In-plane charged domain walls with memristive behaviour in a ferroelectric film.

Domain-wall nanoelectronics is considered to be a new paradigm for non-volatile memory and logic technologies in which domain walls, rather than domains, serve as an active element. Especially interesting are charged domain walls in ferroelectric structures, which have subnanometre thicknesses and exhibit non-trivial electronic and transport properties that are useful for various nanoelectronics applications1-3. The ability to deterministically create and manipulate charged domain walls is essential to realize their functional properties in electronic devices. Here we report a strategy for the controllable creation and manipulation of in-plane charged domain walls in BiFeO3 ferroelectric films a few nanometres thick. By using an in situ biasing technique within a scanning transmission electron microscope, an unconventional layer-by-layer switching mechanism is detected in which ferroelectric domain growth occurs in the direction parallel to an applied electric field. Based on atomically resolved electron energy-loss spectroscopy, in situ charge mapping by in-line electron holography and theoretical calculations, we show that oxygen vacancies accumulating at the charged domain walls are responsible for the domain-wall stability and motion. Voltage control of the in-plane domain-wall position within a BiFeO3 film gives rise to multiple non-volatile resistance states, thus demonstrating the key functional property of being a memristor a few unit cells thick. These results promote a better understanding of ferroelectric switching behaviour and provide a new strategy for creating unit-cell-scale devices.

Crystal Symmetry-Dependent In-Plane Hall Effect.

The Hall effect has played a vital role in unraveling the intricate properties of electron transport in solid materials. Here, we report on a crystal symmetry-dependent in-plane Hall effect (CIHE) observed in a CuPt/CoPt ferromagnetic heterostructure. Unlike the planar Hall effect (PHE), the CIHE in CuPt/CoPt strongly depends on the current flowing direction (ϕI) with respect to the crystal structure. It reaches its maximum when the current is applied along the low crystal-symmetry axes and vanishes when applied along the high crystal-symmetry axes, exhibiting an unconventional angular dependence of cos(3ϕI). Utilizing a symmetry analysis based on the Invariant Theory, we demonstrate that the CIHE can exist in magnetic crystals possessing C3v symmetry. Using a tight-binding model and realistic first-principles calculations on the metallic heterostructure, we find that the CIHE originates from the trigonal warping of the Fermi surface. Our observations highlight the critical role of crystal symmetry in generating new types of Hall effects.

Highly Efficient Spin Injection and Readout Across Van Der Waals Interface.

Spin injection, transport, and detection across the interface between a ferromagnet and a spin-carrying channel are crucial for energy-efficient spin logic devices. However, interfacial conductance mismatch, spin dephasing, and inefficient spin-to-charge conversion significantly reduce the efficiency of these processes. In this study, it is demonstrated that an all van der Waals heterostructure consisting of a ferromagnet (Fe3GeTe2) and Weyl semimetal enables a large spin readout efficiency. Specifically, a nonlocal spin readout signal of 150 mΩ and a local spin readout signal of 7.8 Ω is achieved, which reach the signal level useful for practical spintronic devices. The remarkable spin readout signal is attributed to suppressed spin dephasing channels at the vdW interfaces, long spin diffusion, and efficient charge-spin interconversion in Td-MoTe2. These findings highlight the potential of vdW heterostructures for spin Hall effect-enabled spin detection with high efficiency, opening up new possibilities for spin-orbit logic devices using vdW interfaces.

Highly efficient and fast modulation of magnetic coupling interaction in the SrCoO2.5/La0.7Ca0.3MnO3 heterostructure.

Effective manipulation of magnetic properties in transition-metal oxides is one of the crucial issues for the application of materials. Up to now, most investigations have focused on electrolyte-based ionic control, which is limited by the slow speed. In this work, the interfacial coupling of the SrCoO2.5/La0.7Ca0.3MnO3 (LCMO) bilayer is effectively modulated with fast response time. After being treated with diluted acetic acid, the bilayer changes from antiferromagnetic/ferromagnetic (AFM/FM) coupling to FM/FM coupling and the Curie temperature is also effectively increased. Meanwhile, the corresponding electric transport properties are modulated within a very short time. Combined with the structure characterization and X-ray absorption measurements, we find that the top SrCoO2.5 layer is changed from the antiferromagnetic insulator to the ferromagnetic metal phase, which is attributed to the formation of the active oxygen species due to the reaction between the protons in the acid and the SrCoO2.5 layer. The bottom LCMO layer remains unchanged during this process. The response time of the bilayer with the acid treatment method is more than an order of magnitude faster than other methods. It is expected that this acid treatment method may open more possibilities for manipulating the magnetic and electric properties in oxide-based devices.

Survey of Heterodera glycines population abundance and virulence phenotypes during 2021-2022 in Heilongjiang Province.

Soybean cyst nematode (SCN), Heterodera glycines, poses a significant threat to global soybean production. Heilongjiang, the largest soybean-producing province in China, contributes over 40% to the country's total yield. This province has much longer history of SCN infestation. To assess the current situation in Heilongjiang, we conducted a survey to determine the SCN population density and virulence phenotypes during 2021-2022 and compared the data with a previous study in 2015. A total of 377 soil samples from 48 counties representing eleven major soybean-planting regions were collected. The prevalence of SCN increased from 55.4% in 2015 to 59% in the current survey. The population densities ranged from 80 to 26,700 eggs and juveniles per 100 cm3 of soil. Virulence phenotypes were evaluated for 60 representative SCN populations using the HG type test, revealing nine different HG types. The most common virulence phenotypes were HG types 7 and 0, accounting for 56.7% and 20% of all SCN populations, respectively. The prevalence of populations with a reproductive index (FI) greater than 10% on PI548316 increased from 64.5% in 2015 to 71.7%. However, the FI on the commonly used resistance sources PI 548402 (Peking) and PI 437654 remained low at 3.3%. These findings highlight the increasing prevalence and changing virulence phenotypes of SCN in Heilongjiang. They also emphasize the importance of rotating soybean varieties with different resistance sources and urgently identifying new sources of resistance to combat SCN.

Manipulation of the Topological Ferromagnetic State in a Weyl Semimetal by Spin-Orbit Torque.

Magnetic Weyl semimetals (MWSMs) exhibit unconventional transport phenomena, such as large anomalous Hall (and Nernst) effects, which are absent in spatial inversion asymmetry WSMs. Compared with its nonmagnetic counterpart, the magnetic state of a MWSM provides an alternative way for the modulation of topology. Spin-orbit torque (SOT), as an effective means of electrically controlling the magnetic states of ferromagnets, may be used to manipulate the topological magnetic states of MWSMs. Here we confirm the MWSM state of high-quality Co2MnGa film by systematically investigating the transport measurements and demonstrating that the magnetization and topology of Co2MnGa can be electrically manipulated. The electrical and magnetic optical measurements further reveal that the current-induced SOT switches the topological magnetic state in a 180-degree manner by applying positive/negative current pulses and in a 90-degree manner by alternately applying two orthogonal current pulses. This work opens up more opportunities for spintronic applications based on topological materials.

Large Electromechanical Response in a Polycrystalline Alkali-Deficient (K,Na)NbO3 Thin Film on Silicon.

The demand for large electromechanical performance in lead-free polycrystalline piezoelectric thin films is driven by the need for compact, high-performance microelectromechanical systems (MEMS) based devices operating at low voltages. Here we significantly enhance the electromechanical response in a polycrystalline lead-free oxide thin film by utilizing lattice-defect-induced structural inhomogeneities. Unlike prior observations in mismatched epitaxial films with limited low-frequency enhancements, we achieve large electromechanical strain in a polycrystalline (K,Na)NbO3 film integrated on silicon. This is achieved by inducing self-assembled Nb-rich planar faults with a nonstoichiometric composition. The film exhibits an effective piezoelectric coefficient of 565 pm V-1 at 1 kHz, surpassing those of lead-based counterparts. Notably, lattice defect growth is substrate-independent, and the large electromechanical response is extended to even higher frequencies in a polycrystalline film. Improved properties arise from unique lattice defect morphology and frequency-dependent relaxation behavior, offering a new route to remarkable electromechanical response in polycrystalline thin films.

Coexistence of Magnon-Induced and Rashba-Induced Unidirectional Magnetoresistance in Antiferromagnets.

Unidirectional magnetoresistance (UMR) has been intensively studied in ferromagnetic systems, which is mainly induced by spin-dependent and spin-flip electron scattering. Yet, UMR in antiferromagnetic (AFM) systems has not been fully understood to date. In this work, we reported UMR in a YFeO3/Pt heterostructure where YFeO3 is a typical AFM insulator. Magnetic-field dependence and temperature dependence of transport measurements indicate that magnon dynamics and interfacial Rashba splitting are two individual origins for AFM UMR, which is consistent with the UMR theory in ferromagnetic systems. We further established a comprehensive theoretical model that incorporates micromagnetic simulation, density functional theory calculation, and the tight-binding model, which explain the observed AFM UMR phenomenon well. Our work sheds light on the intrinsic transport property of the AFM system and may facilitate the development of AFM spintronic devices.

Global integrative meta-analysis of the responses in soil organic carbon stock to biochar amendment.

Applying biochar to soil has been recognized as a promising practice of climate-smart agriculture, with considerable potential in enhancing soil organic carbon (SOC) sequestration. Previous studies showed that biochar-induced increases in SOC stock varied substantially among experiments, while the explanatory factors responsible for such variability are still not well assessed. Here, we conducted an integrative meta-analysis of the magnitude and efficiency of biochar-induced change in SOC stock, using a database including 476 field measurements at 101 sites across the globe. Biochar amendment increased SOC stock by 6.13 ± 1.62 (95% confidence interval, CI) and 7.01 ± 1.11 (95% CI) Mg C ha-1, respectively, compared to their unfertilized (R0) and mineral nitrogen (N) fertilized (Rn) references. Of which approx. 52% (R0) and 50% (Rn) were contributed directly by biochar-C input. Corresponding biochar carbon efficiencies in R0 and Rn datasets were estimated as 58.20 ± 10.37% and 65.58 ± 9.26% (95% CI), respectively. The change magnitude of SOC stock increased significantly (p < 0.01) with the increasing amount of biochar-C input, while carbon efficiency of biochar showed an opposite trend. Biochar amendment sequestered larger amounts of SOC with higher efficiency in acidic and loamy soils than in alkaline and sandy soils. Biochar amendments with higher C/N ratio caused higher SOC increase than those with lower C/N ratio. Random forest (RF) algorithm showed that accumulative biochar-C input, soil pH, and biochar C/N ratio were the three most-important factors regulating the SOC stock responses. Overall, these results suggest that applying high C/N ratio biochar in acidic soils is a recommendable agricultural practice from the perspective of enhancing organic carbon.

Strain-Driven Solid-Solid Crystal Conversion in Chiral Hybrid Pseudo-Perovskites with Paramagnetic-to-Ferromagnetic Transition.

Hybrid organic-inorganic perovskites (HOIPs) are promising stimuli-responsive materials (SPMs) owing to their molecular softness and tailorable structural dimensionality. The design of mechanically responsive HOIPs requires an in-depth understanding of how lattice strain induces intermolecular rearrangement that impacts physical properties. While chirality transfer from an organic cation to an inorganic lattice is known to influence chiral-optical properties, its effect on strain-induced phase conversion has not been explored. As opposed to achiral or racemic organic cations, chiral organic cations can potentially afford a new dimension in strain-responsive structural change. Herein, we demonstrate that mechanical strain induces a solid phase crystal conversion in chiral halide pseudo-perovskite single crystals (R/S)-(FE)2CuCl4 (FE = (4-Fluorophenyl)ethylamine) from a 0D isolated CuCl4 tetrahedral to 1D corner-sharing CuFCl5 octahedral framework via the incorporation of Cu···F interaction and N-H···F hydrogen bonding. This strain-induced crystal-to-crystal conversion involves the connection of neighboring 0D CuCl4 tetrahedra via Cu2+-Cl--Cu2+ linkages as well as the incorporation of a F-terminated organic cation as one of the X atoms in BX6 octahedra, leading to a reduced band gap and paramagnetic-to-ferromagnetic conversion. Control experiments using nonchiral or racemic perovskite analogs show the absence of such solid phase conversion. To demonstrate pressure-sensitive properties, the 0D phase is dispersed in water-soluble poly(vinyl alcohol) (PVA) polymer, which can be applied to a large-scale pressure-induced array display on fibrous Spandex substrates via a screen-printing method.

Electron Spin Decoherence Dynamics in Magnetic Manganese Hybrid Organic-Inorganic Crystals: The Effect of Lattice Dimensionality.

Organic-inorganic metal hybrids with their tailorable lattice dimensionality and intrinsic spin-splitting properties are interesting material platforms for spintronic applications. While the spin decoherence process is extensively studied in lead- and tin-based hybrids, these systems generally show short spin decoherence lifetimes, and their correlation with the lattice framework is still not well-understood. Herein, we synthesized magnetic manganese hybrid single crystals of (4-fluorobenzylamine)2MnCl4, ((R)-3-fluoropyrrolidinium)MnCl3, and (pyrrolidinium)2MnCl4, which represent a change in lattice dimensionality from 2D and 1D to 0D, and studied their spin decoherence processes using continuous-wave electron spin resonance spectroscopy. All manganese hybrids exhibit nanosecond-scale spin decoherence time τ2 dominated by the symmetry-directed spin exchange interaction strengths of Mn2+-Mn2+ pairs, which is much longer than lead- and tin-based metal hybrids. In contrast to the similar temperature variation laws of τ2 in 2D and 0D structures, which first increase and gradually drop afterward, the 1D structure presents a monotonous rise of τ2 with the temperatures, indicating the strong correlation of spin decoherence with the lattice rigidity of the inorganic framework. This is also rationalized on the basis that the spin decoherence is governed by the competitive contributions from motional narrowing (prolonging the τ2) and electron-phonon coupling interaction (shortening the τ2), both of which are thermally activated, with the difference that the former is more pronounced in rigid crystalline lattices.

Red-light receptor phytochrome B inhibits BZR1-NAC028-CAD8B signaling to negatively regulate rice resistance to sheath blight.

Phytochrome (Phy)-regulated light signalling plays important roles in plant growth, development, and stress responses. However, its function in rice defence against sheath blight disease (ShB) remains unclear. Here, we found that PhyB mutation or shade treatment promoted rice resistance to ShB, while resistance was reduced by PhyB overexpression. Further analysis showed that PhyB interacts with phytochrome-interacting factor-like 15 (PIL15), brassinazole resistant 1 (BZR1), and vascular plant one-zinc-finger 2 (VOZ2). Plants overexpressing PIL15 were more susceptible to ShB in contrast to bzr1-D-overexpressing plants compared with the wild-type, suggesting that PhyB may inhibit BZR1 to negatively regulate rice resistance to ShB. Although BZR1 is known to regulate brassinosteroid (BR) signalling, the observation that BR signalling negatively regulated resistance to ShB indicated an independent role for BZR1 in controlling rice resistance. It was also found that the BZR1 ligand NAC028 positively regulated resistance to ShB. RNA sequencing showed that cinnamyl alcohol dehydrogenase 8B (CAD8B), involved in lignin biosynthesis was upregulated in both bzr1-D- and NAC028-overexpressing plants compared with the wild-type. Yeast-one hybrid, ChIP, and transactivation assays demonstrated that BZR1 and NAC028 activate CAD8B directly. Taken together, the analyses demonstrated that PhyB-mediated light signalling inhibits the BZR1-NAC028-CAD8B pathway to regulate rice resistance to ShB.

Towards Automated Microfluidic-based Platforms: Optimizing Hydrogenation Efficiency of Nitrobenzene through π-π Interactions in Pd Nanoparticles on Covalent Organic Frameworks.

Microplatform with timed automata has been leveraged for guiding the preparation of molecules, whereas the requirement of handling expertise and sophisticated instrument is inevitable in combination with heterogeneous catalysis. Here we report a microfluidic-based autolab with open structures, called Put & Play Automated Microplatform (PPAM). It shows the efficient hydrogenation performance of palladium nanoparticles on the triphenylene-based covalent organic frameworks (Pd/TP-COFs) in which the π-π interactions of TP rings in the vicinity of Pd is optimized by easy change-over of catalyst and simple tuning of reactor geometries in PPAM. Using experiment/simulation of the Pd/TP-COFs coating (PCC) and mixing (PCM) across PPAM with different channel sizes, the turnover frequencies are 60 times the commonly used batch reactor, and aniline productivity of 8.8 g h-1 is achieved in 0.09 cm3 . This work will raise awareness about the benefits of the catalyst-loaded microplatform in future materials performance campaigns.

Responses of soil organic carbon stock to animal manure application: A new global synthesis integrating the impacts of agricultural managements and environmental conditions.

Enhancing soil organic carbon (SOC) through applying animal manure is of interest for both sustaining cereal production and mitigating greenhouse gas (GHG) emissions. Previous syntheses showed that manuring-induced SOC changes varied substantially with agricultural managements and environmental conditions, while their significance and relative importance to such variability are still largely uncertain. Here, we presented a new synthesis using an updated and balanced database integrating the manuring-induced SOC stock changes and their plausible explanatory factors in 250 observations at global 120 sites. Manure application increased SOC stock by 7.41 ± 1.14 (95% confidence interval, CI) and 8.96 ± 1.83 (95% CI) Mg C ha-1 , respectively, compared to their mineral fertilized (REF-min) and unfertilized (REF-zero) references. Of which approx. 72% and 34% were directly contributed by manure-C input, respectively. Following the IPCC (Intergovernmental Panel on Climate Change) approach, these changes corresponded to the manuring-induced SOC change factors of 1.27 ± 0.04 (95% CI) and 1.40 ± 0.08 (95% CI), respectively. Basing on a balanced database, we identified the amount of manure-C input as the most important factor to the global variations in the resultant SOC stock changes. More importantly, our integrative analysis distinguished the significance of soil properties (e.g., soil pH and initial SOC content) in regulating the efficiency of manure application in enhancing SOC stock. These results indicate that, at the similar rate, applying manure could sequestrate much more carbon in alkaline soils than in neutral and acidic soils. By integrating the impacts of agricultural managements and environmental conditions, our findings would help to develop region-specific tailor-made manure application measures in agriculture and to refine the SOC change factors for regional GHG inventories.

Characterization of Virulence Phenotypes of Heterodera glycines in Heilongjiang, Northeast China.

Knowledge about virulent phenotypes of Heterodera glycines Ichinohe, 1952 (soybean cyst nematode, SCN) is essential for breeding resistant cultivars and managing this nematode. Heilongjiang Province is the major soybean-producing region in China. SCN has been reported in 63 regions in Heilongjiang Province. To determine the prevalence and virulence of phenotypes of SCN, 112 soil samples were collected from soybean fields throughout the province in 2015. SCN was detected in 62 (55.4%) of these samples, with population densities ranging from 150 to 41,750 eggs and juveniles per 100 cm3 of soil. Eleven HG types, namely HG 0, 1.2.3.5.7, 1.2.3.7, 1.3.4.7, 1.3.7, 2, 2.5.7, 2.7, 6, 6.7, and 7, were detected. The percentages of SCN populations with female indices greater than 10 ranged from 4.8% for PI 437654 to 64.5% for PI 548316. This is the first report of seven of the HG types from Heilongjiang. These results provide guidance for breeding efforts and control strategies to combat SCN.

Unusual Hole and Electron Midgap States and Orbital Reconstructions Induced Huge Ferroelectric Tunneling Electroresistance in BaTiO3/SrTiO3.

Oxide heterostructures have attracted a lot of interest because of their rich exotic phenomena and potential applications. Recently, a greatly enhanced tunneling electroresistance (TER) of ferroelectric tunnel junctions (FTJs) has been realized in such heterostructures. However, our understanding on the electronic structure of resistance response with polarization reversal and the origin of huge TER is still lacking. Here, we report on electronic structures, particularly at the interface and surface, and the control of the spontaneous polarization of BaTiO3 films by changing the termination of a SrTiO3 substrate. Interestingly, unusual electron and hole midgap states are concurrently formed and accompanied by orbital reconstructions, which determine the ferroelectric polarization orientation in the BaTiO3/SrTiO3. Such unusual midgap states, which yield a strong electronic screening effect, reduce the ferroelectric barrier width and height, and pin the ferroelectric polarization, lead to a dramatic enhancement of the TER effect. The midgap states are also observed in BaTiO3 films on electron-doped Nb/SrTiO3 revealing its universality. Our result provides new insight into the origin of the huge TER effect and opens a new route for designing ferroelectric tunnel junction-based devices with huge TER through interface engineering.

Carbonate loss and resulting CO2 emission from croplands: From incorrect calculations to overestimated predictions.

Recently, Raza et al. (2020) reported the acidification-induced soil carbonate loss and resulting CO2 emission from Chinese croplands. Based on a series of calculations, the authors made scenario analyses on soil carbonate loss and subsequent CO2 emission, under different nitrogen (N) fertilization managements. While we agree with the authors that N-induced acidification accelerates carbonate loss from surface soil, we argue that their predictions are substantially overestimated due to several misconceptions in their calculations.

Perpendicular Magnetic Anisotropy and Dzyaloshinskii-Moriya Interaction at an Oxide/Ferromagnetic Metal Interface.

We report on the study of both perpendicular magnetic anisotropy (PMA) and Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM) interface, i.e., BaTiO_{3} (BTO)/CoFeB. Thanks to the functional properties of the BTO film and the capability to precisely control its growth, we are able to distinguish the dominant role of the oxide termination (TiO_{2} vs BaO) from the moderate effect of ferroelectric polarization in the BTO film, on the PMA and DMI at an oxide/FM interface. We find that the interfacial magnetic anisotropy energy of the BaO-BTO/CoFeB structure is 2 times larger than that of the TiO_{2}-BTO/CoFeB, while the DMI of the TiO_{2}-BTO/CoFeB interface is larger. We explain the observed phenomena by first principles calculations, which ascribe them to the different electronic states around the Fermi level at oxide/ferromagnetic metal interfaces and the different spin-flip process. This study paves the way for further investigation of the PMA and DMI at various oxide/FM structures and thus their applications in the promising field of energy-efficient devices.

Atomic-Scale Control of Magnetism at the Titanite-Manganite Interfaces.

Complex oxide thin-film heterostructures often exhibit magnetic properties different from those known for bulk constituents. This is due to the altered local structural and electronic environment at the interfaces, which affects the exchange coupling and magnetic ordering. The emergent magnetism at oxide interfaces can be controlled by ferroelectric polarization and has a strong effect on spin-dependent transport properties of oxide heterostructures, including magnetic and ferroelectric tunnel junctions. Here, using prototype La2/3Sr1/3MnO3/BaTiO3 heterostructures, we demonstrate that ferroelectric polarization of BaTiO3 controls the orbital hybridization and magnetism at heterointerfaces. We observe changes in the enhanced orbital occupancy and significant charge redistribution across the heterointerfaces, affecting the spin and orbital magnetic moments of the interfacial Mn and Ti atoms. Importantly, we find that the exchange coupling between Mn and Ti atoms across the interface is tuned by ferroelectric polarization from ferromagnetic to antiferromagnetic. Our findings provide a viable route to electrically control complex magnetic configurations at artificial multiferroic interfaces, taking a step toward low-power spintronics.

Vacancy-Induced Synaptic Behavior in 2D WS2 Nanosheet-Based Memristor for Low-Power Neuromorphic Computing.

Memristors with nonvolatile memory characteristics have been expected to open a new era for neuromorphic computing and digital logic. However, existing memristor devices based on oxygen vacancy or metal-ion conductive filament mechanisms generally have large operating currents, which are difficult to meet low-power consumption requirements. Therefore, it is very necessary to develop new materials to realize memristor devices that are different from the mechanisms of oxygen vacancy or metal-ion conductive filaments to realize low-power operation. Herein, high-performance and low-power consumption memristors based on 2D WS2 with 2H phase are demonstrated, which show fast ON (OFF) switching times of 13 ns (14 ns), low program current of 1 µA in the ON state, and SET (RESET) energy reaching the level of femtojoules. Moreover, the memristor can mimic basic biological synaptic functions. Importantly, it is proposed that the generation of sulfur and tungsten vacancies and electron hopping between vacancies are dominantly responsible for the resistance switching performance. Density functional theory calculations show that the defect states formed by sulfur and tungsten vacancies are at deep levels, which prevent charge leakage and facilitate the realization of low-power consumption for neuromorphic computing application.