Negative-to-Positive Tunnel Magnetoresistance in van der Waals Fe_(3)GeTe_(2)/Cr_(2)Ge_(2)Te_(6)/Fe_(3)GeTe_(2)Junctions

The emergent van der Waals magnetic material is a promising component for spintronic devices with novel functionalities.Here,we report a transition of negative-to-positive magnetoresistance in Fe_(3)GeTe_(2)/Cr_(2)Ge_(2)Te_(6)/Fe_(3)GeTe_(2)van der Waals all-magnetic tunnel junctions with increasing the applied bias voltage.A negative magnetoresistance is observed first in Fe_(3)GeTe_(2)/Cr_(2)Ge_(2)Te_(6)/Fe_(3)GeTe_(2)tunnel junctions,where the resistance with antiparallel aligned magnetization of two Fe_(3)GeTe_(2)electrodes is lower than that with parallel alignment,which is due to the opposite spin polarizations of two Fe_(3)GeTe_(2)electrodes.With the bias voltage increasing,the spin polarization of the biased Fe_(3)GeTe_(2)electrode is changed so that the spin orientations of two Fe_(3)GeTe_(2)electrodes are the same.Our experimental observations are supported by the calculated spin-dependent density of states for Fe_(3)GeTe_(2)electrodes under a finite bias.The significantly bias voltage-dependent spin transport properties in van der Waals magnetic tunnel junctions open a promising route for designing electrical controllable spintronic devices based on van der Waals magnets.

Application of Capillary Electrophoretic On-Line Sequential Concentration Based on Micelle to Solvent Stacking

To take advantage of micelle to solvent stacking (MSS) to achieve more sensitivity enhancement with enough selectivity, the application of capillary electrophoretic online sequential concentration based on the MSS was reviewed. MSS has been coupled to sweeping FASS, FASI and normal EKI. Furthermore, multiple stacking by coupling MSS with more than one stacking method has also been reported. It is more sensitive and selective than solely used of one or two stacking methods and is very suitable for complex and trace sample analysis.

Detecting neutrinos from supernova bursts in PandaX-4T

Neutrinos from core-collapse supernovae are essential for understanding neutrino physics and stellar evolution.Dual-phase xenon dark matter detectors can be used to track explosions of galactic supernovae by detecting neutrinos through coherent elastic neutrino-nucleus scatterings.In this study,a variation of progenitor masses and explosion models are assumed to predict neutrino fluxes and spectra,which result in the number of expected neutrino events ranging from 6.6 to 13.7 at a distance of 10 kpc over a 10-s duration with negligible backgrounds at PandaX-4T.Two specialized triggering alarms for monitoring supernova burst neutrinos are built.The efficiency of detecting supernova explosions at various distances in the Milky Way is estimated.These alarms will be implemented in the real-time supernova monitoring system at PandaX-4T in the near future,which will provide supernova early warnings for the astronomical community.

Waveform simulation in PandaX-4T

Signal reconstruction through software processing is a crucial component of the background and signal models in the PandaX-4T experiment,which is a multi-tonne dark matter direct search experiment.The accuracy of signal reconstruction is influenced by various detector artifacts,including noise,dark count of photomultiplier,photoionization of impurities in the detector,and other relevant considerations.In this study,we presented a detailed description of a semi-data-driven approach designed to simulate a signal waveform.This work provides a reliable model for the efficiency and bias of the signal reconstruction in the data analysis of PandaX-4T.By comparing critical variables that relate to the temporal shape and hit pattern of the signals,we found good agreement between the simulation and data.

二维及拓扑自旋物理

第309期双清论坛“二维及拓扑自旋物理”总结了我国二维磁性和实空间拓扑自旋物态的相关研究进展,分析了进一步发展所面临的机遇与挑战,梳理了寻找高磁有序温度的新材料体系、拓扑及手性自旋物理、新颖拓扑磁结构的发现与表征技术等一系列未来主要研究方向,并探讨了科学基金资助模式与策略。论坛凝练出了二维及拓扑自旋物理研究领域未来5~10年的重大关键科学问题,主要包括:(1)二维磁性材料及其异质结构的物性研究;(2)拓扑磁学与自旋物理研究;(3)高分辨拓扑磁结构表征与多场调控研究;(4)低维自旋材料、物理与器件原理研究等。论坛基于二维及拓扑自旋物理研究领域的现状分析和未来展望,提出了进一步发展的建议。

Microwave Catalytic Depolymerization of Polyethylene Terephthalate Plastic to the Monomers

Plastic waste management has emerged as a critical environmental issue due to the exponential increase in plastic consumption worldwide.Polyethylene terephthalate(PET)is extensively used in the production of water bottles,which constitutes a significant fraction of the plastic waste.PET recycling is a challenging task due to the lack of efficient and cost-effective depolymerization methods.In this study,we developed a microwave(MW)catalytic depolymerization method for PET recycling using modified zinc oxide loaded with manganese oxide as a cocatalyst.The modified Mn_(3)O_(4)/ZnO catalyst presents high efficiency in depolymerizing PET into its monomers with only 0.4 wt% ratio of the catalyst to PET at 175℃ for 5 min,resulting in 100% conversion of PET and 88% selectivity toward bis-hydroxyethyl terephthalate monomers.It is believed that Mn_(3)O_(4)provides additional Lewis acid sites,promoting the dissociation of glycol from PET,and the MW irradiation plays a crucial role in rapidly heating the ethylene glycol and the catalyst,thereby accelerating the PET depolymerization process.In addition,the heterogeneous nature of the catalyst facilitates its easy separation from the reaction mixture for reuse,simplifying the catalyst recovery process and enabling costeffective and sustainable PET recycling.Thus,this study provides an innovative and sustainable solution for PET recycling,contributing toward the circular economy and mitigating the environmental impact of plastic waste.

Ultrafast magnetization enhancement and spin current injection in magnetic multilayers by exciting the nonmagnetic metal

A systematic investigation of spin injection behavior in Au/FM(FM=Fe and Ni)multilayers is performed using the superdiffusive spin transport theory.By exciting the nonmagnetic layer,the laser-induced hot electrons may transfer spin angular momentum into the adjacent ferromagnetic(FM)metals resulting in ultrafast demagnetization or enhancement.We find that these experimental phenomena sensitively depend on the particular interface reflectivity of hot electrons and may reconcile the different observations in the experiment.Stimulated by the ultrafast spin currents carried by the hot electrons,we propose the multilayer structures to generate highly spin-polarized currents for the development of future ultrafast spintronics devices.The spin polarization of the electric currents carried by the hot electrons can be significantly enhanced by the joint effects of bulk and interfacial spin filtering.Meanwhile,the intensity of the generated spin current can be optimized by varying the number of repeated stacking units and the thickness of each metallic layer.

Nonrelativistic and nonmagnetic terahertz-wave generation via ultrafast current control in anisotropic conductive heterostructures

Precise and ultrafast control over photo-induced charge currents across nanoscale interfaces could lead to important applications in energy harvesting,ultrafast electronics,and coherent terahertz sources.Recent studies have shown that several relativistic mechanisms,including inverse spin-Hall effect,inverse Rashba–Edelstein effect,and inverse spin-orbit-torque effect,can convert longitudinally injected spinpolarized currents from magnetic materials to transverse charge currents,thereby harnessing these currents for terahertz generation.However,these mechanisms typically require external magnetic fields and exhibit limitations in terms of spin-polarization rates and efficiencies of relativistic spin-to-charge conversion.We present a nonrelativistic and nonmagnetic mechanism that directly utilizes the photoexcited high-density charge currents across the interface.We demonstrate that the electrical anisotropy of conductive oxides RuO2 and IrO2 can effectively deflect injected charge currents to the transverse direction,resulting in efficient and broadband terahertz radiation.Importantly,this mechanism has the potential to offer much higher conversion efficiency compared to previous methods,as conductive materials with large electrical anisotropy are readily available,whereas further increasing the spin-Hall angle of heavy-metal materials would be challenging.Our findings offer exciting possibilities for directly utilizing these photoexcited high-density currents across metallic interfaces for ultrafast electronics and terahertz spectroscopy.

Determination of Double Beta Decay Half-Life of 136Xe with the PandaX-4T Natural Xenon Detector

Precise measurement of two-neutrino double beta decay(DBD)half-life is an important step for the searches of Majorana neutrinos with neutrinoless double beta decay.We report the measurement of DBD half-life of 136xe using the Pandax-4T dual-phase Time Projection Chamber(TPC)with 3.7-tonne natural xenon and the first 94.9-day physics data release.

Design and Optimization of Bionic Janus Blade in Hydraulic Torque Converter for Drag Reduction

The chief aim of the present work was to achieve drag reduction in stator blades with liquid using boundary layer control. A stator blade of hydraulic torque converter with bionic grooves in suction side and hydrophobic surface in pressure side was designed. The hydrophobic surface was created using anodic oxidation method and irregular A1203 thin films were found on the surface. They formed hierarchical structure consisting of mini porous structures and microscopic pore spaces, resulting in the hydrophobicity. The bionic groove was designed by Computational Fluids Dynamics （CFD） method. Multi-Island Genetic Algorithm （MIGA） was adopted for groove multi-objective optimization. Through optimization, the maximum drag reduction was close to 12% in oil. In addition, the drag reduction calculation was verified by closed channel experiment and ＂Tire Vortex＂ was proposed to explain the drag reduction mechanism. The bionic Janus blade could maintain its initial profile without any additional device, which had lower risk and less cost. The results are encouraging and show great potential to apply in other flow machineries.

Spintronic devices for neuromorphic computing

In the past decades,significant progress has been achieved in artificial intelligence,which is now widely applied in image recognition,big data analysis,unmanned vehicle control and other cognitive tasks[1].These applications nevertheless are highly energy consuming partly because of the mismatch between the neural-network-computing-based software im-plementation and the von Neumann architecture of present computers.One promising solution is developing neuro-morphic chips without the so-called von Neumann bottle-neck,which are suitable for performing the desired computation based on artificial neural networks(ANNs).

Description on the female spider of Sinanapis wuyi Jin &Zhang(Araneae:Anapidae)

The present paper deals with the female supplement of Sinanapis wuyi Jin ＆ Zhang, 2013 from Dawei Mountains, Hunan Province, China. Descriptions and diagnosis of Sinanapis wuyi Jin ＆ Zhang, 2013 are given. Detailed morphological characteristics and illustrations of body and copulatory organs are presented.

Index-free triangle-based graph local clustering

Motif-based graph local clustering(MGLC)is a popular method for graph mining tasks due to its various applications.However,the traditional two-phase approach of precomputing motif weights before performing local clustering loses locality and is impractical for large graphs.While some attempts have been made to address the efficiency bottleneck,there is still no applicable algorithm for large scale graphs with billions of edges.In this paper,we propose a purely local and index-free method called Index-free Triangle-based Graph Local Clustering(TGLC^(*))to solve the MGLC problem w.r.t.a triangle.TGLC^(*)directly estimates the Personalized PageRank(PPR)vector using random walks with the desired triangleweighted distribution and proposes the clustering result using a standard sweep procedure.We demonstrate TGLC^(*)’s scalability through theoretical analysis and its practical benefits through a novel visualization layout.TGLC^(*)is the first algorithm to solve the MGLC problem without precomputing the motif weight.Extensive experiments on seven real-world large-scale datasets show that TGLC^(*)is applicable and scalable for large graphs.

Antisymmetric planar Hall effect in rutile oxide films induced by the Lorentz force

The conventional Hall effect is linearly proportional to the field component or magnetization component perpendicular to a film. Despite the increasing theoretical proposals on the Hall effect to the in-plane field or magnetization in various special systems induced by the Berry curvature, such an unconventional Hall effect has only been experimentally reported in Weyl semimetals and in a heterodimensional superlattice. Here, we report an unambiguous experimental observation of the antisymmetric planar Hall effect(APHE) with respect to the in-plane magnetic field in centrosymmetric rutile RuO_(2) and IrO_(2) single-crystal films. The measured Hall resistivity is found to be linearly proportional to the component of the applied in-plane magnetic field along a particular crystal axis and to be independent of the current direction or temperature. Both the experimental observations and theoretical calculations confirm that the APHE in rutile oxide films is induced by the Lorentz force. Our findings can be generalized to ferromagnetic materials for the discovery of anomalous Hall effects and quantum anomalous Hall effects induced by in-plane magnetization. In addition to significantly expanding knowledge of the Hall effect, this work opens the door to explore new members in the Hall effect family.