Search

Abstract The dielectric performance of the pristine and the electrothermal‐aged metallised polypropylene capacitors are investigated under different magnetic fields. The energy storage capacity decreases under the magnetic field. At 12 T, the capacitance value of the pristine capacitors decreases by 8.4%–17% and that of the aged capacitors declines by 15%–20%. The dielectric loss is reduced by 2.6%–6.3%, but the equivalent series resistance shows an 8.3%–23.1% growth. The leakage conductivity increases to 202%–354%, which leads to a weakened voltage holding capacity. In addition to the effects of the magnetic fields, the impacts of ageing have also been investigated. The effects of the magnetic field and ageing on the electrical parameters of the capacitors are discussed separately. The molecular chains of the dielectric are oxidised and decomposed during the ageing process, which reduces the insulating properties of the dielectric. The magnetic field inhibits polarisation by changing the polarisation behaviour through Lorentz force and excites the electrons to enhance charge transmission.

Abstract Coherent spin waves possess immense potential in wave-based information computation, storage, and transmission with high fidelity and ultra-low energy consumption. However, despite their seminal importance for magnonic devices, there is a paucity of both structural prototypes and theoretical frameworks that regulate the spin current transmission and magnon hybridization mediated by coherent spin waves. Here, we demonstrate reconfigurable coherent spin current transmission, as well as magnon–magnon coupling, in a hybrid ferrimagnetic heterostructure comprising epitaxial Gd3Fe5O12 and Y3Fe5O12 insulators. By adjusting the compensated moment in Gd3Fe5O12, magnon–magnon coupling was achieved and engineered with pronounced anticrossings between two Kittel modes, accompanied by divergent dissipative coupling approaching the magnetic compensation temperature of Gd3Fe5O12 (T M,GdIG), which were modeled by coherent spin pumping. Remarkably, we further identified, both experimentally and theoretically, a drastic variation in the coherent spin wave-mediated spin current across T M,GdIG, which manifested as a strong dependence on the relative alignment of magnetic moments. Our findings provide significant fundamental insight into the reconfiguration of coherent spin waves and offer a new route towards constructing artificial magnonic architectures.

Abstract Non‐Hermitian Hamiltonians may still possess real eigenvalues in case of the existence of parity‐time (PT) symmetry. Exceptional points (EPs) occur at the phase transition from real to complex eigenvalues due to PT‐symmetry breaking in the parameter space. Magnonic devices use magnons to carry, transport, and process information, which have the advantages of low energy dissipation, wave‐based computing, and nonlinear data processing. The combination of PT‐symmetry and magnonics may lead to novel physics as well as unprecedented functional device applications. Recently, the research of PT‐symmetry in magnetism has developed rapidly. In this review, the theoretical predictions as well as experimental findings of PT‐symmetry in magnetism are summarized. First, a brief introduction to PT symmetry, EPs, and anti‐PT symmetry is presented. Second, the theoretical and experimental progress of magnonic PT symmetry are summarized. Third, the theoretical predictions of higher‐order EPs and anti‐PT symmetry in magnonic systems are given. Finally, the study concludes by discussing the future challenges and research prospects in magnonic PT‐symmetry, and proposals for experimental observations of magnonic higher‐order EPs and anti‐PT symmetry are suggested.

Manipulating electrical and magnetic anisotropies will stimulate multi-terminal device applications. Here, the authors discover axis dependence of current rectifications, magnetic properties and magnon modes in van der Waals multiferroic CuCrP2S6.

Abstract Growing concentration on the novel information processing technology and low‐cost, flexible materials make the spintronics and organic materials appealing for the future interdisciplinary investigations. Organic spintronics, in this context, has arisen and witnessed great advances during the past two decades owing to the continuous innovative exploitation of the charge‐contained spin polarized current. Albeit with such inspiring facts, charge‐absent spin angular momentum flow, namely pure spin currents (PSCs) are less probed in organic functional solids. In this review, the past exploring journey of PSC phenomenon in organic materials are retrospected, including non‐magnetic semiconductors and molecular magnets. Starting with the basic concepts and the generation mechanism for PSC, the representative experimental observations of PSC in the organic‐based networks are subsequently demonstrated and summarized, by accompanying explicit discussion over the propagating mechanism of net spin itself in the organic media. Finally, future perspectives on PSC in organic materials are illustrated mainly from the material point of view, including single molecule magnets, complexes for the organic ligands framework as well as the lanthanide metal complexes, organic radicals, and the emerging 2D organic magnets.

Spintronic devices based on spin orbit torque (SOT) have become the most promising pathway to the next-generation of ultralow-power nonvolatile logic and memory applications. Typical SOT-based spintronic devices consist of two functional materials: a spin source and a magnetic material. Spin source materials possess a strong spin orbit coupling, enabling efficient interconversion between charge and spin current. Magnetic materials are used to process and archive the information via the interaction between the local magnetic moment and the spin current generated from spin source. Considerable efforts have been put into the design of materials and devices in the past decades to realize the electrical control of magnetic switching. However, a number of key challenges still remain to be addressed for the practical application. In this paper, we reviewed the development of a range of novel materials for both the spin source and the magnetic functionalities, particularly the complex oxides and organic spintronic materials. We also discussed and highlighted several key issues, such as the mechanism and manipulation of SOT and the large-scale integration of SOT-based devices, which merit more attention in the future.

Objective: In order to provide scientific basis for further clarifying the species and characteristics of dominant pathogens causing guava black spot. Method: A dominant pathogen, named S1, was isolated and purified from the guava fruit infected with black spot disease, and subjected to morphology observation, pathogenicity determination, growth characteristics study and polymerase chain reaction (PCR) sequencing comparison analysis were conducted for comprehensive identification of the dominant pathogen S1. Results: According to the morphological observation, the aerial hyphae of the S1 colony were fluffy and dense, and the color was dark green or black. The spore morphology was monospore and transparent, and the size was uniform, about (6~10) μm×(6~7) μm, round or elliptical, compared with the "Fungus Identification Manual", it was preliminarily determined to belong to Phyllanthus spp., and once again inoculated to healthy guava fruits for pathogenicity determination. The results showed that S1 was the dominant pathogen causing guava black spot disease. Research on growth characteristics showed that S1 was more suitable for growth under alkaline, dark and normal temperature conditions. Moreover, S1 was identified as Phyllosticta capitalensis by the comparison of the PCR sequencing results. Conclusion: The dominant pathogen causing guava black spot disease was Phyllosticta capitalensis.

Abstract Developing a robust and flexible exchange bias (EB) system is crucial for wearable spintronic devices. In this work, large and robust EB effect is demonstrated in flexible Co/CoO thin films grown by magnetron sputtering. The obtained EB field is as large as 6172 Oe at low temperatures on a flexible substrate. Based on the atomistic spin models, the unexpectedly large EB field is explained by the decrease of ferromagnetic grain size and the increase of ferromagnetic /antiferromagnetic contact area. Furthermore, the strain‐dependent coercivity and EB effect are observed in flexible Co/CoO films. Finally, the flexible Co/CoO thin film shows no degradation (even a slight increase) of performances in all figures of merit after 500 bending cycles, indicating excellent mechanical durability. This study sheds light on Co/CoO as a robust EB material for flexible spintronics.

Due to the lack of a standard nanosecond high-voltage pulse generator for sensor calibration, a high-stability nanosecond high-voltage pulse test system was developed in terms of circuit analysis, structural design, and performance test. By establishing the equivalent circuit model of the nanosecond pulse generator, the circuit component parameters of the five-stage Marx loop and the one-stage compression steepening unit were simulated. The influence of the action performance of the steepening gap on the characteristics of output nanosecond pulse was analyzed. The nanosecond pulse test system was established through the structural design of the nanosecond pulse-generating circuit, the development of a high-performance corona-stabilized switch, and the measurement of a fast-response resistance divider made of metal oxide thin-film resistors. The nanosecond pulse test system has the capability to output a double exponential nanosecond pulse voltages in the amplitude range of 10–60 kV with a rise time of 2.3 ± 0.5 ns and a half-peak time of 23 ± 5 ns. In addition, the output pulse voltage has a high consistency and stability in the full amplitude range. The maximum relative standard deviation of the peak value is 1.517%, and the relative standard uncertainty is less than 5‰.

Inversion asymmetry imparts rich condensed matter phenomena in inorganic systems, and transmission of chirality across structural motifs is an attractive design strategy to break symmetry. Here, the authors use chiral organic cations to transfer structural chirality to inorganic layers in hybrid perovskites.

Long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) are involved in the mechanism underlying cerebral dysfunction after deep hypothermic circulatory arrest (DHCA), although the exact details have not been elucidated. To explore the expression profiles of lncRNAs and miRNAs in DHCA cerebral injury, we determined the lncRNA, miRNA and mRNA expression profiles in the cerebral cortex of DHCA and sham rats. First, a rat model of DHCA was established, and high-throughput sequencing was performed to analyze the differentially expressed RNAs (DERNAs). Then, the principal functions of the significantly deregulated genes were identified using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Expression networks (lncRNAs-miRNAs-mRNAs and transcription factors (TFs)-miRNAs-mRNAs) were also established. Finally, the expression of DERNAs was confirmed by quantitative real-time PCR (RT-qPCR). We identified 89 lncRNAs, 45 miRNAs and 59 mRNAs between the DHCA and sham groups and constructed a comprehensive competitive endogenous RNAs (ceRNAs) network. A TF-miRNA-mRNA regulatory network was also established. Finally, we predicted that Lcorl-miR-200a-3p-Ttr, BRD4-Ccl2 and Ep300-miR-200b-3p-Tmem72 may participate in the pathogenesis of DHCA cerebral injury.

Abstract Spin‐orbit torque (SOT) opens an efficient and versatile avenue for the electrical manipulation of magnetization in spintronic devices. The enhancement of SOT efficiency and reduction of power consumption are key points for the implementation of high‐performance SOT devices, which strongly rely on the spin‐orbit coupling (SOC) strength and magnetic properties of ferromagnetic/non‐magnetic heterostructures. Recently, van der Waals‐layered materials have shown appealing properties for use in efficient SOT applications. On the one hand, transition‐metal dichalcogenides, topological insulators, and graphene‐based heterostructures possess appreciable SOC strength. This feature can efficiently converse the charge current into spin current and result in large SOT. On the other hand, the newly discovered layered magnetic materials provide ultra‐thin and gate‐tunable ferromagnetic candidates for high‐performance SOT devices. In this review, the latest advancements of SOT research in various layered materials are summarized. First, a brief introduction of SOT is given. Second, SOT studies of various layered materials and heterostructures are summarized. Subsequently, progresses on SOT‐induced magnetization switching are presented. Finally, current challenges and prospects for future development are suggested.

Hybrid organic-inorganic trihalide perovskites can make remarkable optoelectronic devices but their spin characteristics are less investigated. Here Wang et al. show spin-polarized carriers injection into methylammonium lead bromide films with long lifetime and realize spin LEDs and spin valves.

At high temperatures, the insulation performance of polypropylene (PP) decreases, making it challenging to meet the application requirements of metallized film capacitors. In this paper, the dielectric performance of PP is improved by long-chain branching modification and adding different kinds of nucleating agents. The added nucleating agents are organic phosphate nucleating agent (NA-21), sorbitol nucleating agent (DMDBS), rare earth nucleating agent (WBG-Ⅱ) and acylamino nucleating agent (TMB-5). The results show that the long-chain branches promote heterogeneous nucleation and inhibit the motion of molecular chains, thereby enhancing the dielectric properties at high temperatures. Nucleating agents modulate the crystalline morphology of long-chain branched polypropylene (LCBPP), which leads to a decrease in the mean free path of carriers and an increase in trap energy level and trap density. Therefore, the conductivity is reduced and the breakdown strength is improved. Among the added nucleating agents, NA-21 showed a significant improvement in the electrical properties of LCBPP films. At 125 °C, compared with PP, the breakdown strength of the modified film is increased by 26.3%, and the energy density is increased by 66.1%. This method provides a reference for improving the dielectric properties of PP.