is released by the formation of a -nanodomains with in-plane ferroelectric polarization components. [ABSTRACT FROM AUTHOR]

The manipulation of spin–orbit torque (SOT) manifests enormous potentiality in the field of spintronics due to virtues of low power consumption, ultrafast spin-flips, and high-density integration. Increaser the spin hall angle of the spin source layer or the SOT efficiency are the key approaches of achieving low power spintronics. Here, we report an enhancement of spin–orbit torques in Ta/Co/Pt heterostructures using low-voltage ionic liquid gating. The effective spin Hall angle increased threefold with an applied voltage of 2 V. As expected, the enhanced spin Hall angle lowers the critical current density by 66.7% (1.14 × 107 to 3.80 × 106 A cm−2). By the lock-in harmonic Hall voltage measurements, the outstanding performance of manipulation of the spin–orbit coupling originates from the electrostatic doping interracially by the ionic liquid. In addition to the significant fundamentals, our work could be feasibly wielded toward the spintronics such as memory and logic devices in the behaviors of energy-efficient and impressive tunability. [ABSTRACT FROM AUTHOR]

Chiral molecules have the potential for creating new magnetic devices by locally manipulating the magnetic properties of metallic surfaces. When chiral polypeptides chemisorb onto ferromagnets, they can induce magnetization locally by spin exchange interactions. However, direct imaging of surface magnetization changes induced by chiral molecules was not previously realized. Here, we use magneto-optical Kerr microscopy to image domains in thin films and show that chiral polypeptides strongly pin domains, increasing the coercive field locally. In our study, we also observe a rotation of the easy magnetic axis toward the out-of-plane, depending on the sample's domain size and the adsorption area. These findings show the potential of chiral molecules to control and manipulate magnetization and open new avenues for future research on the relationship between chirality and magnetization. [ABSTRACT FROM AUTHOR]

This work follows on from studies carried out by Jiles and Atherton on magnetic hysteresis and on the magnetomechanical effect. The Jiles–Atherton equation, which models the rate of change of magnetization with respect to stress, was solved numerically in the forward and reverse directions for stress up to 90 MPa, suggesting that stressing carbon steel will cause a lasting change in the magnetization of the sample. This was confirmed experimentally by measuring the B-field in proximity to samples of C45 steel while undergoing tensile stress, with the pattern of magnetization suggesting that the magnetic domains reorient themselves in the geomagnetic field when stressing loosens their pinning. A further experiment on two samples confirms this, with the B-field around the samples showing strong changes according to their orientation in the geomagnetic field at the time of the stressing. This work has relevance to the non-destructive testing of steel structures such as pipelines, and the relevance of the experiments to this work is considered, as well as future prospects. [ABSTRACT FROM AUTHOR]

Advancements and utilization of magnetic refrigeration technology hinge on the ongoing enhancement and optimization of magnetic refrigeration material properties. Nevertheless, the intricacy of the magnetocaloric effect (MCE) mechanism has emerged as a bottleneck, constraining the progress and refinement of magnetic refrigeration materials. In this study, a classic magnetic system is chosen to investigate the mechanism of MCE across four different scales–macroscopic magnetism, micrometer‐scale magnetic domains, atomic magnetic moments, and electronic structure. It simultaneously exhibits two inverse MCEs and one direct MCE, with a working temperature span as wide as 125 K (most are <50 K) for the direct MCE. The measurements of the vibrating sample magnetometer, in situ Lorentz electron microscopy and variable‐temperature neutron powder diffraction directly reveal that the complex magnetic entropy changes arise from the magnetic domain wall pinning, the instability of Ho magnetic moments, and the spin rotation. First‐principles calculations elucidate the crucial role of strong hybridization between localized Ho and itinerant Co electrons in the spin reorientation of HoCo4Al. This study contributes significantly to comprehending the induction mechanism of the MCE and holds vital reference value for exploring new magnetic refrigeration materials and enhancing MCE performance. [ABSTRACT FROM AUTHOR]

FeSe0.4Te0.6 polycrystal bulks were synthesized using the solid‐state sintering method. We developed a novel multistep sintering process and studied the impact of the sintering cycle number. Different cycles of multistep sintering, ranging from one to four cycles were systematically arranged. It was found that the superconducting properties of the FeSe0.4Te0.6 polycrystal bulk using three cycles of sintering surpassed those of other samples, reaching a maximum of Tczero$T_{\mathrm{c}}^{{\mathrm{\ zero}}}$ = 13.4 K, Tconset$T_{\mathrm{c}}^{{\mathrm{\ onset}}}$ = 14.7 K, and a minimum of ∆Tc${T}_{\mathrm{c}}$ = 1.3 K. And the superconducting current density at 4 K reached 1.77 × 104 A/cm2, exhibiting a weak fishtail effect. At 9 K, a composite pinning effect emerged, consisting of normal point pinning and ∆κ surface pinning. The enhancement in superconductivity is attributed to improve uniformity in grain arrangement and more effective element diffusion. After multiple sintering cycles, the stacked grains exhibited increased thickness and the grain arrangement became dense. [ABSTRACT FROM AUTHOR]

The investigations of polar topological conformations have become one of the hotspots due to their multitudinous physical properties and potential applications in emerging electronic devices. However, constructing polar topologies in bulk form is exceedingly challenging. In this study, bubble domains with different polar topologies, including flux-closure and half-closure, are successfully achieved in Cu-doped (K,Na)(Nb,Ta)O 3 single crystals by elaborately adjusting the phase structure and defect dipoles. The coexistence of orthorhombic and tetragonal phases results in a flattened free energy landscape, while the presence of a high concentration of defect dipoles in local regions leads to the generation of the strong internal electric field, further modifying the energy profile. The interplay of various types of energies gives rise to the smooth rotation of the polar vectors, facilitating the formation of topological structures. These findings provide a practical method for constructing topological bubble domains in bulk materials, thereby enriching the understanding of the physical properties arising from topological structures. [ABSTRACT FROM AUTHOR]

The contact of an elastic quarter- or eighth-space is studied under the condition that the movement of the side surface of the quarter-space is constrained: It can slide freely along the plane of the side surface but its normal movement is blocked (for example, by a rigid wall). The solution of this contact problem can be easily achieved by additionally applying a mirrored load to an elastic half-space. Non-adhesive contact and the Johnson-Kendall-Roberts (JKR)-type adhesive contact between a rigid sphere and an elastic quarter-space under such a boundary condition is numerically simulated using the fast Fourier transform (FFT)-assisted boundary element method (BEM). Contacts of an elastic eighth-space are investigated using the same idea. Depending on the position of the sphere relative to the side edge, different contact behavior is observed. In the case of adhesive contact, the force of adhesion first increases with increasing the distance from the edge of the quarter-space, achieves a maximum, and decreases further to the JKR-value in large distance from the edge. The enhancement of the force of adhesion compared to the half-space-contact is associated with the pinning of the contact area at the edge. We provide the maps of the force of adhesion and their analytical approximations, as well as pressure distributions in the contact plane and inside the quarter-/eighth-space. [ABSTRACT FROM AUTHOR]

In this paper, a two-grid characteristic block-centered finite difference method is developed for solving a nonlinear Darcy-Forchheimer slightly compressible miscible displacement problem in porous media. The method is proposed for solving the nonlinear system in two steps. In the first step, the nonlinear equations are approximated on a coarse grid using the characteristic block-centered finite difference method. In the second step, the nonlinear system is linearized using Newton's method with a small positive parameter to ensure the differentiability of the nonlinear term | u | u in the Darcy-Forchheimer equation. The proposed two-grid method is rigorously analyzed, in which a priori error estimates of the velocity, pressure, concentration and its flux are provided, and the rates of convergence are O (ε + Δ t + H 3 + h 2). Finally, numerical experiments are conducted to demonstrate the effectiveness of the proposed methods by comparing the efficiency, especially in terms of CPU time. [ABSTRACT FROM AUTHOR]

High temperature oxidation of Ni–19Fe–19Cr–5Nb alloys (based on the chemical composition of Alloy718) with different Al contents were investigated to elucidate the effect of Al on oxidation kinetics and scale formation during exposure at 800 °C in air. The experimental results indicated that the oxidation kinetics decreased with increasing Al content. The beneficial effect of Al could be attributed to be a result of the formation of γ′-Ni3Al, which stabilizes γ′′-Ni3(Nb,Al) and kinetically prohibits the coarsening of γ′′-Ni3(Nb,Al) phases. Faster dissolution of finer γ′′-Ni3(Nb,Al) precipitates due to greater γ-matrix / γ′′-Ni3(Nb,Al) interface region in as-received Al-containing alloys could supply greater Nb flux for the formation of CrNbO4, which promotes the formation of an exclusive Cr2O3 scale at the initial stage of oxidation. [ABSTRACT FROM AUTHOR]

The effect of copper (II) sulfide (CuS) addition on the superconductivity of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 (CuS)x (x = 0–1.5 wt%) is reported. All samples were prepared via the co-precipitation technique. The XRD patterns revealed that the formation of Bi-2223 phase was not affected by the CuS addition. The temperature-dependent resistance measurements showed a metallic normal state behavior for all samples, with onset transition temperatures Tc onset between 109 and 118 K and zero transition temperatures Tc zero between 96 and 101 K. The intragranular and intergranular diamagnetic transition, intrinsic and coupling peak temperatures, the onset temperature of grain decoupling and the Josephson phase-locking temperature of (Bi1.6Pb0.4)Sr2Ca2Cu3O10 were not suppressed at lower CuS additions (x ≤ 0.2 wt%) but further CuS additions (x = 0.8–1.5 wt%) severely suppressed these properties. The highest Josephson current (10.82 μA) and Josephson energy coupling (22.22 meV) were exhibited by the non-added sample. The volume fraction of the grains decreased when CuS was added which indicated that the intergranular contribution was enhanced as shown by the AC susceptibility curves for all added samples. The highest transport critical current density, Jct at 40 K was for x = 0.2 wt% sample (4713 mA cm−2). The effect of internal lattice strain on the transition temperatures was also discussed. This work showed that lower addition of CuS could enhance the connectivity between the grains and enhance flux pinning. [ABSTRACT FROM AUTHOR]

This paper is concerned with the stability analysis of the stochastic strict-feedback nonlinear systems with time-varying delays on networks (SSNSTDN) via pinning control. Different from the previous literature, the new model we studied owns the non-strongly connected topology. The actual controllers are realised by back-stepping and designing virtual controllers. In particular, a novel method for constructing global Lyapunov functions is proposed,which exploits the Lyapunov function of each stochastic strict-feedback nonlinear systems with time-varying delays (SSNSTD) to construct the global Lyapunov function of SSNSTDN. Meanwhile, combining the Lyapunov method with graph theory, several sufficient conditions to guarantee the exponential stability in mean square of SSNSTDN are obtained in the form of coefficients-type criterion. Furthermore, we apply our main results to investigating the stabilisation of stochastic coupled oscillators with time-varying delays on networks and the effectiveness of proposed theories is illustrated by some numerical examples. [ABSTRACT FROM AUTHOR]

Copyright of Engineering Mechanics / Gongcheng Lixue is the property of Engineering Mechanics Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Thin films of the superconductor YBa2Cu3O7−δ (YBCO) were modified by low-energy light-ion irradiation employing collimated or focused He+ beams, and the long-term stability of irradiation-induced defects was investigated. For films irradiated with collimated beams, the resistance was measured in situ during and after irradiation and analyzed using a phenomenological model. The formation and stability of irradiation-induced defects are highly influenced by temperature. Thermal annealing experiments conducted in an Ar atmosphere at various temperatures demonstrated a decrease in resistivity and allowed us to determine diffusion coefficients and the activation energy Δ E = (0.31 ± 0.03) eV for diffusive oxygen rearrangement within the YBCO unit cell basal plane. Additionally, thin YBCO films, nanostructured by focused He+-beam irradiation into vortex pinning arrays, displayed significant commensurability effects in magnetic fields. Despite the strong modulation of defect densities in these pinning arrays, oxygen diffusion during room-temperature annealing over almost six years did not compromise the signatures of vortex matching, which remained precisely at their magnetic fields predicted by the pattern geometry. Moreover, the critical current increased substantially within the entire magnetic field range after long-term storage in dry air. These findings underscore the potential of ion irradiation in tailoring the superconducting properties of thin YBCO films. [ABSTRACT FROM AUTHOR]

Accurate air temperature measurements are essential in eddy covariance systems, not only for determining sensible heat flux but also for applying density effect corrections (DECs) to water vapor and CO2 fluxes. However, the influence of wind-induced vibrations of mounting structures on temperature fluctuations remains a subject of investigation. This study examines 30 min average temperature variances and fluxes using eddy covariance systems, combining Campbell Scientific sonic anemometers with closely co-located fine-wire thermocouples alongside LI-COR CO2 – H2O gas analyzers at multiple heights above a sagebrush ecosystem. The variances of sonic temperature after humidity corrections (Ts) and sensible heat fluxes derived from Ts are underestimated (e.g., by approximately 5 % for temperature variances and 4 % for sensible heat fluxes at 40.2 m , respectively) as compared with those measured by a fine-wire thermocouple (Tc). Spectral analysis illustrates that these underestimated variances and fluxes are caused by the lower energy levels in the Ts spectra than the Tc spectra in the low-frequency range (natural frequency < 0.02 Hz). These underestimated Ts spectra in the low-frequency range become more pronounced with increasing wind speeds, especially when wind speed exceeds 10 ms-1. Moreover, the underestimated temperature variances and fluxes cause overestimated water vapor and CO2 fluxes through DEC. Our analysis suggests that these underestimations when using Ts are likely due to wind-induced vibrations affecting the tower and mounting arms, altering the time of flight of ultrasonic signals along three sonic measurement paths. This study underscores the importance of further investigations to develop corrections for these errors. [ABSTRACT FROM AUTHOR]

The high heat input welding (HHIW) can greatly enhance the welding efficiency of the steel plates. However, coarse grains and brittle microstructures will be formed in the heat‐affected zone (HAZ) during the HHIW process, which deteriorates the toughness of HAZ. In the present study, the effect of the Ti/N ratio on the size and distribution of titanium nitride (TiN) particles, microstructures, and toughness of HAZ after HHIW of 400 kJ cm−1 is investigated for the Ca‐treated steels with different Ti/N ratios of 1.61, 3.79, and 5.00 for TN16, TN38, and TN50 steels. The TN38 steel has the highest number density of the TiN particles with the sizes between 20 and 25 nm and the highest pinning force of the particles in three steels, resulting the smallest grain sizes in its HAZ. In addition, in three steels, the TN38 steel has the main microstructure of intragranular aciculate ferrites with the highest high‐angle grain boundaries density in its HAZ, thereby obtaining the highest value of low‐temperature impact toughness of the HAZ. [ABSTRACT FROM AUTHOR]

Hypothesis: Sample-spanning particle networks are used to induce structure and a yield stress, necessary for 3D printing of porous ceramics and paints. In capillary suspensions, a small quantity of immiscible secondary fluid is incorporated into a suspension. By further adding nanoparticles with a range of hydrophobicities, the structure of the bridges and microparticle-microparticle contacts is expected to be modified, resulting in a tunable yield stress and shear moduli. Moreover, the compressibility of these samples, important in many processing and application steps, is expected to be sensitive to these changes. Experiment: The nanoparticle hydrophobicity was altered and their position relative to the microparticles and the bridges was examined using confocal microscopy where the correlation between bridge size and network structure was observed. A step-wise uniaxial compression test on the confocal was conducted to monitor the microparticle movement and structural changes between capillary suspension networks with and without nanoparticles. Findings: Our observation suggests that nanoparticles induce the formation of thin liquid films on the surface of the microparticles, mitigating contact line pinning and promoting internal liquid exchange. Additionally, nanoparticles at microparticle contact regions further diminish Hertzian contact, enhancing the capacity for rearrangement. These effects enhance microparticle movement, narrowing the bridge size distribution. Nanoparticles added to capillary suspensions : The nanoparticles either homogeneously aggregate around the microparticles or stabilize the liquid-liquid interface. These capillary nanosuspensions readily rearrange and compress, opening new opportunities for tunable design of porous ceramics, printed electronics, and low-fat spreadable chocolate. • Nanoparticles in capillary suspensions aggregate on microparticles or stabilize interfaces depending on the wettability. • Nanoparticles induce thin layers of liquid films, promoting internal liquid exchange, and reducing Hertzian contacts. • Capillary nanosuspensions demonstrate a reduction in elastic moduli and less pronounced peak in the viscous modulus. • The structures of capillary nanosuspensions rearrange more easily when subjected to compression. [ABSTRACT FROM AUTHOR]

In this work, the effect of intrinsic doping of YGBCO target density on superconducting thin films is systematically discussed. YGBCO superconducting films generated with varying densities of YGBCO targets are all pure C-axis orientated after process optimization, but the crystallinity of the films varies, and the crystalline property of the superconducting films developed from the target with the lowest density is the best. YGBCO films made with the best density objective had in-plane and out-of-plane textures of 3.5° and 1.4°, respectively. Thin film surface morphology is affected by the density of the target material; the minimal surface roughness can be as low as 5.5 nm, The critical current of YGBCO film prepared by target with the minimum density is 135 A, and the greatest current density is 5.4× 10 6 A / cm 2 . At 4.2 K and 9 T, the critical current of the thin film created with the intrinsically nailed YGBCO target can reach 338 A. This paper prepares a 530-m-long second-generation high-temperature superconducting tape with the optimized parameters. The current of the long tape is 380 A, and the current density is 4.2× 10 6 A / cm 2 . [ABSTRACT FROM AUTHOR]

The Nd-Fe-B anisotropic magnetic powders were subjected to tempering and ball milling processes. Analysis of the magnetic properties, structure, and physical phase revealed that the following: the integrated magnetic properties of the magnetic powder were the best when the tempering temperature and time were separately 650 °C and 20 min, for DOA = 0.73, Br = 6.547 kGs, Hcj = 12.255 kOe, and (BH)max = 7.117 MGOe. When the DR temperature is 860 °C, the tempering temperature is 650 °C, and the tempering time is 20 min, the ideal magnetic properties of the magnetic powder are DOA = 0.69, Br = 6.238 kGs, Hcj = 14.67 kOe, and (BH)max = 7.060 MGOe. The integrated magnetic properties of the magnetic powders were optimal when the ball milling speed, time, and doped Cu content were 350 rpm, 2 h, and 10 wt%, for DOA = 0.62, Br = 4.96 kGs, Hcj = 9.86 kOe, and (BH)max = 4.39 MGOe. The ideal tempering temperature and time can promote the diffusion of Nd-rich phase to the grain boundaries, strengthen the pinning effect on the magnetic domains, and improve the coercivity of the magnetic powder. The ideal ball milling speed and time can effectively reduce the particle size of the main phase particles of the magnetic powder and the large particles of the Nd-rich phase, so that the Nd-rich phase is uniformly distributed at the grain boundaries, to achieve the effect of de-magnetization coupling and improve the coercivity of the magnetic powder. After ball milling the magnetic powder doped with an appropriate amount of Cu powder, Cu induces the precipitation of a certain amount of Nd in the main phase of Nd2Fe14B. This Nd is uniformly distributed at the grain boundaries, achieving the effect of repairing the grain boundaries, thereby improving the coercivity of the magnetic powder. [ABSTRACT FROM AUTHOR]

We investigated the impact of annealing on the structural characteristics and superconducting critical temperature ( T c ) of the eutectic high-entropy alloy (HEA) superconductor NbScTiZr. The HEA manifests an eutectic microstructure composed of body-centered cubic (bcc) and hexagonal close-packed phases. Both the lattice parameters of the bcc phase and grain size of the eutectic structure exhibited pronounced sensitivity to variations in annealing temperature. The observed dependence of the lattice parameter on annealing temperature supports the possibility that lattice strain occurs at lower annealing temperatures. The as-cast sample demonstrated superconductivity at T c of 7.9 K, which increased to 9 K after annealing at 800 ∘ C. However, when subjected to annealing at 1000 ∘ C, T c diminishes to 8.7 K. The annealing temperature dependence of T c cannot be comprehensively elucidated based solely on the electronic density of states at the Fermi level. It is plausible that the lattice strain may influence the annealing temperature dependence of T c . Our results for the critical current density J c reveal that the self-field J c of the as-cast NbScTiZr at 2 K exceeds 10 6 A/cm 2 . [ABSTRACT FROM AUTHOR]

The Microscopy Society of America (MSA) has awarded several major awards for outstanding contributions to microscopy and microanalysis. The winners of the 2024 MSA major Society awards and MSA Fellows are highlighted in this article. The recipients include W. Gray "Jay" Jerome, J. Murray Gibson, Wu Zhou, Florian Schüder, Michael J. Zachman, Kathleen B. Reuter, Ilke Arslan, Lou Germinario, Adam Hitchcock, Yuichi Ikuhara, Ping Lu, K. Andre Mkhoyan, Velimir R. Radmilovic, David Tomlin, and Huolin Xin. Each individual has made significant contributions to the field of microscopy and microanalysis, with expertise ranging from lipid biology to AI-powered techniques for TEM. [Extracted from the article]

Superconducting transition-edge sensors (TESs) used in X-ray and γ -ray microcalorimeters suffer degraded performance if cooled in a magnetic field B sufficient to trap flux in the sensors. We report measurements of γ -ray TESs before and after implementing measures to reduce stray B fields from sources inside and outside the cryostat. These measurements showed a correlation between anomalous features in TES current–voltage (IV) curves and degraded energy resolution. After reducing internal sources of stray B field and improving shielding against external sources, both IV curves and energy resolution improved. Finally, we placed magnetized screws with remnant fields ∼ 10 μ T near similar γ -ray TESs in a different type of detector package and observed the same effects. [ABSTRACT FROM AUTHOR]

To address the challenges associated with the fabrication of highly O2-permeable Ag membranes suitable for on-site and downsized O2 separators for large-scale industrial applications, we investigated nanocrystalline heat-resistant Ag–Cu–Al alloy thin films. Ag–1 at. pct. Al and Ag–2 at. pct. Cu–1 at. pct. Al alloy thin films with nanocrystalline structures were prepared through a reactive sputtering method employing Ar–O2 mixed gas under the condition of supplying excess O/Al flux ratio above the stoichiometric ratio of Al2O3 (> 3/2). To examine the thermal stability of the nanocrystalline Ag alloy films, heating tests were conducted at 350 °C for 1 hour and 300 °C for 1 to 1000 hours in air, and the Ag crystal grain size, nanoindentation hardness, Young's modulus, and electrical resistivity were measured. The results show that the Ag–2 at. pct. Cu–1 at. pct. Al thin film has excellent thermal stability, maintaining its nanostructure with an average grain size of 30 nm after heating at 300 °C for 1000 hours in air. The effects of the addition of 2 at. pct. Cu and the O2 partial pressures during sputtering on the thermal stability of the Ag nanocrystalline structures were discussed using model calculations. It was found that supplying excess O/Al flux ratio above the stoichiometric ratio of Al2O3 (> 3/2) during sputtering reduced the dissolved Al concentration at the Ag grain boundary to substantially zero, almost completely suppressed the Ostwald ripening of nano-sized Al2O3 particles during sputtering and long-term heating, and allowed the Al2O3 particles to maintain high pinning force. Even under the excess oxygen supply conditions of O/Al > 3/2, the 2 at. pct. Cu addition was preferred for further Ag grain refinement in terms of promoting Al2O3 nucleation at the early stage of the film deposition on the substrate due to the effect of suppressing recrystallization of the Ag matrix. [ABSTRACT FROM AUTHOR]

The biological gravitational pump (BGP) and particle injection pumps (PIPs) are significant export pathways for particulate organic carbon from the surface ocean to the interior. Part of this exported carbon fuels remineralization in the mesopelagic ocean and part is sequestered in the deep ocean. Using observations from Biogeochemical‐Argo, we characterized the seasonality and magnitude of the BGP and two PIPs: the mixed layer pump (MLP) and eddy subduction pump (ESP), in the Australian sector of the Subantarctic Zone (SAZ sector). For the first time, float‐based estimates were rigorously combined with sediment trap flux (F1000) observations from the Southern Ocean Time Series (SOTS), to investigate these pumps' relative and cumulative contributions to carbon export. The BGP exports about 28.6 g C m−2 year−1, mostly during the productive season and dominates the F1000 seasonality. The MLP exports about 7.6 g C m−2 year−1, mostly while the mixing layer seasonally shoals; the ESP sporadically exports up to 100 mg C m−2 day−1, such that these two PIPs have a short but intense impact on the F1000. The carbon transfer efficiency is 3.6% in the SOTS region. An oxygen‐based annual net community production estimate (∼50 g C m−2 year−1) further strengthens this study, and suggests the BGP and MLP make the dominant contribution to the mesopelagic carbon budget. This is representative of the broader SAZ sector in terms of the magnitude and seasonality of carbon export, the consumption of organic material in the mesopelagic, and the organic carbon sequestration in the deep sea. Key Points: The biological gravitational pump is the largest and most consistent contributor to particulate organic carbon export and sequestrationParticle injection pumps enhance the carbon sequestration intensity but with relatively short duration and low frequencyThe float‐based estimates of carbon export agree well with sediment trap records and help to close the mesopelagic carbon budget [ABSTRACT FROM AUTHOR]

α-Sn, generally known as gray tin, has attracted significant scientific interest due to its potential to host novel topological phases. Studying the transport properties of α-Sn thin films grown on the InSb substrate has been challenging, as the InSb substrate also significantly contributes to the transport properties. In this article, we report a novel approach to epitaxially grow α-Sn thin films on an InSb substrate with a resistive buffer layer of CdTe. Thin films of α−Sn1−xGex (x = 0, 0.025) alloy of 15 nm thickness have been grown using molecular beam epitaxy. The high quality of the samples has been determined through high-resolution x-ray diffraction. The CdTe buffer layer has high resistance and acts as an insulating virtual substrate, which significantly suppresses contribution from InSb. Magnetotransport measurements show clear Shubnikov–de Hass oscillations in α−Sn1−xGex (x = 0, 0.025) thin films. A change in oscillation frequency is observed upon alloying with Ge, implying a modification in the electronic structure and demonstrating the effectiveness of the CdTe buffer layer approach. This work provides a new approach that enables the electronic transport characterization of the α−Sn1−xGex alloy system, which enables the study of the topological quantum states using electronic transport and their device applications. [ABSTRACT FROM AUTHOR]

This research investigates the impact of unique spherical ball shoulder enhancement tool pin configurations on the friction stir welding (FSW) of AA2219 aluminum alloy under various parameters. FSW was performed using three different pin shapes: square, hexagonal, and octagonal. Testing samples were prepared using an L9 orthogonal array layout with varying welding parameters. The material behavior in the three distinct weld zones was evaluated for each pin configuration. Results indicated superior microhardness values in the heat-affected zone (HAZ) and thermo-mechanically affected zone (TMAZ) compared to the weld nugget zone. Elemental composition analysis of the TMAZ revealed significant differences, highlighting the influence of thermal stress and material behavior due to the tool pin and shoulder configuration. The square-headed tool demonstrated improved tensile strength and microhardness. Optimal welding performance was achieved with a spindle speed of 1000 RPM, a travel speed of 25 mm/min, and a tilt angle of 3°. Variations in Cu content in the TMAZ and HAZ underscored localized modifications within the material structure, driven by the spherical ball spinning effects on the shoulder. Tensile tests showed that welds made with the square pin consistently exhibited higher tensile strength compared to those made with hexagonal and octagonal pins. [ABSTRACT FROM AUTHOR]

We have developed and optimized two categories of spin-ransfer torque magnetic tunnel junctions (STT-MTJs) that exhibit a high tunnel magnetoresistance ratio, low critical current, high outputpower in the micro-watt range, and auto-oscillation behavior. These characteristics demonstrate the potential of STT-MTJs for low-power, high-speed, and reliable spintronic applications, including magnetic memory, logic, and signal processing. The only distinguishing factor between the two categories, denoted as A-MTJs and B-MTJs, is the composition of their free layers, two CoFeB/0.21 Ta/6 CoFeSiB for A-MTJs and two CoFeB/0.21 Ta/7 NiFe for B-MTJs. Our study reveals that B-MTJs exhibit lower critical currents for auto-oscillation than A-MTJs. We found that both stacks have comparable saturation magnetization and anisotropy field, suggesting that the difference in auto-oscillation behavior is due to the higher damping of A-MTJs compared to B-MTJs. To verify this hypothesis, we employed the all-optical time-resolved magneto-optical Kerr effect technique, which confirmed that STT-MTJs with lower damping exhibited auto-oscillation at lower critical current values. Additionally, our study aimed to optimize the STT-MTJ performance by investigating the impact of the capping layer on the device's response to electronic and optical stimuli. [ABSTRACT FROM AUTHOR]

We demonstrate nonreciprocal critical current in 65 nm thick polycrystalline and epitaxial Nb thin films patterned into tracks. The nonreciprocal behavior gives a supercurrent diode effect, where the current passed in one direction is a supercurrent and the other direction is a normal state (resistive) current. We attribute fabrication artifacts to creating the supercurrent diode effect in our tracks. We study the variation of the diode effect with temperature and the magnetic field and find a dependence with the width of the Nb tracks from 2 to 10 μ m. For both polycrystalline and epitaxial samples, we find that tracks of width 4 μ m provide the largest supercurrent diode efficiency of up to ≈ 30 % , with the effect reducing or disappearing in the widest tracks of 10 μ m. We propose a model based on the limiting contributions to the critical current density to explain the track width dependence of the induced supercurrent diode effect. It is anticipated that the supercurrent diode will become a ubiquitous component of the superconducting computer. [ABSTRACT FROM AUTHOR]

High-flux capable semiconductor x-ray detectors are essential in various applications, but the detrimental effects of detector polarization limit their use in many cases. Here, we studied the polarization of perovskite CsPbBr3 semiconductor detectors using ultrahigh flux synchrotron x rays (106–1012 photons s−1 mm−2 at 58.61 keV). The CsPbBr3 detectors did not show immediate polarization prominently until a flux higher than 1010 photons s−1 mm−2. Using the pump-and-probe technique, we visualized the spatial and temporal effects of polarization. The polarized region, represented by reduced photocurrent, extended beyond the area under direct irradiation, and the reduced photocurrent persisted after potential de-polarization treatments. We found that stronger applied electric fields and fewer carrier traps can mitigate polarization, represented by less photocurrent deficit. By examining the detectors' current response under controlled ambient light, low, and high-flux x rays, we studied the trap filling and release behavior of CsPbBr3. We discovered that the polarization is caused by partial detector damage due to deep defects generated by ultrahigh flux x-ray irradiation. Our work provides insight into CsPbBr3 polarization under extremely intense x-ray radiation and shows that reducing crystal defects and increasing detector bias voltage are effective solutions. [ABSTRACT FROM AUTHOR]

The vibrational density of states of glasses is considerably different from that of crystals. In particular, there exist spatially localized vibrational modes in glasses. The density of states of these non-phononic modes has been observed to follow g(ω) ∝ ω4, where ω is the frequency. However, in two-dimensional systems, the abundance of phonons makes it difficult to accurately determine this non-phononic density of states because they are strongly coupled to non-phononic modes and yield strong system-size and preparation-protocol dependencies. In this article, we utilize the random pinning method to suppress phonons and disentangle their coupling with non-phononic modes and successfully calculate their density of states as g(ω) ∝ ω4. We also study their localization properties and confirm that low-frequency non-phononic modes in pinned systems are truly localized without far-field contributions. We finally discuss the excess density of states over the Debye value that results from the hybridization of phonons and non-phononic modes. [ABSTRACT FROM AUTHOR]

Fe(Se/Te) family compounds are very important among iron-based superconductors. To explore the modification of their physical properties, Li-doped FeSe 0. 5 Te 0. 5 polycrystalline samples were prepared by using sintering method with metal Li as the dopant. X-ray diffraction (XRD) and Raman scattering indicated that the lattice parameter c and Raman peaks change systematically with increasing Li content, suggesting Li atoms have entered the lattice. Magnetization and electrical transport measurements showed the type-II superconductor behavior. The upper critical field increased with increasing Li doping concentration, while the coherence length decreased with increasing dopant concentration. Li-doping generally improved the superconductivity, including the uniformity of superconducting contents. The thermally activated flux-flow (TAFF) activation energy also increased with increasing dopant concentration. The critical current densities were measured and the flux pinning mechanism and its change with doping were analyzed. [ABSTRACT FROM AUTHOR]

The second generation (2G) high-temperature superconducting (HTS) REBCO tape and the HTS cable made by the REBCO company are considered to be alternative materials for future superconducting magnet design due to their exceptional performance. The twisted stacked-tape slotted-core (TSSC) cable-in-conduit-conductor cable, which is one of the crucial layout structures in HTS cables, has been extensively studied by numerous research groups over the years. In this paper, a 3D finite element model of the TSSC HTS cable under bending and axial tensile loads is established using the bilinear isotropic hardening model in COMSOL commercial finite element software. The mechanical behavior of the TSSC cable under bending and axial tensile loads, as well as the evolution process of overall cable performance and critical current of individual tapes inside slots, are revealed by conducting mechanical analysis and using an empirical fitting formula between the critical current density of the 2G HTS tapes and axial strain. Furthermore, optimization engineering suggestions for its structure are provided, such as reducing the twist pitch, decreasing the tape width, increasing the number of tapes, reducing the slot width while avoiding direct contact between tapes and slot walls, increasing the number of slots, increasing diameter of diversion trench and inner diameter of helical core under predominant bending loads. In the case of axial tensile loads, the aforementioned suggestions are also applicable except for the inner and outer diameters of the helical core. The critical current performance can be enhanced by augmenting the outer diameter of the helical core in this case. However, it is almost unaffected by the inner diameter of the helical core. [ABSTRACT FROM AUTHOR]

The exchange stiffness constant is recognized as one of the fundamental properties of magnetic materials, though its accurate experimental determination remains a particular challenge. In thin films, resonance measurements exploiting perpendicular standing spin waves (PSSWs) are increasingly used to extract this parameter, typically through a determination of the first-order PSSW mode. Here, we present a systematic study of multiple PSSW modes in NiFe films, where both the sample thickness and the cap layer material are varied. The results show that a simple analysis based on the Kittel rigid pinning model yields an exchange stiffness constant that varies with thickness, mode number, and capping layer material. This finding is clearly inconsistent with physical expectation that the exchange stiffness constant of a material is single valued for a particular set of thermodynamic conditions. Using a more general exchange boundary condition, we show, through a comprehensive set of micromagnetic simulations, that a dynamic pinning mechanism originally proposed by Wigen is able to reproduce the experimental results using a single value of Aex. Our findings support the utility of short wavelength, higher order PSSWs to determine the Aex of thin films and show that the value of Aex obtained has a weak dependency on the material immediately adjacent to the magnetic layer. [ABSTRACT FROM AUTHOR]

In this work, thin films of ruthenium-doped and cerium-doped yttrium iron garnet were deposited on silicon using solgel chemistry. Doped YIG could be produced in phase pure form up to a precursor stoichiometry of Y3Ru0.1Fe4.9O12 and Ce0.7Y2.3Fe5O12. Both dopants significantly increase the coercivity and anisotropy field of the materials either due to domain wall pinning or increased spin–orbit coupling from the dopant. To delineate these two effects, the dynamic magnetic properties were studied using strip line ferromagnetic resonance (FMR). The FMR linewidth was separated into intrinsic loss and inhomogeneous line broadening. Inhomogeneous line broadening was found to dominate the magnetic losses in all the films likely due to magnon scattering off grain boundaries, but the Gilbert damping remained fairly low. By comparing the two dopants, it was found that Gilbert damping increased more in Ce:YIG films than in Ru:YIG films. This finding was corroborated by changes in the anisotropy field of the films, indicating a larger contribution from spin–orbit coupling from cerium than from ruthenium. Surprisingly, while magnetic loss globally increased with higher substitution, adding a small amount of dopant actually reduced the inhomogeneous line broadening in both sets of films. This was corroborated by crystallite size. The damping in Ru:YIG also decreased with a small amount of the dopant, which has been predicted by Kittel for doped garnets. Thus, it follows that there is an ideal doping regime where solgel YIG can be doped at low levels without increasing magnetic loss. [ABSTRACT FROM AUTHOR]

Lithium‐carbon dioxide batteries (LCBs) require a thick cathode electrode to fulfill their theoretical energy density and high areal capacity (mAh cm−2). However, understanding the design of thick porous electrodes in LCBs is challenging because of the complexity of coupled multispecies transport. Herein, a link is established between the microscopic behaviors of thick electrodes and macroscopic electrochemical performance through a spatio‐temporal resolution technique, filling the gap in knowledge on the degradation mechanism of thick electrodes. Surprisingly, the worst utilization site with the least product deposition is in the central part of the electrode rather than the traditionally presumed separator face. The secondary structure and reaction pathway of solid products exhibit a clear tendency toward spatial growth (on the electrode surface or in the interior). Combined with quantitative modeling, a critical current density shifting the dominance is found from CO2 to Li+ ions, thereby reversing the gradient of the product distribution. Finally, a hotspot map of failure mechanisms with different operating protocols is provided, serving as a guideline for the future design of thick electrodes. This work breaks the knowledge of multi‐field coupling within porous thick electrodes and can be extended to advanced Na (Li)‐CO2 (O2) battery design. [ABSTRACT FROM AUTHOR]

Asymmetric‐type UV photodetectors have attracted extensive interest for their applications in modern optoelectronics. Conventional fabrication approaches for asymmetric metal contacts typically cause damage at the metal‐semiconductor interface, leading to Fermi level pinning and further limiting barrier height adjustability and functionality. Herein, for the first time, van der Waals (vdW) asymmetric metal contact on wide bandgap semiconductor gallium‐nitride (GaN) is successfully fabricated and achieve the mitigation of Fermi level pinning effect through the formation of a damage‐free metal‐semiconductor interface. Scanning transmission electron microscopy reveals an atomically clean and sharp interface with a distinct vdW gap between the semiconductor and metal electrode. More importantly, the absence of interface damage effectively suppresses charge recombination and results in substantial enhancement in photoresponse characteristics, demonstrating an increased responsivity from 1.8 to 56.7 A W−1 along with a significantly improved response/recovery time from 545/115 to 420/20 ms and an ultralow dark current at the picoampere‐level compared to that of the photodetector with electrodes fabricated with traditional e‐beam evaporated technique. Such simultaneously enhanced responsivity and response speed overcome the responsivity‐speed trade‐off in asymmetric photodetectors and mark a milestone in integrating asymmetric metal contacts with semiconductors through a non‐destructive manner, offering unparalleled opportunities for developing high‐performance asymmetric optoelectronic systems. [ABSTRACT FROM AUTHOR]

A superconducting quantum magnetometer for high-sensitivity applications has been developed by exploiting the flux focusing of the superconducting loop. Unlike conventional dc SQUID magnetometers that use a superconducting flux transformer or a multiloop design, in this case, a very simple design has been employed. It consists of a bare dc SQUID with a large washer-shaped superconducting ring in order to guarantee a magnetic field sensitivity BΦ less than one nT/Φ0. The degradation of the characteristics of the device due to an inevitable high value of the inductance parameter βL was successfully compensated by damping the inductance of the dc SQUID. The size of the magnetometer, coinciding with that of the washer, is 5 × 5 mm2 and the spectral density of the magnetic field noise is 8 fT/√Hz with a low frequency noise knee of two Hz. The excellent performance of this simple magnetometer makes it usable for all high-sensitivity applications including magnetoencephalography. [ABSTRACT FROM AUTHOR]