Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spin...Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spintronics.Here,we elucidate the mechanism of magnetic polarity in the recently discovered polar metal Sr_(3)Co_(2)O_(7).Our first-principles calculations reveal that both the spontaneous polar displacements and the metallicity originate from charge disproportionation of Co ions.This is characterized by an inverted ligand-field splitting of the Co t_(2g) orbitals at one site,while the metallic behavior is preserved by the t_(2g) orbitals at both sites.Charge disproportionation,which originates from the on-site Hubbard U interaction,stabilizes the asymmetric phase.We thus propose that in related transition metal oxides,charge disproportionation within specific orbitals can concurrently drive metallicity and polarity,enabling strong coupling between these properties.More remarkably,this mechanism allows for the coexistence of magnetism,as evidenced in Sr_(3)Co_(2)O_(7).Our findings highlight a promising avenue for realizing polar magnetic metals and provide a new design principle for exploring multifunctional materials.展开更多
We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magneto optica...We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magneto optical traps (MOTs) and Ioffe traps can be constructed by using same wire configurations and different currents and bias fields. Furthermore, the array of double-well magnetic microtraps can be continuously evolved as an array of single-well magnetic microtraps by reducing the currents in the wires. Our study shows that our scheme can be used to realize a controllable double-layer magnetic lattice with cold atoms, to form array of Bose-Einstein condensations (BECs), or to study atom interference, and so on.展开更多
The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in im- proving capacitor performance. In this study, active carbon/Fe304-NPs nanocom...The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in im- proving capacitor performance. In this study, active carbon/Fe304-NPs nanocomposites （AC/Fe304-NPs） were synthesized using a facile hy- drothermal method and ultrasonic technique. Transmission electron micrographs （TEM） showed that Fe304 nanoparticles （Fe304-NPs） grew along the edge of AC. AC/Fe304-NPs nanocomposites were further used as an electrochemical electrode, and its electrochemical performance was tested under magnetization and non-magnetization conditions, respectively, in a three-electrode electrochemical device. Micro-magnetic field could improve the electric double-layer capacitance, reduce the charge transfer resistance, and enhance the discharge performance. The capacitance enhancement of magnetized electrode was increased by 33.1% at the current density of 1 A/g, and the energy density was improved to 15.97 Wh/kg, due to the addition of magnetic particles.展开更多
Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and cha...Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and challenging to achieve effective regulation of shielding effectiveness(SE)as well as weaken the strong EM reflection of highly conductive biomass-based carbon materials.Herein,commercial cotton pads with oriented structure were selected as carbonaceous precursor to fabricate aligned carbon networks by pyrolysis,and the EMI SE of the samples with increased temperature of 800-1000℃ can be accurately controlled in the effective range of~21.7-29.1,~27.7-37.1 and~32.7-43.3 d B with high reflection coefficient of>0.8 by changing the cross-angle between the electric-field direction of incident EM waves and the fiber-orientation direction due to the occurrence of opposite internal electric field.Moreover,the further construction of Salisbury absorber-liked double-layer structure could result in an ultralow reflection coefficient of only~0.06 but enhanced SE variation range up to~38.7-49.3 d B during the adjustment of cross-angle,possibly due to the destructive interference of EM waves in the double-layer carbon networks.This work would provide a simple and effective way for constructing high-performance biomass carbon materials with adjustable EMI shielding and ultra-low reflectivity.展开更多
This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum flu...This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum fluctuations of spins. If the anisotropy exists, there will be no acoustic energy branch in the system. The anisotropy constant, antiferromagnetic intralayer and interlayer coupling have important roles in a balance of the quantum competition.展开更多
Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigati...Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.展开更多
Soft magnetic alloys are extensively used in various power electronic devices due to their advantageous properties,including high saturation magnetic induction,low coercivity,and high permeability.In certain applicati...Soft magnetic alloys are extensively used in various power electronic devices due to their advantageous properties,including high saturation magnetic induction,low coercivity,and high permeability.In certain applications,complex-shaped components are increasingly required for performance enhancement.Additive manufacturing technique,particularly selective laser melting(SLM),has emerged as an effective method for fabricating such complex-shaped soft magnetic components.SLM,a laserbased additive manufacturing technique,employs high-power-density lasers to melt and fuse metal powders within a powder bed selectively.This approach enables rapid prototyping,precise geometrical control,and the integration of multi-material designs.This review highlights recent advancements in the application of SLM technique for the production of soft magnetic alloys,focusing on Fe-Si,Fe-Ni,Fe-Co,and amorphous alloy systems.Moreover,it explores the implementation of SLM in manufacturing processes and evaluates both the opportunities and challenges associated with SLM-based production of soft magnetic alloys.展开更多
Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabl...Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabling topological functionalities in the post-Moore era.Here we review recent progress on two-dimensional(2D)magnetism in LTMCs,emphasizing material taxonomy,intrinsic magnetic properties,and external-field controls.This review first presents a classification of LTMCs by crystal structure and chemistry—binary halides,chalcogenides,and ternary families(e.g.,MPX_(3),M_(m)X_(n)Te_(k),MnBi_(2)Te_(4))—followed by a summary of their coupling mechanisms,ordering temperatures,and dimensional effects.It then analyzes the modulation of exchange interactions,magnetic anisotropy,and topological states by electric-field gating,strain engineering,and ion intercalation,with representative experimental demonstrations.Notable advances include room-temperature ferromagnetic metals and semiconductors,observation of the quantum anomalous Hall effect(QAHE)in MnBi2Te4,and synergistic control of magnetic-topological states under multiple external stimuli.Persistent challenges involve the limited availability of intrinsic 2D magnetic semiconductors with high Curie temperatures(Tc),incomplete understanding of the microscopic couplings at interfaces and under quantum confinement,and device-level stability.We conclude by outlining opportunities that lie in the integration of multiscale characterization,first-principles theory,and cross-scale fabrication to precisely co-engineer magnetism,topology,and electronic structure,thereby advancing LTMCs toward spintronic and topological-quantum applications.展开更多
First-principles calculations and Monte Carlo simulations reveal that single-layer and double-layer VX_(2)(X=Cl,Br)can be tuned from antiferromagnetic(AFM)semiconductors to ferromagnetic(FM)state when biaxial tensile ...First-principles calculations and Monte Carlo simulations reveal that single-layer and double-layer VX_(2)(X=Cl,Br)can be tuned from antiferromagnetic(AFM)semiconductors to ferromagnetic(FM)state when biaxial tensile stress is applied.Their ground states are all T phase.The biaxial tensile stress at the phase transition point of the double-layer VX_(2) is larger than that of the single-layer VX_(2).The direct band gaps can be also manipulated by biaxial tensile stress as they increases with increasing tensile stress to a critical point and then decreases.The Neel temperature(´TN)of double-layer VX_(2) are higher than that of single-layer.As the stress increases,the TN of all materials tend to increase.The magnetic moment increases with the increase of biaxial tensile stress,and which become insensitive to stress after the phase transition points.Our research provides a method to control the electronic and magnetic properties of VX_(2) by stress,and the single-layer and double-layer VX_(2) may have potential applications in nano spintronic devices.展开更多
In this study,a multifunctional aptamer-conjugated magnetic covalent organic framework(COF)-CuO/Au nanozyme(MCOF-CuO/Au@apt)was developed as a“three-in-one”platform for dual-signal colorimetric and fluorescent detec...In this study,a multifunctional aptamer-conjugated magnetic covalent organic framework(COF)-CuO/Au nanozyme(MCOF-CuO/Au@apt)was developed as a“three-in-one”platform for dual-signal colorimetric and fluorescent detection of Vibrio parahaemolyticus.The nanozyme integrated magnetic separation,peroxidase-like catalytic activity,and specific target recognition through an aptamer-based strategy.Upon binding to V.parahaemolyticus,the catalytic oxidation of tetra-aminophenylethylene(TPE-4A)by the nanozyme was selectively inhibited,resulting in distinct colorimetric and fluorescent signals that significantly enhanced the detection accuracy and reliability.The proposed method exhibited high sensitivity,with limits of detection(LOD)of 21 and 7 CFU/mL for the colorimetric and fluorescent assays,respectively.The performance of this method was validated using real seafood samples,including Penaeus vannamei,Mytilus coruscus,and Crassostrea gigas,which showed high recovery rates(101.11%-107.30%)and excellent reproducibility.The system also demonstrated strong specificity and accuracy under various conditions,confirming its robustness and practical applicability.Collectively,this innovative platform presents a promising solution for the rapid,versatile,and sensitive detection of V.parahaemolyticus in seafood,with considerable potential to advance food safety diagnosis and on-site monitoring.展开更多
Dissimilar AZ31B magnesium alloy and DC56D steel were welded via AA1060 aluminum alloy by magnetic pulse welding.The effects of primary and secondary welding processes on the welded interface were comparatively invest...Dissimilar AZ31B magnesium alloy and DC56D steel were welded via AA1060 aluminum alloy by magnetic pulse welding.The effects of primary and secondary welding processes on the welded interface were comparatively investigated.Macroscopic morphology,microstructure,and interfacial structure of the joints were analyzed using scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer(XRD).The results show that magnetic pulse welding of dissimilar Mg/Fe metals is achieved using an Al interlayer,which acts as a bridge for deformation and diffusion.Specifically,the AZ31B/AA1060 interface exhibits a typical wavy morphology,and a transition zone exists at the joint interface,which may result in an extremely complex microstructure.The microstructure of this transition zone differs from that of AZ31B magnesium and 1060 Al alloys,and it is identified as brittle intermetallic compounds(IMCs)Al_(3)Mg_(2) and Al_(12)Mg_(17).The transition zone is mainly distributed on the Al side,with the maximum thickness of Al-side transition layer reaching approximately 13.53μm.Incomplete melting layers with varying thicknesses are observed at the primary weld interface,while micron-sized hole defects appear in the transition zone of the secondary weld interface.The AA1060/DC56D interface is mainly straight,with only a small number of discontinuous transition zones distributed intermittently along the interface.These transition zones are characterized by the presence of the brittle IMC FeAl_(3),with a maximum thickness of about 4μm.展开更多
Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of...Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of skyrmions.MnGe,as a member of the B20 family,exhibits a more complex magnetic structure compared with other materials with similar crystal structures.In this work,we successfully synthesized high-quality MnGe thin films and characterized their magnetoresistance,M-H curves,magneto-Seebeck effect,and magnetic force microscopy(MFM)images,all of which demonstrate pronounced magnetic anisotropy.Notably,the Seebeck coefficient exhibits a plateau at low magnetic fields when the magnetic field is applied in the film plane,indicating a field region in which the magnetic structure remains stable.MFM imaging further reveals magnetic transitions within the MnGe films when the magnetic field is oriented along the film plane.These findings are crucial for advancing our understanding of the magnetic ground state of MnGe and the evolution of its magnetic structure under an applied external magnetic field.展开更多
T he residual stray magnetic fields present in ferromagnetic casting slabs were investigated in this work,which result from the magnetic fields generated during the steel casting process.Existing optical detection met...T he residual stray magnetic fields present in ferromagnetic casting slabs were investigated in this work,which result from the magnetic fields generated during the steel casting process.Existing optical detection methods face challenges owing to surface oxide scales,and conventional high-precision magnetic sensors are ineffective at high temperatures.To overcome these limitations,a small coil sensor was employed to measure the residual magnetism strength in oscillation traces,using metal magnetic memory and electromagnetic induction methods,which can carry out detection without an external excitation source.Using this technology,the proposed scheme successfully detects defects at high tempe-ratures(up to 670℃)without a cooling device.The key findings include the ability to detect both surface and near-surface defects,such as cracks and oscillation marks,with an enhanced signal-to-noise ratio(SNR)of 7.2 dB after signal processing.The method’s practicality was validated in a steel mill environment,where testing on casting slabs effectively detected defects,providing a foundation for improving industrial quality control.The proposed detection scheme offers a significant advancement in nondestructive testing(NDT)for high-temperature applications,contributing to more efficient and accurate monitoring of ferromagnetic material integrity.展开更多
Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully construct...Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully constructed by coordinatively assembling the semi-rigid multidentate ligand 5-(1-carboxyethoxy)isophthalic acid(H₃CIA)with the Nheterocyclic ligands 1,4-di(4H-1,2,4-triazol-4-yl)benzene(1,4-dtb)and 1,4-di(1H-imidazol-1-yl)benzene(1,4-dib),respectively,around Co^(2+)ions.Single-crystal X-ray diffraction analysis revealed that in both complexes HU23 and HU24,the CIA^(3-)anions adopt aκ^(7)-coordination mode,bridging six Co^(2+)ions via their five carboxylate oxygen atoms and one ether oxygen atom.This linkage forms tetranuclear[Co4(μ3-OH)2]^(6+)units.These Co-oxo cluster units were interconnected by CIA^(3-)anions to assemble into 2D kgd-type structures featuring a 3,6-connected topology.The 2D layers were further connected by 1,4-dtb and 1,4-dib,resulting in 3D pillar-layered frameworks for HU23 and HU24.Notably,despite the similar configurations of 1,4-dtb and 1,4-dib,differences in their coordination spatial orientations lead to topological divergence in the 3D frameworks of HU23 and HU24.Topological analysis indicates that the frameworks of HU23 and HU24 can be simplified into a 3,10-connected net(point symbol:(4^(10).6^(3).8^(2))(4^(3))_(2))and a 3,8-connected tfz-d net(point symbol:(4^(3))_(2)((4^(6).6^(18).8^(4)))),respectively.This structural differentiation confirms the precise regulatory role of ligands on the topology of metal-organic frameworks.Moreover,the ultraviolet-visible absorption spectra confirmed that HU23 and HU24 have strong absorption capabilities for ultraviolet and visible light.According to the Kubelka-Munk method,their bandwidths were 2.15 and 2.08 eV,respectively,which are consistent with those of typical semiconductor materials.Variable-temperature magnetic susceptibility measurements(2-300 K)revealed significant antiferromagnetic coupling in both complexes,with their effective magnetic moments decreasing markedly as the temperature lowered.CCDC:2457554,HU23;2457553,HU24.展开更多
In recent years,the rising incidence of gastrointestinal(GI)cancer has triggered an urgent need for effective early intervention strategies.Traditional endoscopic techniques often cause patient discomfort,and it is di...In recent years,the rising incidence of gastrointestinal(GI)cancer has triggered an urgent need for effective early intervention strategies.Traditional endoscopic techniques often cause patient discomfort,and it is difficult to navigate deep regions of complex organ structures.This work proposes a kind of bio-inspired magnetic soft robot(BMSR)to address these challenges.The design of the BMSRs is inspired by the rolling motion of the golden wheel spider.Two six-degree-of-freedom(6-DOF)robotic arms are used,where one arm is responsible for real-time manipulation of the BMSRs,and the other is dedicated to monitoring their status.Under the actuation of an external rotating magnetic field,the BMSRs can flexibly climb on inclined surfaces at any angle,involving the inverted surface.Through the powerful output force,the BMSRs can overcome the mobility barrier induced by different human organs,including mucus,folds,and height differences of up to 8 cm.Such an exceptional mobility enables the BMSRs to deliver drugs in the targeted complex GI environment.Moreover,in combination with an endoscope,it provides real-time visual feedback for precise navigation.In vitro animal experiments validate the feasibility of BMSRs,paving a way for their usage in minimally invasive GI treatment.This work advances the potential applications of magnetic soft robots in the biomedical field.展开更多
The spin-sensitive nature of redox reactions in energy conversion systems,such as the oxygen evolution reaction(OER),has attracted increasing attention due to its potential for enhancing catalytic efficiency.Magnetic ...The spin-sensitive nature of redox reactions in energy conversion systems,such as the oxygen evolution reaction(OER),has attracted increasing attention due to its potential for enhancing catalytic efficiency.Magnetic fields(MFs)have been proposed to enhance OER performance by influencing the spin states of oxygen intermediates.However,prior study has predominantly focused on MF effects mediated by the intrinsic magnetic properties of electrocatalysts or magnetohydrodynamics.In this work,we report a universal enhancement in OER activity,achieving over 150% increase in current density under a200 mT MF across diamagnetic,paramagnetic and magnetic electrocatalysts in 1 M KOH.Through systematic investigation of MF orientation and strength,pH,applied potentials,and the use of benzoquinone radical scavenger,we demonstrate that MF-driven performance improvements arise from direct modulation of oxygen radical spin states.Specifically,MFs promote the formation of spin-triplet oxygen intermediates(↑O–O↑),a critical step for O–O bond formation,independent of the catalyst's intrinsic magnetism.However,the local magnetic environment near the catalyst surface,governed by its magnetic properties,indirectly influences radical spin dynamics by alternating the effective field experienced by intermediates.These findings redefine the role of spin manipulation in electrocatalysis,advancing understanding of MF-driven spin effects in redox reactions.展开更多
The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipo...The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipole with a shared coil between the two apertures,forming an I-shaped structure that can reduce power consumption by 50%.Because of its long length and low field strength,the development of this dual-aperture magnet faces challenges regarding its mechanical design,field measurement accuracy,and field performance.Numerical simulations were performed to better understand the Earth's field and the effect of different BH curves on field performance.The field results of the prototype are presented herein,and the field quality satisfies the requirements.The remanent field accounts for 2%of the integral field at 140 Gs,and the hysteresis effect caused an increase in field strength of approximately 0.075%after a standardization cycle of the trim coils.Research on this prototype can provide useful insights for understanding low-field dipole magnets.展开更多
The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-bas...The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.展开更多
We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate...We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate that the efficiency of the spin-orbit torque increases nearly linearly with the repetition number n,which is in excellent agreement with the spin Hall effect of the Pt_(0.75)Ti_(0.25)being essentially the only source of the observed spin-orbit torque.The perpendicular magnetic anisotropy field is also substantially enhanced by more than a factor of 2 as n increases from 1 to6.The[Pt_(0.75)Ti_(0.25)/Co-Ni multilayers/Ta]_n superlattice additionally exhibits deterministic,low-current-density magnetization switching despite the very large total layer thicknesses.The unique combination of strong spin-orbit torque,robust perpendicular magnetic anisotropy,low-current-density switching,and excellent high thermal stability makes the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice a highly compelling material candidate for ultrafast,energy-efficient,and long-data-retention spintronic technologies.展开更多
Large magnetic entropy change(△S_(M))can realize a prominent heat transformation under the magnetic field and directly strengthen the efficacy of the magnetocaloric effect,which provides a pioneering environmentally ...Large magnetic entropy change(△S_(M))can realize a prominent heat transformation under the magnetic field and directly strengthen the efficacy of the magnetocaloric effect,which provides a pioneering environmentally friendly solidstate strategy to improve refrigeration capacities and efficiencies.The second-order magnetic transition(SOMT)materials have broader△S_(M) peaks without thermal hysteresis,making them highly attractive in magnetic refrigeration,especially in the room temperature range.Here,we report a significant enhancement of△S_(M) at room temperature in single-crystal Mn_(5)Ge_(3).In this SOMT system,we realize a 60%improvement of-△S_(M)^(max) from 3.5 J/kg·K to 5.6 J/kg·K at T=300 K.This considerable enhancement of△S_(M) is achieved by intentionally introducing strain energy through high-pressure constrained deformation.Both experimental results and Monte Carlo simulations demonstrate that the enhancement of△S_(M) originates from the microscopic strain and lattice deformation induced by strain energy after deformation.This strain energy will reconstruct the energy landscape of this ferromagnetic system and enhance magnetization,resulting in a giant intensity of magnetocaloric responses.Our findings provide an approach to increase magnetic entropy change and may give fresh ideas for exploring advanced magnetocaloric materials.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.12274309 for H.-F.H.and J.-X.Y.)NERSC award (Grant No.BES-ERCAP0037158)。
文摘Strong coupling among spontaneous structural symmetric breaking,magnetism,and metallicity in an intrinsic polar magnetic metal can give rise to novel physical phenomena and holds great promise for applications in spintronics.Here,we elucidate the mechanism of magnetic polarity in the recently discovered polar metal Sr_(3)Co_(2)O_(7).Our first-principles calculations reveal that both the spontaneous polar displacements and the metallicity originate from charge disproportionation of Co ions.This is characterized by an inverted ligand-field splitting of the Co t_(2g) orbitals at one site,while the metallic behavior is preserved by the t_(2g) orbitals at both sites.Charge disproportionation,which originates from the on-site Hubbard U interaction,stabilizes the asymmetric phase.We thus propose that in related transition metal oxides,charge disproportionation within specific orbitals can concurrently drive metallicity and polarity,enabling strong coupling between these properties.More remarkably,this mechanism allows for the coexistence of magnetism,as evidenced in Sr_(3)Co_(2)O_(7).Our findings highlight a promising avenue for realizing polar magnetic metals and provide a new design principle for exploring multifunctional materials.
基金This work was supported by the National Natural Science Foundation of China (No. 10174050, 10374029, and 10434060)Shanghai Priority Academic Discipline, and the 211 Foundation of the Educational Ministry of China.
文摘We propose a novel array of controllable double-well magnetic microtraps for cold atoms by using an array of square current-carrying wires and two additional bias magnetic fields. Arrays of double layer magneto optical traps (MOTs) and Ioffe traps can be constructed by using same wire configurations and different currents and bias fields. Furthermore, the array of double-well magnetic microtraps can be continuously evolved as an array of single-well magnetic microtraps by reducing the currents in the wires. Our study shows that our scheme can be used to realize a controllable double-layer magnetic lattice with cold atoms, to form array of Bose-Einstein condensations (BECs), or to study atom interference, and so on.
基金supported by the National Natural Science Foundation of China(Grant No.21376034 and 21373025)
文摘The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in im- proving capacitor performance. In this study, active carbon/Fe304-NPs nanocomposites （AC/Fe304-NPs） were synthesized using a facile hy- drothermal method and ultrasonic technique. Transmission electron micrographs （TEM） showed that Fe304 nanoparticles （Fe304-NPs） grew along the edge of AC. AC/Fe304-NPs nanocomposites were further used as an electrochemical electrode, and its electrochemical performance was tested under magnetization and non-magnetization conditions, respectively, in a three-electrode electrochemical device. Micro-magnetic field could improve the electric double-layer capacitance, reduce the charge transfer resistance, and enhance the discharge performance. The capacitance enhancement of magnetized electrode was increased by 33.1% at the current density of 1 A/g, and the energy density was improved to 15.97 Wh/kg, due to the addition of magnetic particles.
基金financial supports from Natural Science Foundation of Ningbo(202003N4026)S&T Innovation 2025 Major Special Programme of Ningbo(2018B10054)National Natural Science Foundation of China(62001065 and 51603218)。
文摘Nowadays,carbon frameworks derived from natural biomaterials have attracted extensive attention for electromagnetic interference(EMI)shielding due to their renewability and affordability.However,it is critical and challenging to achieve effective regulation of shielding effectiveness(SE)as well as weaken the strong EM reflection of highly conductive biomass-based carbon materials.Herein,commercial cotton pads with oriented structure were selected as carbonaceous precursor to fabricate aligned carbon networks by pyrolysis,and the EMI SE of the samples with increased temperature of 800-1000℃ can be accurately controlled in the effective range of~21.7-29.1,~27.7-37.1 and~32.7-43.3 d B with high reflection coefficient of>0.8 by changing the cross-angle between the electric-field direction of incident EM waves and the fiber-orientation direction due to the occurrence of opposite internal electric field.Moreover,the further construction of Salisbury absorber-liked double-layer structure could result in an ultralow reflection coefficient of only~0.06 but enhanced SE variation range up to~38.7-49.3 d B during the adjustment of cross-angle,possibly due to the destructive interference of EM waves in the double-layer carbon networks.This work would provide a simple and effective way for constructing high-performance biomass carbon materials with adjustable EMI shielding and ultra-low reflectivity.
基金supported by the Natural Science Foundation of the Educational Department of Liaoning Province,China (Grant Nos20060638 and 2008533)
文摘This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum fluctuations of spins. If the anisotropy exists, there will be no acoustic energy branch in the system. The anisotropy constant, antiferromagnetic intralayer and interlayer coupling have important roles in a balance of the quantum competition.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074213 and 11574108)the National Key R&D Program of China(Grant No.2022YFA1403103)+2 种基金the Major Basic Program of Natural Science Foundation of Shandong Province(Grant No.ZR2021ZD01)the Natural Science Foundation of Shandong Province(Grant No.ZR2023MA082)the Project of Introduction and Cultivation for Young Innovative Talents in Colleges and Universities of Shandong Province。
文摘Two-dimensional double-layer honeycomb(DLHC)materials are known for their diverse physical properties,but superconductivity has been a notably absent characteristic in this structure.We address this gap by investigating M_(2)N_(2)(M=Nb,Ta)with DLHC structure using first-principles calculations.Our results show that M_(2)N_(2)are stable and metallic,exhibiting superconducting behavior.Specifically,Nb_(2)N_(2)and Ta_(2)N_(2)display superconducting transition temperatures of 6.8 K and 8.8 K,respectively.Their electron-phonon coupling is predominantly driven by the coupling between metal d-orbitals and low-frequency metal-dominated vibration modes.Interestingly,two compounds also exhibit non-trivial band topology.Thus,M_(2)N_(2)are promising platforms for studying the interplay between topology and superconductivity and fill the gap in superconductivity research for DLHC materials.
基金National Natural Science Foundation of China(52171191,52371198)Project of Constructing National Independent Innovation Demonstration Zones(XM2024XTGXQ05)。
文摘Soft magnetic alloys are extensively used in various power electronic devices due to their advantageous properties,including high saturation magnetic induction,low coercivity,and high permeability.In certain applications,complex-shaped components are increasingly required for performance enhancement.Additive manufacturing technique,particularly selective laser melting(SLM),has emerged as an effective method for fabricating such complex-shaped soft magnetic components.SLM,a laserbased additive manufacturing technique,employs high-power-density lasers to melt and fuse metal powders within a powder bed selectively.This approach enables rapid prototyping,precise geometrical control,and the integration of multi-material designs.This review highlights recent advancements in the application of SLM technique for the production of soft magnetic alloys,focusing on Fe-Si,Fe-Ni,Fe-Co,and amorphous alloy systems.Moreover,it explores the implementation of SLM in manufacturing processes and evaluates both the opportunities and challenges associated with SLM-based production of soft magnetic alloys.
基金supported by the National KeyR&D Program of China(Grant No.2024YFB3817400)the National Natural Science Foundation of China(Grants No.12274276 and No.U24A6002)+1 种基金the Natural Science Foundation of Shanxi Province(China)(Grant No.202403021223008)Supported by Scientific and Technology Innovation Programs of Higher Education Institutions in Shanxi(Grant No.2024Q017 and No.2025L043).
文摘Layered transition-metal compounds(LTMCs)feature stacked architectures,strong magnetic anisotropy,and tunable magnetic order,making them promising material platforms for low-power spintronic technologies and for enabling topological functionalities in the post-Moore era.Here we review recent progress on two-dimensional(2D)magnetism in LTMCs,emphasizing material taxonomy,intrinsic magnetic properties,and external-field controls.This review first presents a classification of LTMCs by crystal structure and chemistry—binary halides,chalcogenides,and ternary families(e.g.,MPX_(3),M_(m)X_(n)Te_(k),MnBi_(2)Te_(4))—followed by a summary of their coupling mechanisms,ordering temperatures,and dimensional effects.It then analyzes the modulation of exchange interactions,magnetic anisotropy,and topological states by electric-field gating,strain engineering,and ion intercalation,with representative experimental demonstrations.Notable advances include room-temperature ferromagnetic metals and semiconductors,observation of the quantum anomalous Hall effect(QAHE)in MnBi2Te4,and synergistic control of magnetic-topological states under multiple external stimuli.Persistent challenges involve the limited availability of intrinsic 2D magnetic semiconductors with high Curie temperatures(Tc),incomplete understanding of the microscopic couplings at interfaces and under quantum confinement,and device-level stability.We conclude by outlining opportunities that lie in the integration of multiscale characterization,first-principles theory,and cross-scale fabrication to precisely co-engineer magnetism,topology,and electronic structure,thereby advancing LTMCs toward spintronic and topological-quantum applications.
基金supported by the National Natural Science Foundation of China(Grant Nos.11904312 and 11904313)the Project of Hebei Educational Department,China(Grant Nos.ZD2018015 and QN2018012)the Natural Science Foundation of Hebei Province,China(Grant No.A2019203507).
文摘First-principles calculations and Monte Carlo simulations reveal that single-layer and double-layer VX_(2)(X=Cl,Br)can be tuned from antiferromagnetic(AFM)semiconductors to ferromagnetic(FM)state when biaxial tensile stress is applied.Their ground states are all T phase.The biaxial tensile stress at the phase transition point of the double-layer VX_(2) is larger than that of the single-layer VX_(2).The direct band gaps can be also manipulated by biaxial tensile stress as they increases with increasing tensile stress to a critical point and then decreases.The Neel temperature(´TN)of double-layer VX_(2) are higher than that of single-layer.As the stress increases,the TN of all materials tend to increase.The magnetic moment increases with the increase of biaxial tensile stress,and which become insensitive to stress after the phase transition points.Our research provides a method to control the electronic and magnetic properties of VX_(2) by stress,and the single-layer and double-layer VX_(2) may have potential applications in nano spintronic devices.
文摘In this study,a multifunctional aptamer-conjugated magnetic covalent organic framework(COF)-CuO/Au nanozyme(MCOF-CuO/Au@apt)was developed as a“three-in-one”platform for dual-signal colorimetric and fluorescent detection of Vibrio parahaemolyticus.The nanozyme integrated magnetic separation,peroxidase-like catalytic activity,and specific target recognition through an aptamer-based strategy.Upon binding to V.parahaemolyticus,the catalytic oxidation of tetra-aminophenylethylene(TPE-4A)by the nanozyme was selectively inhibited,resulting in distinct colorimetric and fluorescent signals that significantly enhanced the detection accuracy and reliability.The proposed method exhibited high sensitivity,with limits of detection(LOD)of 21 and 7 CFU/mL for the colorimetric and fluorescent assays,respectively.The performance of this method was validated using real seafood samples,including Penaeus vannamei,Mytilus coruscus,and Crassostrea gigas,which showed high recovery rates(101.11%-107.30%)and excellent reproducibility.The system also demonstrated strong specificity and accuracy under various conditions,confirming its robustness and practical applicability.Collectively,this innovative platform presents a promising solution for the rapid,versatile,and sensitive detection of V.parahaemolyticus in seafood,with considerable potential to advance food safety diagnosis and on-site monitoring.
文摘Dissimilar AZ31B magnesium alloy and DC56D steel were welded via AA1060 aluminum alloy by magnetic pulse welding.The effects of primary and secondary welding processes on the welded interface were comparatively investigated.Macroscopic morphology,microstructure,and interfacial structure of the joints were analyzed using scanning electron microscope,energy dispersive spectrometer,and X-ray diffractometer(XRD).The results show that magnetic pulse welding of dissimilar Mg/Fe metals is achieved using an Al interlayer,which acts as a bridge for deformation and diffusion.Specifically,the AZ31B/AA1060 interface exhibits a typical wavy morphology,and a transition zone exists at the joint interface,which may result in an extremely complex microstructure.The microstructure of this transition zone differs from that of AZ31B magnesium and 1060 Al alloys,and it is identified as brittle intermetallic compounds(IMCs)Al_(3)Mg_(2) and Al_(12)Mg_(17).The transition zone is mainly distributed on the Al side,with the maximum thickness of Al-side transition layer reaching approximately 13.53μm.Incomplete melting layers with varying thicknesses are observed at the primary weld interface,while micron-sized hole defects appear in the transition zone of the secondary weld interface.The AA1060/DC56D interface is mainly straight,with only a small number of discontinuous transition zones distributed intermittently along the interface.These transition zones are characterized by the presence of the brittle IMC FeAl_(3),with a maximum thickness of about 4μm.
基金supported by the National Natural Science Foundation of China(Grant Nos.12488201,12274390,12304035,and 51627901)the Anhui Initiative in Quantum Information Technologies(Grant No.AHY160000)+3 种基金the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302802)the National Key R&D Program of the MOST of China(Grant No.2022YFA1602600)the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)the National Key R&D Program of China(Grant No.2023YFA1607701)。
文摘Chiral magnets have attracted considerable attention due to their intricate magnetic properties,among which B20compounds constitute a quintessential class that has gained significant focus,particularly in the study of skyrmions.MnGe,as a member of the B20 family,exhibits a more complex magnetic structure compared with other materials with similar crystal structures.In this work,we successfully synthesized high-quality MnGe thin films and characterized their magnetoresistance,M-H curves,magneto-Seebeck effect,and magnetic force microscopy(MFM)images,all of which demonstrate pronounced magnetic anisotropy.Notably,the Seebeck coefficient exhibits a plateau at low magnetic fields when the magnetic field is applied in the film plane,indicating a field region in which the magnetic structure remains stable.MFM imaging further reveals magnetic transitions within the MnGe films when the magnetic field is oriented along the film plane.These findings are crucial for advancing our understanding of the magnetic ground state of MnGe and the evolution of its magnetic structure under an applied external magnetic field.
文摘T he residual stray magnetic fields present in ferromagnetic casting slabs were investigated in this work,which result from the magnetic fields generated during the steel casting process.Existing optical detection methods face challenges owing to surface oxide scales,and conventional high-precision magnetic sensors are ineffective at high temperatures.To overcome these limitations,a small coil sensor was employed to measure the residual magnetism strength in oscillation traces,using metal magnetic memory and electromagnetic induction methods,which can carry out detection without an external excitation source.Using this technology,the proposed scheme successfully detects defects at high tempe-ratures(up to 670℃)without a cooling device.The key findings include the ability to detect both surface and near-surface defects,such as cracks and oscillation marks,with an enhanced signal-to-noise ratio(SNR)of 7.2 dB after signal processing.The method’s practicality was validated in a steel mill environment,where testing on casting slabs effectively detected defects,providing a foundation for improving industrial quality control.The proposed detection scheme offers a significant advancement in nondestructive testing(NDT)for high-temperature applications,contributing to more efficient and accurate monitoring of ferromagnetic material integrity.
文摘Under hydrothermal and solvothermal conditions,two novel cobalt-based complexes,{[Co_(2)(CIA)(OH)(1,4-dtb)]·3.2H_(2)O}n(HU23)and{[Co_(2)(CIA)(OH)(1,4-dib)]·3.5H2O·DMF}n(HU24),were successfully constructed by coordinatively assembling the semi-rigid multidentate ligand 5-(1-carboxyethoxy)isophthalic acid(H₃CIA)with the Nheterocyclic ligands 1,4-di(4H-1,2,4-triazol-4-yl)benzene(1,4-dtb)and 1,4-di(1H-imidazol-1-yl)benzene(1,4-dib),respectively,around Co^(2+)ions.Single-crystal X-ray diffraction analysis revealed that in both complexes HU23 and HU24,the CIA^(3-)anions adopt aκ^(7)-coordination mode,bridging six Co^(2+)ions via their five carboxylate oxygen atoms and one ether oxygen atom.This linkage forms tetranuclear[Co4(μ3-OH)2]^(6+)units.These Co-oxo cluster units were interconnected by CIA^(3-)anions to assemble into 2D kgd-type structures featuring a 3,6-connected topology.The 2D layers were further connected by 1,4-dtb and 1,4-dib,resulting in 3D pillar-layered frameworks for HU23 and HU24.Notably,despite the similar configurations of 1,4-dtb and 1,4-dib,differences in their coordination spatial orientations lead to topological divergence in the 3D frameworks of HU23 and HU24.Topological analysis indicates that the frameworks of HU23 and HU24 can be simplified into a 3,10-connected net(point symbol:(4^(10).6^(3).8^(2))(4^(3))_(2))and a 3,8-connected tfz-d net(point symbol:(4^(3))_(2)((4^(6).6^(18).8^(4)))),respectively.This structural differentiation confirms the precise regulatory role of ligands on the topology of metal-organic frameworks.Moreover,the ultraviolet-visible absorption spectra confirmed that HU23 and HU24 have strong absorption capabilities for ultraviolet and visible light.According to the Kubelka-Munk method,their bandwidths were 2.15 and 2.08 eV,respectively,which are consistent with those of typical semiconductor materials.Variable-temperature magnetic susceptibility measurements(2-300 K)revealed significant antiferromagnetic coupling in both complexes,with their effective magnetic moments decreasing markedly as the temperature lowered.CCDC:2457554,HU23;2457553,HU24.
基金supported in part by the National Natural Science Foundation of China under grant 52175556the Macao Science and Technology Development Fund under grant 0004/2022/AKP,0102/2022/A2,and 0078/2023/RIB3+1 种基金the Research Committee of the University of Macao under grants MYRG2022-00068-FST and MYRG-CRG202200004-FST-ICIthe Guangdong Basic and Applied Basic Research Foundation under grant 2023A1515011178。
文摘In recent years,the rising incidence of gastrointestinal(GI)cancer has triggered an urgent need for effective early intervention strategies.Traditional endoscopic techniques often cause patient discomfort,and it is difficult to navigate deep regions of complex organ structures.This work proposes a kind of bio-inspired magnetic soft robot(BMSR)to address these challenges.The design of the BMSRs is inspired by the rolling motion of the golden wheel spider.Two six-degree-of-freedom(6-DOF)robotic arms are used,where one arm is responsible for real-time manipulation of the BMSRs,and the other is dedicated to monitoring their status.Under the actuation of an external rotating magnetic field,the BMSRs can flexibly climb on inclined surfaces at any angle,involving the inverted surface.Through the powerful output force,the BMSRs can overcome the mobility barrier induced by different human organs,including mucus,folds,and height differences of up to 8 cm.Such an exceptional mobility enables the BMSRs to deliver drugs in the targeted complex GI environment.Moreover,in combination with an endoscope,it provides real-time visual feedback for precise navigation.In vitro animal experiments validate the feasibility of BMSRs,paving a way for their usage in minimally invasive GI treatment.This work advances the potential applications of magnetic soft robots in the biomedical field.
基金supported by the Singapore Ministry of Education through MOE Tier 2 grant(MOE-T2EP10223-0006)the Australia Research Council(DP190100150,DE250100232)+2 种基金Singapore-International Synchrotron Access Programme(SG-SAP)the funding support from the RIE 2025 Industry Alignment FundIndustry Collaboration Projects(IAF-ICP)(Award I2301E0023),administered by A*STARsupported by Nanofilm Technologies International Limited。
文摘The spin-sensitive nature of redox reactions in energy conversion systems,such as the oxygen evolution reaction(OER),has attracted increasing attention due to its potential for enhancing catalytic efficiency.Magnetic fields(MFs)have been proposed to enhance OER performance by influencing the spin states of oxygen intermediates.However,prior study has predominantly focused on MF effects mediated by the intrinsic magnetic properties of electrocatalysts or magnetohydrodynamics.In this work,we report a universal enhancement in OER activity,achieving over 150% increase in current density under a200 mT MF across diamagnetic,paramagnetic and magnetic electrocatalysts in 1 M KOH.Through systematic investigation of MF orientation and strength,pH,applied potentials,and the use of benzoquinone radical scavenger,we demonstrate that MF-driven performance improvements arise from direct modulation of oxygen radical spin states.Specifically,MFs promote the formation of spin-triplet oxygen intermediates(↑O–O↑),a critical step for O–O bond formation,independent of the catalyst's intrinsic magnetism.However,the local magnetic environment near the catalyst surface,governed by its magnetic properties,indirectly influences radical spin dynamics by alternating the effective field experienced by intermediates.These findings redefine the role of spin manipulation in electrocatalysis,advancing understanding of MF-driven spin effects in redox reactions.
文摘The Circular Electron Positron Collider(CEPC)proposed in China is a dual-ring collider with electron and positron beams in the energy range of 45.5–180 GeV.The main dipole in the CEPC collider is a dual-aperture dipole with a shared coil between the two apertures,forming an I-shaped structure that can reduce power consumption by 50%.Because of its long length and low field strength,the development of this dual-aperture magnet faces challenges regarding its mechanical design,field measurement accuracy,and field performance.Numerical simulations were performed to better understand the Earth's field and the effect of different BH curves on field performance.The field results of the prototype are presented herein,and the field quality satisfies the requirements.The remanent field accounts for 2%of the integral field at 140 Gs,and the hysteresis effect caused an increase in field strength of approximately 0.075%after a standardization cycle of the trim coils.Research on this prototype can provide useful insights for understanding low-field dipole magnets.
基金supported by the CAS Pioneer Hundred Talents Program and Second Tibetan Plateau Scientific Expedition Research Program(2019QZKK0708)as well as the Basic Research Program of Qinghai Province:Lithospheric Geomagnetic Field of the Qinghai-Tibet Plateau and the Relationship with Strong Earthquakes(2021-ZJ-969Q).
文摘The National Geophysical Data Center(NGDC)of the United States has collected aeromagnetic data for input into a series of geomagnetic models to improve model resolution;however,in the Tibetan Plateau region,ground-based observations remain insufficient to clearly reflect the characteristics of the region’s lithospheric magnetism.In this study,we evaluate the lithospheric magnetism of the Tibetan Plateau by using a 3D surface spline model based on observations from>200 newly constructed repeat stations(portable stations)to determine the spatial distribution of plateau geomagnetism,as well as its correlation with the tectonic features of the region.We analyze the relationships between M≥5 earthquakes and lithospheric magnetic field variations on the Tibetan Plateau and identify regions susceptible to strong earthquakes.We compare the geomagnetic results with those from an enhanced magnetic model(EMM2015)developed by the NGDC and provide insights into improving lithospheric magnetic field calculations in the Tibetan Plateau region.Further research reveals that these magnetic anomalies exhibit distinct differences from the magnetic-seismic correlation mechanisms observed in other tectonic settings;here,they are governed primarily by the combined effects of compressional magnetism,thermal magnetism,and deep thermal stress.This study provides new evidence of geomagnetic anomalies on the Tibetan Plateau,interprets them physically,and demonstrates their potential for identifying seismic hazard zones on the Plateau.
基金supported by the Beijing Natural Science Foundation(Grant No.Z230006)the National Key Research and Development Program of China(Grant No.2022YFA1204000)the National Natural Science Foundation of China(Grant Nos.12274405 and 12393831)。
文摘We report the development of the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice with strong spin-orbit torque,large perpendicular magnetic anisotropy,and remarkably low switching current density.We demonstrate that the efficiency of the spin-orbit torque increases nearly linearly with the repetition number n,which is in excellent agreement with the spin Hall effect of the Pt_(0.75)Ti_(0.25)being essentially the only source of the observed spin-orbit torque.The perpendicular magnetic anisotropy field is also substantially enhanced by more than a factor of 2 as n increases from 1 to6.The[Pt_(0.75)Ti_(0.25)/Co-Ni multilayers/Ta]_n superlattice additionally exhibits deterministic,low-current-density magnetization switching despite the very large total layer thicknesses.The unique combination of strong spin-orbit torque,robust perpendicular magnetic anisotropy,low-current-density switching,and excellent high thermal stability makes the[Pt_(0.75)Ti_(0.25)/Co-Ni multilayer/Ta]_n superlattice a highly compelling material candidate for ultrafast,energy-efficient,and long-data-retention spintronic technologies.
基金Project supported by the National Key Research and Decelopment Program of China(Grant No.2021YFB3500302)the National Natural Science Foundation of China(Grant Nos.U22A20116 and 52371200)the Innovation Capability Improvement Project of Hebei Province,China(Grant No.22567605H)。
文摘Large magnetic entropy change(△S_(M))can realize a prominent heat transformation under the magnetic field and directly strengthen the efficacy of the magnetocaloric effect,which provides a pioneering environmentally friendly solidstate strategy to improve refrigeration capacities and efficiencies.The second-order magnetic transition(SOMT)materials have broader△S_(M) peaks without thermal hysteresis,making them highly attractive in magnetic refrigeration,especially in the room temperature range.Here,we report a significant enhancement of△S_(M) at room temperature in single-crystal Mn_(5)Ge_(3).In this SOMT system,we realize a 60%improvement of-△S_(M)^(max) from 3.5 J/kg·K to 5.6 J/kg·K at T=300 K.This considerable enhancement of△S_(M) is achieved by intentionally introducing strain energy through high-pressure constrained deformation.Both experimental results and Monte Carlo simulations demonstrate that the enhancement of△S_(M) originates from the microscopic strain and lattice deformation induced by strain energy after deformation.This strain energy will reconstruct the energy landscape of this ferromagnetic system and enhance magnetization,resulting in a giant intensity of magnetocaloric responses.Our findings provide an approach to increase magnetic entropy change and may give fresh ideas for exploring advanced magnetocaloric materials.
