Recently, the 4d transition-metal oxide RuO2 has attracted significant interest as a candidate altermagnet. However, its magnetic ground state remains controversial, as spin-transport signatures of spin-splitting torque conflict with spectroscopic evidence regarding long-range magnetic order. Using exchange bias as a local probe, we show that antiferromagnetism in RuO2 is very fragile but can be stabilized by the presence of oxygen vacancies (Vo). In epitaxial RuO2(t)/La0.5Sr0.5CoO3 bilayers, the exchange bias field exhibits an anomalous monotonic rise with the decrease of RuO2 thickness, while x-ray absorption spectra reveal the concurrent reduction in Ru valence state (i.e., increasing in Vo content) toward the interface. Further oxygen annealing has almost extinguished the exchange bias effect in all samples, directly linking the Vo density to the antiferromagnetism strength of RuO2. Density-functional calculations confirm that oxygen vacancies, regardless of crystallographic site, enlarge the antiferromagnetism-to-paramagnetism energy difference by up to one order of magnitude, and thus stabilize the antiferromagnetic state of RuO2. These results reconcile prior disparate reports, establishing vacancies as the dominant control parameter for RuO2 magnetism, and providing a practical route for engineering robust altermagnetic order in RuO2 thin-film devices.

Kagome magnets are of growing interest due to their topological electronic structures and unconventional magnetic behavior. Here, we report on the anomalous Hall effect (AHE) in the kagome ferromagnet MgMn6Sn6, which has a Curie temperature of similar to 290 K and an in-plane easy magnetization axis. Magnetotransport measurements show a positive magnetoresistance (MR) below 50 K, which becomes negative at higher temperatures. An intrinsic anomalous Hall conductivity of 114 S & sdot;cm-1 is observed in MgMn6Sn6 single crystals, consistent with ab initio calculations. Moreover, theoretical predictions indicate that shifting the Fermi level (EF) upward by similar to 70 meV could enhance the AHE to similar to 528 S & sdot;cm-1. These results position MgMn6Sn6 as a promising and tunable platform for exploring topological magnetism and related electronic phenomena.

Mitigating irreversible reverse-bias-induced perovskite degradation is paramount for the commercial deployment of perovskite solar modules, especially ensuring their reliability under partial shading scenarios. In n-i-p perovskite solar cells (PSCs), perovskite decomposition under reverse-bias involves the initial iodide re-distribution, followed by its oxidation and subsequent ultraviolet (UV) activation into iodine radicals, finally triggering the degradation within the perovskite. This work presents a delicate iodine chelation engineering to directly restrain this failure mechanism by incorporating a tailored β-cyclodextrin sulfated sodium salt (S-β-CD) at the critical SnO2/perovskite buried interface. This iodine chelating agent simultaneously sequesters the reactive iodine species from perovskites and provides the intrinsic UV-protection at the front side, to interrupt the photolysis cascade, which significantly enhances the reverse-bias robustness of PSCs. We demonstrate an outstanding operational stability after the reverse-bias precondition (T80 = ~ 1000 h, ISOS-L-3), and more encouragingly, deliver a superior cyclic lifetime under the periodic reverse-bias and light soaking stress (T85 = ~ 1600 h, ISOS-V-1). This strategy offers a significant leap towards the reverse-bias reliability required for solar module applications in the real world.

As the preferred material for plasma-facing components in future fusion test reactors, tungsten plays a critical role in ensuring the safe and stable operation of fusion reactors on the first wall of blankets and divertor targets. This paper aims to explore advanced manufacturing methods for pure tungsten and analyze the feasibility of applying additive manufacturing technology in nuclear fusion. Pure tungsten components were fabricated using powder bed fusion electron beam (PBF-EB), followed by annealing heat treatment in this work. The evolution of microstructure and mechanical properties at different annealing temperatures was investigated. Results revealed a distinct polyhedral equiaxed grain structure, with average grain size initially decreasing and then increasing as annealing temperature rose. Optimal performance was achieved at 1100 degrees C, with a density of 99.5%, Vickers hardness of 406 HV0.3, and compressive strength of 1961 MPa. Compared to untreated specimens, these properties showed substantial improvement. The findings provide guidance for developing properties of other refractory materials and improve the application of additive manufacturing in plasma-faced material fabrication.

Achieving reversible ferroic control over distinct compensated magnetic states is of fundamental importance for developing reconfigurable spintronic functionalities, yet remains a nontrivial challenge. Here we predict that layered hybrid-improper multiferroics provide a broadly applicable platform for such interconversion in the monolayer or few-layer limit. Using monolayer K3Mn2Cl7 as a representative example, whose bulk multiferroicity has been experimentally established, we show that its magnetic ground state is an insulating compensated magnet with in-plane ferroelectric polarization, and that ferroic control can drive reversible multiferroic phase transitions among multiple types of compensated magnets. The (anti)ferroelectric states here retain spin degeneracy in the nonrelativistic limit but acquire full-space persistent spin texture and transport responses. Interestingly, both ferroelectric and antiferroelectric states exhibit sign-reversible Hall transport without exchange splitting reversal found in conventional compensated magnets, revealing an unexplored form of magnetoelectric coupling. These results establish layered hybrid-improper multiferroics as promising building blocks for programmable spintronics.

Vicinal substrates drive step-flow growth in NiCo 2 O 4 , suppressing surface Ni segregation and yielding a uniform magnetic film with strongly enhanced coercivity and robust AHE response.

Series of layer-by-layer organic photovoltaics (LOPVs) were constructed with polymer D18 as donor and small molecule L8-BO with self-dissociation characteristics as acceptor. The high hole mobility and good crystallinity semiconductor C8-BTBT was deliberately incorporated into the D18 and L8-BO layers for optimizing the performance of LOPVs. The power conversion efficiency (PCE) of LOPVs can be increased from 19.10% to 20.11% by incorporating 0.5 wt% C8-BTBT in D18 layer and 0.05 wt% C8-BTBT in L8-BO layer. The PCE improvement benefits from the synergistic enhancement of short circuit current density of 27.56 mA cm-2 and fill factor of 80.10%. The incorporation of C8-BTBT in L8-BO layer can provide efficient transport channels for holes generated from L8-BO exciton self-dissociation. Introducing C8-BTBT in D18 layer can facilitate holes transport owing to its high hole mobility relative to that of D18. The interdiffusion between the D18 and L8-BO layers can be enhanced by incorporating highly crystalline C8-BTBT, facilitating exciton dissociation through enlarged donor/acceptor interfaces, as confirmed from neutron reflectivity measurements. This work indicates that incorporating high hole mobility material with good crystallinity into donor and acceptor layers is an effective strategy for achieving high-performance LOPVs.

Ferrimagnetic spinel oxides with high Curie temperature and perpendicular magnetic anisotropy are attractive for spintronic memory applications, yet optimizing their coercivity and thermal stability for robust device operation remains a challenge. Here, we report a substrate engineering approach that substantially improves the magnetic properties of epitaxial NiCo2O4 (NCO) films. On conventional flat MgAl2O4 (001) substrates, NCO films exhibit a coercivity of only similar to 50 Oe at 14 nm thickness at 300 K and suffer from rapid performance degradation under high current density. We identify surface Ni segregation as the underlying cause through polarized neutron reflectometry, which reveals a similar to 15 & Aring; magnetically inhomogeneous surface layer, and X-ray photoelectron spectroscopy depth profiling, which quantifies 4.1% excess Ni at the surface relative to stoichiometric composition. By introducing 3 degrees miscut vicinal substrates, we induce step-flow growth that kinetically suppresses cation segregation. The resulting films show a coercivity of similar to 150 Oe at 14 nm at 300 K and achieve a >5-fold enhancement (similar to 260 Oe vs. similar to 50 Oe) in 7 nm ultrathin films at 300 K, which also exhibit the largest anomalous Hall resistance favorable for device readout. Critically, the optimized films maintain square hysteresis loops under current densities up to 2000 & micro;A, whereas flat-substrate films exhibit nearly complete magnetic collapse under the same conditions. Temperature-dependent anomalous Hall effect scaling analysis reveals that the chemically uniform films exhibit a finite scattering-independent Hall conductivity component, sigma((0))(xy) = 24.3 Omega(-1) cm(-1), consistent with the recovery of the intrinsic Berry-phase contribution to anomalous Hall transport. These results demonstrate that controlling epitaxial growth kinetics through substrate engineering provides an effective route to high-coercivity oxide films for spintronic device applications.

The surface mobility of polymers is generally higher than that of the bulk (called the free surface effect), which is of fundamental and practical interest, affecting physical properties of nanoconfined polymer materials. Hence, understanding the origin of the free surface effect is essential to adjusting the physical performance (including surface properties) of nanoconfined polymers. Herein, the surface dynamics of star-shaped polystyrene with different numbers of arms (f) along with M arm = 57 kg/mol for each arm and the mechanism about its f dependence were investigated. The surface T g was observed to increase from 324 to 371 K with increasing f from 4 to 64, which was almost equal to its bulk T g when f is above 32. According to the experimental results from density distribution of the film surface via XRR and deuterium oxide vapor diffusion via neutron reflectivity, a diminished free surface effect with increasing f was attributed to an increase in surface density (the low free volume) and narrow free volume distribution on the surface, which resulted from both soft-colloid-like behavior and reduced fragility with larger f. Because of low levels of packing frustration, the chain packing efficiency on the free surface of low fragile polymers was enhanced during film formation. This study reveals directly the relationship between the free surface effect and surface density resulting from both the dynamic fragility index and the number of arms in star polystyrene.

Interface-induced magnetic skyrmions, frequently observed in ferromagnetic/heavy metal heterostructures, hold significant promise for applications in spintronic devices. Recent studies have also revealed the presence of skyrmions and the associated topological Hall effect in perovskite oxide heterostructures exhibiting strong spin-orbit coupling. The rich electron correlations and diverse physical properties inherent to perovskite oxides not only enable effective approaches for manipulating skyrmions but also open avenues for multifunctional applications. In this work, we report the topological Hall effect and potential formation of magnetic skyrmions in La0.7Sr0.3MnO3/SrIrO3 3d/5d perovskite heterostructures, driven by the interplay among exchange interaction, magnetic anisotropy, and interfacial Dzyaloshinskii-Moriya interactions. We demonstrate that the thickness of the SrIrO3 layer serves as a key parameter controlling the emergence of the topological Hall signal, mediated through the modulation of magnetic anisotropy energy via interfacial oxygen octahedral tilting. This conclusion is supported by comprehensive investigations of the interfacial microstructure, orbital states, and spin textures. Our findings highlight manganite/iridate heterostructures as a versatile oxide platform for the creation and tuning of non-collinear magnetic structures.

Purpose-The purpose of this paper is to develop extreme marine corrosion-resistant coatings and to fabricate TiZrNbTaMoW refractory high-entropy alloy thin films and clarify the effect of sputtering power. Design/methodology/approach-TiZrNbTaMoW refractory high-entropy alloy thin films were fabricated by DC magnetron sputtering. The influence of sputtering power (80/100/120 W) on their microstructure and corrosion properties was investigated. Findings-Sputtering power dominates film density, crystal orientation and composition uniformity. Uniform composition (deviation < 5%) and optimal corrosion resistance are both achieved at 100 W. Research limitations/implications-This study only focuses on sputtering power without considering other magnetron sputtering parameters. Corrosion tests are only carried out in 3.5 Wt.% NaCl solution. Practical implications-This work clarifies the sputtering power-microstructure-corrosion property relationship, offering new material and technical support for marine engineering protection. Originality/value-The regulation mechanism of sputtering power on the films was systematically investigated for the first time, providing a new research basis for refractory high-entropy alloy coatings used in marine environments.

Materials with room-temperature magnetic ordering and switchable polarization are essential for spintronic devices. Although 3 d transition metal oxides exhibit potential, their Curie temperature (TC) remains unsatisfactory, and coexistence of magnetic and polar order has not been realized in 4 d/5 d oxides. Here, through epitaxial strain and 3d-4d cation ordering engineering, a ferrimagnetic insulating state (TC ~ 623 K) is achieved in La2CoRuO6 films, coexisting with switchable short-range polar nanodomains. Atomic-scale investigations and density functional theory calculations reveal that compressive strain enhances lattice distortions. These distortions, combined with high-spin state of Co2+ ions and ordered B-site cations, significantly enhance Co-O-Ru antiferromagnetic superexchange, inducing the ferrimagnetic insulating state. Concurrently, the gradient BO6 octahedral rotations with inhomogeneous evolution trigger B-site ions' displacements, driving the formation of polar nanodomains. Our work fills the experimental gap in realizing magnetic and polar order coexistence in 4 d/5 d oxides and opens new avenues for designing high-TC multiferroics.

Unidirectional spin Hall magnetoresistance (USMR), arising from the interaction between nonequilibrium spin accumulation and magnetization, has been proposed as a simple two-terminal method for electrically detecting magnetic states in heavy-metal/ferromagnet bilayers. However, conventional spin polarization along the y direction restricts USMR to responding only to the transverse component of in-plane magnetization when a charge current is applied along the x direction. As a result, the electrical readout of longitudinal magnetic states via USMR has remained elusive. Here, we overcome this limitation by demonstrating an unconventional USMR induced by an x-polarized spin current in (001)-oriented epitaxial IrMn/FeNi bilayers, which enables electrical detection of the longitudinal magnetic state via USMR. By applying charge currents along different crystal orientations, we show that the x-polarized spin current exhibits a fourfold symmetry, consistent with the crystal mirror symmetry of (001)-oriented IrMn. This unconventional spin current further generates a large spin-orbit torque efficiency, an order of magnitude higher than that reported in antiferromagnetic Mn_{3}Pt and MnPd_{3} systems. Our Letter not only highlights the crucial role of intrinsic crystal symmetry in controlling spin polarization, but also extends the applicability of USMR to the electrical detection of longitudinal magnetization in two-terminal magnetic memory and spin-logic devices.

Clarifying the interconnection among material composition, magnetization and physical phenomenon is essential for the development of novel spintronic devices. This work reports a transformation in the emission mechanism of spintronic Terahertz (THz) emitters driven by structural design in HoCo multilayers. Using polarized neutron reflectometry (PNR), we directly observe a depth-resolved gradient magnetization distribution that arises from a variation of Co layer thickness. By performing magnetic-field-dependent THz emission measurements, we demonstrate that not only the external magnetic field, but also the internal composition gradient could qualitatively drive a transformation of the THz emission mechanism from ultrafast demagnetization to the anomalous Hall effect (AHE). The intensity of THz emission signal is quantitatively modulated by reversing the composition gradient direction. Our results underscore the significance of composition design in the design of broadband spintronic THz emission sources.

Electrical control of exchange bias in spintronic heterostructures typically relies on magnetic field cooling, ferromagnet reversal, or metallic antiferromagnets. Here, we report the simultaneous electrical switching of exchange bias and longitudinal resistance via pulse currents in a Pt/NiO/NiFe heterostructure. The switching direction of interfacial pinned spins is independent of the NiFe layer’s magnetization, contrasting with ferromagnet-governed scenarios. By systematically excluding thermal and Oersted-field effects, we attribute this behavior to the reversal of interfacial pinned spins driven by spin-orbit torque mediated through the antiferromagnetic insulator NiO. Supported by spin Hall magnetoresistance measurements and macro-spin simulations, these results demonstrate an insulator-mediated switching mechanism that operates without ferromagnet reversal or charge transport through the antiferromagnet. This work provides a platform for investigating interfacial spin dynamics in antiferromagnetic insulator-based heterostructures.

Water-based lubricants hold significant importance across multiple fields due to their environmental benignity, non-flammable safety, excellent thermal conductivity, and cost-effectiveness. However, modern water-based lubricants suffer from severe shortcomings in lubrication efficiency and anti-wear performance, limiting their broader applications. To address this problem, additives such as nonionic surfactants can be added into the formulations. This study investigates the adsorption behaviours of a typical group of nonionic surfactants, alkyl ethoxylates, denoted as C12Em, (m = 3, 6, 12, 23) on 304 stainless-steel surfaces and their correlation with lubrication performance. By using surface tension measurements, contact angle measurements, friction and wear tests, as well as various surface characterization techniques (such as spectroscopic ellipsometry, quartz crystal microbalance with dissipation, and neutron reflectometry), the intrinsic connection between the molecular structure of nonionic surfactants and their lubrication performance can be revealed. The results demonstrate that the balance between hydrophilic and hydrophobic segments in the molecular structure directly influences their adsorption configuration on metal surfaces, thereby exerting a significant impact on their lubrication and anti-wear performance. Specifically, nonionic surfactants with shorter ethoxylate chain lengths (EO) (e.g., C12E3) form dense bilayers, providing excellent lubrication and anti-wear effects, whereas those with longer EO chains (e.g., C12E12 and C12E23) exhibit weaker adsorption abilities and inferior lubrication performance. This research not only provides a theoretical basis for the design of high-performance, eco-friendly water-based lubricants but also propels the advancement of environmentally friendly lubricating materials.

The solid electrolyte interphase (SEI) governs key electrochemical properties in batteries. While additive-driven SEI engineering constitutes the most promising strategy for tailoring interfacial composition, the impact of specific additives on SEI's dynamic evolution remains unresolved. Herein, we performed operando neutron reflectometry (NR) to quantitatively resolve the SEI's structural dynamics under cycling conditions. Employing model additives with well-defined decomposition mechanisms, fluoroethylene carbonate (FEC) and vinylene carbonate (VC), we establish a robust operando NR framework that enables transferable mechanistic insights for emerging additive systems. Our data reveal contrasting SEI architectures: FEC produces a thin, inorganic-rich SEI (LiF-dominant) that enhances mechanical integrity and cycling stability, while VC yields a flexible organic-dominated SEI which mitigates stress-induced microcracking. These findings provide atomically resolved design principles for advanced electrolyte additives via operando interfacial analysis, advancing high-energy-density Li-ion batteries and beyond.

Two-dimensional van der Waals magnetic materials offer a promising platform for next-generation spintronic devices, yet achieving fully reversible and low-power voltage control of magnetization switching remains challenging. In this work, a quasi-nonvolatile and fully reversible electrical manipulation of perpendicular magnetic anisotropy is demonstrated in a horizontally-asymmetric Fe3GaTe2/CuInP2S6 van der Waals heterostructure at room temperature. By leveraging the in-plane migration and accumulation of Cu ions in CuInP2S6 under ultralow voltage pulses (0.9 V, ~16.66 kV/m), reversible modulation of the magnetic properties in the adjacent Fe3GaTe2 layer is achieved. Anomalous Hall effect and magneto-optical Kerr effect measurements confirm a cyclically stable modulation of the magnetic states, demonstrating a remarkably high voltage-controlled magnetic anisotropy coefficient (~1.0 × 106 fJ/V·m). Furthermore, it is demonstrated that the heterostructure, when integrated with spin-orbit torque devices, enables both voltage-controlled magnetic anisotropy and field-free switching of magnetization. This work provides a viable path toward energy-efficient two-dimensional spintronic devices. This work achieves room-temperature quasi-nonvolatile, fully reversible electrical tuning of perpendicular magnetic anisotropy in horizontally asymmetric Fe₃GaTe₂/CuInP₂S₆ heterostructures. Ultralow 0.9 V pulses (~16.66 kV/m) trigger in-plane Cu ion migration/accumulation in CuInP₂S₆ to reversibly modulate Fe₃GaTe₂ magnetism.

The recent discovery of topological structures has opened the door for exciting physics and emergent properties. Polar vortex domains and flux-closure domains in ferroelectric materials, as well as skyrmions and magnetic bubbles in ferromagnetic materials, are characterized by their small size, high stability, and excellent controllability, making them highly suitable for applications in information storage and sensing technologies. Although ferroelectricity and ferromagnetism are fundamentally antagonistic, researchers have discovered single-phase multiferroic materials (e.g., BiFeO3) and composite multiferroic materials (e.g., magnetoelectric heterostructures) that exhibit both properties. However, the coexistence of polar and magnetic topological structures within the same system has not yet been confirmed. Here, we demonstrate the coexistence of polar flux-closure domains and magnetic topological structures in PbTiO3/SrRuO3 ferroelectric/ferromagnetic superlattices systems. By manipulating the geometric characteristics of the polar topological structures, we achieve tunable magnetic topological signals. Strain distribution analysis and first-principles calculations reveal that the large strain gradients induced by lattice tilting are the primary factor influencing the Dzyaloshinskii-Moriya interaction. Finally, we demonstrated the tunability of the Hall resistivity through domain structure manipulation via electric field application. Our results demonstrate that polar and magnetic topological structures can stably coexist within the same system and exhibit potential coupling mechanisms. This provides new insights into tuning magnetic properties from the perspective of ferroelectric geometric structures.

Perovskite/silicon tandem solar cells (TSCs) have emerged as a promising technology for photovoltaic energy harvesting and have already exceeded the limits of traditional single-junction solar cells. Despite recent power conversion efficiency values nearing 35%, perovskite/silicon TSCs still exhibit a considerable efficiency deficit relative to their theoretical upper limit. Scientific and technological challenges related to the long-term operational stability and scalability must also be addressed for this technology to be commercialized. This Review provides an overview of state-of-the-art perovskite/silicon TSCs with particular attention to three key areas: efficiency, stability and scalability. The Review concludes with a critical overview of the remaining challenges and future perspectives for the further development of this technology. This Review covers the latest advances in perovskite/silicon tandem solar cells, with a focus on efficiency, stability and scalability, along with a discussion of outstanding challenges and future directions.