This study focused on investigating the effects of various factors on the mechanical properties of superconducting matrix composites reinforced with ferromagnetic particles and interface phases when exposed to externa...This study focused on investigating the effects of various factors on the mechanical properties of superconducting matrix composites reinforced with ferromagnetic particles and interface phases when exposed to external magnetic fields.A micromechanical model was created by simplifying the basic properties and composition of the interface,utilizing principles such as Eshelby’s equivalent inclusion theory and Hooke’s law,as well as applying uniform stress boundary conditions.Through the development of equations,the study predicted changes in effective mechanical properties,highlighting the significant influence of parameters like the interface phase,inclusions,and magnetic field on the effective elastic modulus and magnetostriction of the composite material.By shedding light on these relationships,the research offers valuable insights for the manufacture and application of ferromagnetic particle-reinforced superconducting matrix composites with interface phases,providing a foundation for future research in this area.展开更多
We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the p...We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.展开更多
In this paper,the Lie symmetry analysis method is applied to the(2+1)-dimensional time-fractional Heisenberg ferromagnetic spin chain equation.We obtain all the Lie symmetries admitted by the governing equation and re...In this paper,the Lie symmetry analysis method is applied to the(2+1)-dimensional time-fractional Heisenberg ferromagnetic spin chain equation.We obtain all the Lie symmetries admitted by the governing equation and reduce the corresponding(2+1)-dimensional fractional partial differential equations with the Riemann–Liouville fractional derivative to(1+1)-dimensional counterparts with the Erdélyi–Kober fractional derivative.Then,we obtain the power series solutions of the reduced equations,prove their convergence and analyze their dynamic behavior graphically.In addition,the conservation laws for all the obtained Lie symmetries are constructed using the new conservation theorem and the generalization of Noether operators.展开更多
Motivated by recent studies of the cluster Mott insulator candidate compound Nb_(3)Cl_(8),this study performs^(93)Nb and^(35)Cl nuclear magnetic resonance(NMR)measurements to investigate the electron correlations.Belo...Motivated by recent studies of the cluster Mott insulator candidate compound Nb_(3)Cl_(8),this study performs^(93)Nb and^(35)Cl nuclear magnetic resonance(NMR)measurements to investigate the electron correlations.Below the structural transition temperature T_(s)∼97 K,all satellites of the^(93)Nb NMR spectra split into three distinct peaks,which suggests symmetry lowering due to the structural transition and could be attributed to the change in the Nb-Nb bond-lengths of the Nb3 clusters.The spin-lattice relaxation rate 1/T_(1)divided by the temperature T,1/T_(1)T,increases upon cooling to T_(s)for all Cl sites,whereas only the Knight shift K of Cl located at the center of the Nb_(3) clusters exhibits a temperature dependence similar to that observed in magnetic susceptibility.These findings collectively demonstrate the existence of strong spin correlations between the Nb atoms in Nb_(3)Cl_(8),which are closely associated with Mottness.展开更多
The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonl...The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.展开更多
Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_...Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.展开更多
The interfacial characteristics of the Li metal anode(LMA)play a crucial role in its overall performance.Despite various materials being applied to modify the interface,a comprehensive understanding of their specific ...The interfacial characteristics of the Li metal anode(LMA)play a crucial role in its overall performance.Despite various materials being applied to modify the interface,a comprehensive understanding of their specific mechanisms remains to be investigated.Herein,we have prepared carbon cloth(CC)frameworks with their surfaces modified using ferromagnetic metal/LiF heterogeneous films(T^(M)-LiF-CC)as the substrate for LMA,which exhibit superior electrochemical performance.Utilizing ferromagnetic Co as a representative example,our study demonstrates that the enhanced performance of Co-LiF-CC,compared to bare CC,is attributed to the spinpolarized interface contributed by the Co/LiF heterostructure.Co and LiF play individual roles in redistributing electrons and Li^(+)to promote homogeneous Li deposition.Co nanoparticles play a crucial role in generating strong surface capacitance by storing electrons in spin-split bands,while LiF,with low surface diffusion barriers,ensures fast transportation of Li^(+).The Co-LiF-CC@Li electrodes deliver long lives of 7400 and 3600 h at 1 and 2 mA·cm^(-2)in symmetric cells,respectively;moreover,they enable full batteries with high and durable capacities,particularly when the N/P ratios are low(3.3 or even 1.7).展开更多
Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers...Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers that can be used to print soft robots with complex structures.These ferromagnetic fibers are recyclable and can make soft robots sustainable.The ferromagnetic fibers based on thermoplastic polyurethane(TPU)/NdFeB hybrid particles are extruded by an extruder.We use a desktop three-dimensional(3D)printer to demonstrate the feasibility of printing two-dimensional(2D)and complex 3D soft robots.These printed soft robots can be recycled and reprinted into new robots once their tasks are completed.Moreover,these robots show almost no difference in actuation capability compared to prior versions and have new functions.Successful applications include lifting,grasping,and moving objects,and these functions can be operated untethered wirelessly.In addition,the locomotion of the magnetic soft robot in a human stomach model shows the prospect of medical applications.Overall,these fully recyclable ferromagnetic fibers pave the way for printing and reprinting sustainable soft robots while also effectively reducing e-waste and robotics waste materials,which is important for resource conservation and environmental protection.展开更多
Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we r...Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we report the enhancement in the room-temperature plasticity during the compression(25%)and bending flexibility of Fe_(74)Mo_(6)P_(13)C_(7) FBMG by using water quenching.The high-energy synchrotron X-ray measurements,high-resolution transmission electron microscopy,three-dimensional X-ray microtomog-raphy,and finite element simulation were performed to reveal the origin.It was found that the M-shape profile of residual stress improves the mechanical properties of FBMGs,particularly their plasticity.The reversal of the heat-transfer coefficient and cooling rate from the'vapor blanket'to'nucleate boiling'transition during water quenching processing is the main cause of the unusual profile of residual stress in glassy cylinders.Encouraged by the progress in developing flexible silicate glasses,this work highlights a processing method to improve plasticity and surmount technical barriers for the commercialization of FBMGs.展开更多
Antiferromagnet(AFM)/ferromagnet(FM)heterostructure is a popular system for studying the spin–orbit torque(SOT)of AFMs.However,the interfacial exchange bias field induces that the magnetization in FM layer is noncoll...Antiferromagnet(AFM)/ferromagnet(FM)heterostructure is a popular system for studying the spin–orbit torque(SOT)of AFMs.However,the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field,namely the magnetic moment drag effect,which further influences the characteristic of SOT efficiency.In this work,we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance(ST-FMR)method.A full analysis on the AFM/FM systems with exchange bias is performed,and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free energy.The ST-FMR results can be well fitted by this model.We obtained the relative accurate SOT efficiencyξ_(DL)=0.058 for the IrMn film.This work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.展开更多
Concise chemistry leads to a family of heptanuclear Co^(Ⅱ)-clusters,[Co_(7)(N_(3))_(12)(CH_(3)CN)_(12)][Y_(2)(NO_(3))_(4)(piv)_(4)]·2CH_(3)CN(DC1)(pivH=pivalic acid),[Co_(7)(N_(3))_(12)(CH_(3)CN)_(10)(NO_(3))_(0...Concise chemistry leads to a family of heptanuclear Co^(Ⅱ)-clusters,[Co_(7)(N_(3))_(12)(CH_(3)CN)_(12)][Y_(2)(NO_(3))_(4)(piv)_(4)]·2CH_(3)CN(DC1)(pivH=pivalic acid),[Co_(7)(N_(3))_(12)(CH_(3)CN)_(10)(NO_(3))_(0.4)(Cl)_(1.6)]·4CH_(3)CN(DC2)and[Co_(7)(N_(3))_(12)(CH_(3)CN)_(10)(NO_(3))_(2)]·4CH_(3)CN(DC3),in which the metal ions are exclusively bridged by end-on azido ligands to stabilize a beautiful disk-like topology.The resulting clusters exhibit interesting structural transformations and thermodynamically-distinct steady states verified by theoretical calcula-tions.Magnetic studies reveal the first observation of zero-field SMM behaviour in disk-like heptanuclear Co^(Ⅱ)complexes.展开更多
Understanding the photoexcitation induced spin dynamics in ferromagnetic metals is important for the design of photo-controlled ultrafast spintronic device.In this work,by the ab initio nonadiabatic molecular dynamics...Understanding the photoexcitation induced spin dynamics in ferromagnetic metals is important for the design of photo-controlled ultrafast spintronic device.In this work,by the ab initio nonadiabatic molecular dynamics simulation,we have studied the spin dynamics induced by spin–orbit coupling(SOC)in Co and Fe using both spin-diabatic and spin-adiabatic representations.In Co system,it is found that the Fermi surface(E_(F))is predominantly contributed by the spin-minority states.The SOC induced spin flip will occur for the photo-excited spin-majority electrons as they relax to the E_(F),and the spin-minority electrons tend to relax to the EFwith the same spin through the electron–phonon coupling(EPC).The reduction of spin-majority electrons and the increase of spin-minority electrons lead to demagnetization of Co within100 fs.By contrast,in Fe system,the E_(F) is dominated by the spin-majority states.In this case,the SOC induced spin flip occurs for the photo-excited spin-minority electrons,which leads to a magnetization enhancement.If we move the E_(F) of Fe to higher energy by 0.6eV,the E_(F) will be contributed by the spin-minority states and the demagnetization will be observed again.This work provides a new perspective for understanding the SOC induced spin dynamics mechanism in magnetic metal systems.展开更多
Determination of the magnetic structure and confirmation of the presence or absence of inversion(P)and time reversal(Τ)symmetry is imperative for correctly understanding the topological magnetic materials.Here highqu...Determination of the magnetic structure and confirmation of the presence or absence of inversion(P)and time reversal(Τ)symmetry is imperative for correctly understanding the topological magnetic materials.Here highquality single crystals of the layered manganese pnictide CaMnSb_(2)are synthesized using the self-flux method.展开更多
A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Mont...A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations,we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications.展开更多
Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done wi...Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental data.In addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic phase.For ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)states.Additionally,Curie temperatures of ferromagnetic phases were also estimated.We used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of Ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and DOS.Further,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied spinels.In addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.展开更多
Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical...Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method.We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single-and two-magnon excitations,respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.展开更多
Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co...Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co_(2)Sn considered as a ferromagnetic(FM)Weyl semimetal.The cusp anomaly of temperature-dependent resistivity and large isotropic negative magneto-resistivity(MR)emerge around the FM transition consistent with the theoretical half-metallic predictions.The prominent anomalous Hall effect(AHE)has the same behavior with the applied field along various crystal directions.The Nb doping introduces more disorder resulting in the enhancement of the upturn for the temperature-dependent resistivity in low temperatures.With Nb doping,the AHE exhibits systemic evolution with the Fermi level lifted.At the doping level of x=0.25,the AHE mainly originates from the intrinsic contribution related to non-trivial topological Weyl states.展开更多
The realization of 100%polarized topologicalWeyl fermions in half-metallic ferromagnets is of particular importance for fundamental research and spintronic applications.Here,we theoretically investigate the electronic...The realization of 100%polarized topologicalWeyl fermions in half-metallic ferromagnets is of particular importance for fundamental research and spintronic applications.Here,we theoretically investigate the electronic and topological properties of the zinc-blende compound VAs,which was deemed as a half-metallic ferromagnet related to dynamic correlations.Based on the combination of density functional theory and dynamical mean field theory,we uncover that the half-metallic ferromagnet VAs exhibits attractive Weyl semimetallic behaviors which are very close to the Fermi level in the DFT+U regime with effect U values ranging from 1.5 eV to 2.5 eV.Meanwhile,we also investigate the magnetization-dependent topological properties;the results show that the change of magnetization directions only slightly affects the positions of Weyl points,which is attributed to the weak spin–orbital coupling effects.The topological surface states of VAs projected on semi-infinite(001)and(111)surfaces are investigated.The Fermi arcs of all Weyl points are clearly visible on the projected Fermi surfaces.Our findings suggest that VAs is a fully spin-polarized Weyl semimetal with many-body correlated effects in the effective U values range from 1.5 eV to 2.5 eV.展开更多
Based on the proper assumptions and approximations, the coupling mechanism of the electromagnetic acoustic transducer (EMAT) for ultrasonic generation within ferromagnetic material was studied by analyzing the eddy cu...Based on the proper assumptions and approximations, the coupling mechanism of the electromagnetic acoustic transducer (EMAT) for ultrasonic generation within ferromagnetic material was studied by analyzing the eddy current distribution, Lorentz force, magnetostriction force and magnetization force. Some useful numerical calculations are presented to explain the EMAT behavior with general geometric arrangements. It is indicated that for the ferromagnetic material the magnetostriction effect dominates the EMAT phenomenon for ultrasonic wave generation in low magnetic field intensity, while the material does not reach its magnetizing saturation. But, with the increase of the bias magnetic field and saturation, the magnetostrictive terms will make no contributions to the ultrasonic generation and the Lorentz force becomes the only exciting mechanism. It is important to determine both the Lorentz and magnetostriction forces and select the appropriate working manner for achieving an optimized design.展开更多
The Co2FeSi films are deposited on Si （100） substrates by an oblique sputtering method at ambient temperature. It is revealed that the microwave ferromagnetic properties of Co2FeSi films are sensitive to sample posi...The Co2FeSi films are deposited on Si （100） substrates by an oblique sputtering method at ambient temperature. It is revealed that the microwave ferromagnetic properties of Co2FeSi films are sensitive to sample position and sputtering power. It is exciting that the as-deposited films without any magnetic annealing exhibit high in-plane uniaxial anisotropy fields in a range of 200 Oe-330 Oe （1 Oe = 79.5775 A.m ^-1）, and low coercivities in a range of 5 Oe-28 Oe. As a result, high self-biased ferromagnetic resonance frequency up to 4.75 GHz is achieved in as-deposited oblique sputtered films. These results indicate that Co2FeSi Heusler alloy films are promising in practical applications of RF/microwave devices.展开更多
基金supported by the National Natural Science Foundation of China(No.12262020).
文摘This study focused on investigating the effects of various factors on the mechanical properties of superconducting matrix composites reinforced with ferromagnetic particles and interface phases when exposed to external magnetic fields.A micromechanical model was created by simplifying the basic properties and composition of the interface,utilizing principles such as Eshelby’s equivalent inclusion theory and Hooke’s law,as well as applying uniform stress boundary conditions.Through the development of equations,the study predicted changes in effective mechanical properties,highlighting the significant influence of parameters like the interface phase,inclusions,and magnetic field on the effective elastic modulus and magnetostriction of the composite material.By shedding light on these relationships,the research offers valuable insights for the manufacture and application of ferromagnetic particle-reinforced superconducting matrix composites with interface phases,providing a foundation for future research in this area.
基金supported by the National Key R&D Program of China (Grant No. 2024YFA1408502)the National Natural Science Foundation of China (Grant Nos. 92365102, 62027807, 12474107, and 12174383)+1 种基金the Chinese Academy of Sciences project for Yong Scientists in Basic Research (Grant No. YSBR-030)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515011600)。
文摘We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.
基金supported by the State Key Program of the National Natural Science Foundation of China(72031009).
文摘In this paper,the Lie symmetry analysis method is applied to the(2+1)-dimensional time-fractional Heisenberg ferromagnetic spin chain equation.We obtain all the Lie symmetries admitted by the governing equation and reduce the corresponding(2+1)-dimensional fractional partial differential equations with the Riemann–Liouville fractional derivative to(1+1)-dimensional counterparts with the Erdélyi–Kober fractional derivative.Then,we obtain the power series solutions of the reduced equations,prove their convergence and analyze their dynamic behavior graphically.In addition,the conservation laws for all the obtained Lie symmetries are constructed using the new conservation theorem and the generalization of Noether operators.
基金supported by the National Key Research and Development Projects of China(Grant Nos.2022YFA1403402,2023YFA1406103,2024YFA1409200,2024YFA1611302,and 2023YFF0718400)the National Natural Science Foundation of China(Grant Nos.12374142,12304170,W2411004,and 12374197)+3 种基金the Beijing Natural Science Foundation(Grant No.JQ23001)the Beijing National Laboratory for Condensed Matter Physics(Grant No.2024BNLCMPKF005)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2023B151520013)supported by the Synergetic Extreme Condition User Facility(SECUF,https://cstr.cn/31123.02.SECUF)。
文摘Motivated by recent studies of the cluster Mott insulator candidate compound Nb_(3)Cl_(8),this study performs^(93)Nb and^(35)Cl nuclear magnetic resonance(NMR)measurements to investigate the electron correlations.Below the structural transition temperature T_(s)∼97 K,all satellites of the^(93)Nb NMR spectra split into three distinct peaks,which suggests symmetry lowering due to the structural transition and could be attributed to the change in the Nb-Nb bond-lengths of the Nb3 clusters.The spin-lattice relaxation rate 1/T_(1)divided by the temperature T,1/T_(1)T,increases upon cooling to T_(s)for all Cl sites,whereas only the Knight shift K of Cl located at the center of the Nb_(3) clusters exhibits a temperature dependence similar to that observed in magnetic susceptibility.These findings collectively demonstrate the existence of strong spin correlations between the Nb atoms in Nb_(3)Cl_(8),which are closely associated with Mottness.
基金supported by the National Natural Science Foundation of China(No.12172321)。
文摘The nonlinear traveling wave vibration of rotating ferromagnetic functionally graded(FG)cylindrical shells under multi-physics fields is investigated.Grounded in the Kirchhoff-Love thin shell theory,the geometric nonlinearity is incorporated into the model,and the constitutive equations are derived.The physical parameters of functionally graded materials(FGMs),which exhibit continuous variation across the thickness gradient,are of particular interest.The nonlinear magneto-thermoelastic governing equations are derived in accord with Hamilton's principle.The nonlinear partial differential equations are discretized with the Galerkin method,and the analytical expression of traveling wave frequencies is derived with an approximate method.The accuracy of the proposed method is validated through the comparison with the results from the literature and numerical solutions.Finally,the visualization analyses are conducted to examine the effects of key parameters on the traveling wave frequencies.The results show that the factors including the power-law index,temperature,magnetic field intensity,and rotating speed have the coupling effects with respect to the nonlinear vibration behavior.
基金the Deanship of Scientific Research at King Khalid University for funding this work through large group Research Project under grant number RGP2/450/44。
文摘Spintronic technology and energy applications benefit greatly from the exceptional characteristics of rare-earth-based spinel chalcogenides.Examining the electrical,magnetic and thermoelectric properties of HgNd_(2)Z_(4)(Z=S,Se)in a systematic manner is essential for the strategic advancement of spin polarized current in a spintronic device.In this recent study,the WIEN2K code was employed to comprehensively analyze these properties.The calculated lattice constants,obtained using the generalized gradient approximation(GGAsol-PBE),closely match experimental findings of the similar family compounds.The examination of the stability of ferromagnetic states in the ground state involves comparing energies between anti-ferromagnetic and ferromagnetic states.Moreover,an assessment of the stability of the cubic phase in both spinels was conducted using analyses of the phonon dispersion curve,formation energy and Born stability criteria.The ductility characteristics were examined through the calculation of Poisson's and Pugh's ratios.Furthermore,details regarding the density of states,spin polarization,ex-change coupling and Curie temperature were provided to explore the characteristics associated with ferromagnetism.Potential optoelectronic applications were proposed,leveraging the direct band gaps of 1.4 and 1.0 eV for HgNd_(2)Z_(4)(Z=S,Se)respectively,within the visible spectrum.Particularly noteworthy is the effective light absorption of HgNd2Se4 in the visible range,characterized by prominent peaks that facilitate the transition of electrons from the valence band(VB)to the conduction band(CB).Additionally,the study extends to thermoelectric characteristics,determining various factors such as Seebeck coef-ficient(S),figure of merit(ZT),electrical and thermal conductivities of the evaluated spinels.
基金financially supported by the National Natural Science Foundation of China(No.52002270)the China Postdoctoral Science Foundation(No.2020M670661)。
文摘The interfacial characteristics of the Li metal anode(LMA)play a crucial role in its overall performance.Despite various materials being applied to modify the interface,a comprehensive understanding of their specific mechanisms remains to be investigated.Herein,we have prepared carbon cloth(CC)frameworks with their surfaces modified using ferromagnetic metal/LiF heterogeneous films(T^(M)-LiF-CC)as the substrate for LMA,which exhibit superior electrochemical performance.Utilizing ferromagnetic Co as a representative example,our study demonstrates that the enhanced performance of Co-LiF-CC,compared to bare CC,is attributed to the spinpolarized interface contributed by the Co/LiF heterostructure.Co and LiF play individual roles in redistributing electrons and Li^(+)to promote homogeneous Li deposition.Co nanoparticles play a crucial role in generating strong surface capacitance by storing electrons in spin-split bands,while LiF,with low surface diffusion barriers,ensures fast transportation of Li^(+).The Co-LiF-CC@Li electrodes deliver long lives of 7400 and 3600 h at 1 and 2 mA·cm^(-2)in symmetric cells,respectively;moreover,they enable full batteries with high and durable capacities,particularly when the N/P ratios are low(3.3 or even 1.7).
基金funded by the International Cooperation Program of the Natural Science Foundation of China(No.52261135542)Zhejiang Provincial Natural Science Foundation of China(No.LD22E050002)the Russian Science Foundation(No.23-43-00057)for financial support。
文摘Integrated printing of magnetic soft robots with complex structures using recyclable materials to achieve sustainability of the soft robots remains a persistent challenge.Here,we propose a kind of ferromagnetic fibers that can be used to print soft robots with complex structures.These ferromagnetic fibers are recyclable and can make soft robots sustainable.The ferromagnetic fibers based on thermoplastic polyurethane(TPU)/NdFeB hybrid particles are extruded by an extruder.We use a desktop three-dimensional(3D)printer to demonstrate the feasibility of printing two-dimensional(2D)and complex 3D soft robots.These printed soft robots can be recycled and reprinted into new robots once their tasks are completed.Moreover,these robots show almost no difference in actuation capability compared to prior versions and have new functions.Successful applications include lifting,grasping,and moving objects,and these functions can be operated untethered wirelessly.In addition,the locomotion of the magnetic soft robot in a human stomach model shows the prospect of medical applications.Overall,these fully recyclable ferromagnetic fibers pave the way for printing and reprinting sustainable soft robots while also effectively reducing e-waste and robotics waste materials,which is important for resource conservation and environmental protection.
基金National Natural Science Foundation of China(No.52171165)。
文摘Ferromagnetic bulk metallic glasses(FBMGs)possess excellent soft magnetic properties,good corrosion resistance,and high strength.Unfortunately,their commercial utility is limited by their brittleness.In this work,we report the enhancement in the room-temperature plasticity during the compression(25%)and bending flexibility of Fe_(74)Mo_(6)P_(13)C_(7) FBMG by using water quenching.The high-energy synchrotron X-ray measurements,high-resolution transmission electron microscopy,three-dimensional X-ray microtomog-raphy,and finite element simulation were performed to reveal the origin.It was found that the M-shape profile of residual stress improves the mechanical properties of FBMGs,particularly their plasticity.The reversal of the heat-transfer coefficient and cooling rate from the'vapor blanket'to'nucleate boiling'transition during water quenching processing is the main cause of the unusual profile of residual stress in glassy cylinders.Encouraged by the progress in developing flexible silicate glasses,this work highlights a processing method to improve plasticity and surmount technical barriers for the commercialization of FBMGs.
基金Project supported by the National Key Research and Development Program of China(Grant No.2021YFB3601300)the National Natural Science Foundation of China(Grant Nos.52201290,12074158,and 12174166)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2022-kb01)。
文摘Antiferromagnet(AFM)/ferromagnet(FM)heterostructure is a popular system for studying the spin–orbit torque(SOT)of AFMs.However,the interfacial exchange bias field induces that the magnetization in FM layer is noncollinear to the external magnetic field,namely the magnetic moment drag effect,which further influences the characteristic of SOT efficiency.In this work,we study the SOT efficiencies of IrMn/NiFe bilayers with strong interfacial exchange bias by using spin-torque ferromagnetic resonance(ST-FMR)method.A full analysis on the AFM/FM systems with exchange bias is performed,and the angular dependence of magnetization on external magnetic field is determined through the minimum rule of free energy.The ST-FMR results can be well fitted by this model.We obtained the relative accurate SOT efficiencyξ_(DL)=0.058 for the IrMn film.This work provides a useful method to analyze the angular dependence of ST-FMR results and facilitates the accurate measurement of SOT efficiency for the AFM/FM heterostructures with strong exchange bias.
基金supported by the National Natural Science Foundation of China(NSFC,Nos.21863009,22063008)the Natural Science Foundation of Ningxia Province(Nos.2023AAC03014,2023AAC03227,2021AAC03136,2021BEB04062)+1 种基金the Young Top-notch Talent Cultivation Program of Ningxia Province,the Discipline Project of Ningxia(No.NXYLXK2017A04)the China Postdoctoral Science Foundation(No.2022M723148).
文摘Concise chemistry leads to a family of heptanuclear Co^(Ⅱ)-clusters,[Co_(7)(N_(3))_(12)(CH_(3)CN)_(12)][Y_(2)(NO_(3))_(4)(piv)_(4)]·2CH_(3)CN(DC1)(pivH=pivalic acid),[Co_(7)(N_(3))_(12)(CH_(3)CN)_(10)(NO_(3))_(0.4)(Cl)_(1.6)]·4CH_(3)CN(DC2)and[Co_(7)(N_(3))_(12)(CH_(3)CN)_(10)(NO_(3))_(2)]·4CH_(3)CN(DC3),in which the metal ions are exclusively bridged by end-on azido ligands to stabilize a beautiful disk-like topology.The resulting clusters exhibit interesting structural transformations and thermodynamically-distinct steady states verified by theoretical calcula-tions.Magnetic studies reveal the first observation of zero-field SMM behaviour in disk-like heptanuclear Co^(Ⅱ)complexes.
基金support of Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0450101)the National Natural Science Foundation of China(Grant Nos.12125408 and 11974322)+1 种基金the Informatization Plan of Chinese Academy of Sciences(Grant No.CAS-WX2021SF-0105)the support of the National Natural Science Foundation of China(Grant No.12174363)。
文摘Understanding the photoexcitation induced spin dynamics in ferromagnetic metals is important for the design of photo-controlled ultrafast spintronic device.In this work,by the ab initio nonadiabatic molecular dynamics simulation,we have studied the spin dynamics induced by spin–orbit coupling(SOC)in Co and Fe using both spin-diabatic and spin-adiabatic representations.In Co system,it is found that the Fermi surface(E_(F))is predominantly contributed by the spin-minority states.The SOC induced spin flip will occur for the photo-excited spin-majority electrons as they relax to the E_(F),and the spin-minority electrons tend to relax to the EFwith the same spin through the electron–phonon coupling(EPC).The reduction of spin-majority electrons and the increase of spin-minority electrons lead to demagnetization of Co within100 fs.By contrast,in Fe system,the E_(F) is dominated by the spin-majority states.In this case,the SOC induced spin flip occurs for the photo-excited spin-minority electrons,which leads to a magnetization enhancement.If we move the E_(F) of Fe to higher energy by 0.6eV,the E_(F) will be contributed by the spin-minority states and the demagnetization will be observed again.This work provides a new perspective for understanding the SOC induced spin dynamics mechanism in magnetic metal systems.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.12074023,12304053,and 12174018)the Large Scientific Facility Open Subject of Songshan Lake(Dongguan,Guangdong)the Fundamental Research Funds for the Central Universities in China。
文摘Determination of the magnetic structure and confirmation of the presence or absence of inversion(P)and time reversal(Τ)symmetry is imperative for correctly understanding the topological magnetic materials.Here highquality single crystals of the layered manganese pnictide CaMnSb_(2)are synthesized using the self-flux method.
基金Project supported by the National Key Research and Development Program of China (Grant No.2019YFA0210004)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB30000000)+1 种基金the Fundamental Research Funds for the Central Universities (Grant No.WK3510000013)the National Supercomputing Center in Tianjin。
文摘A clear microscopic understanding of exchange bias is crucial for its application in magnetic recording, and further progress in this area is desired. Based on the results of our first-principles calculations and Monte Carlo simulations,we present a theoretical proposal for a stacking-dependent exchange bias in two-dimensional compensated van der Waals ferromagnetic/antiferromagnetic bilayer heterostructures. The exchange bias effect emerges in stacking registries that accommodate inhomogeneous interlayer magnetic interactions between the ferromagnetic layer and different spin sublattices of the antiferromagnetic layer. Moreover, the on/off switching and polarity reversal of the exchange bias can be achieved by interlayer sliding, and the strength can be modulated using an external electric field. Our findings push the limits of exchange bias systems to extreme bilayer thickness in two-dimensional van der Waals heterostructures, potentially stimulating new experimental investigations and applications.
基金the Deanship of Scientific Research at King Khalid University for funding this work through the small Groups Project under grant number(R.G.P.1/153/43)。
文摘Half-metallic ferromagnetism,mechanical as well as thermoelectric properties for rare earth-based spinels MgHo_(2)Z_(4)(Z=S,Se)were investigated using density functional theory(DFT).Structural optimization was done with Perdew-Burke-Ehrenzorf(PBE)sol-generalized gradient approximation(GGA)to calculate the lattice constant of both spinels comparable to experimental data.In addition,Born stability criteria and negative formation energy show that our studied spinels are also structurally and dynamically stable in the cubic phase.For ferromagnetic(FM)state stability,we also calculated the energy differences among FM,antiferromagnetic(AFM),and non-magnetic(NM)states.Additionally,Curie temperatures of ferromagnetic phases were also estimated.We used Trans-Blaha improved BeckeJohnson(TB-mBJ)potential functional for electronics as well as magnetic characteristics,which lead to the consistent explanation of half-metallic ferromagnetism,representing the whole band-occupancy in material with exact detail of density of states(DOS).The stable FM state was examined in spinels due to the exchange splitting of Ho cation consisting of p-d hybridizations compatible with the result achieved for electronics band structure and DOS.Further,spin magnetic moment was explained in terms of anion,cation,and sharing charge on studied spinels.In addition,the calculated thermoelectric properties clearly show that operation range of these systems may be utilized by future experimental works for identifying the potential applications of these systems.
基金Project supported by the National Key R&D Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12334008, 12174441,12134020, and 12374156)。
文摘Motivated by recent experimental progress on the quasi-one-dimensional quantum magnet Ni Nb2O6, we study the spin dynamics of an S = 1 ferromagnetic Heisenberg chain with single-ion anisotropy by using a semiclassical molecular dynamics approach. This system undergoes a quantum phase transition from a ferromagnetic to a paramagnetic state under a transverse magnetic field, and the magnetic response reflecting this transition is well described by our semiclassical method.We show that at low temperature the transverse component of the dynamical structure factor depicts clearly the magnon dispersion, and the longitudinal component exhibits two continua associated with single-and two-magnon excitations,respectively. These spin excitation spectra show interesting temperature dependence as effects of magnon interactions. Our findings shed light on the experimental detection of spin excitations in a large class of quasi-one-dimensional magnets.
基金Project supported by the National Key Research and Development Program of China (Grant Nos.2023YFF0718400 and 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos.U2130101 and 92165204)+2 种基金the Natural Science Foundation of Guangdong Province,China (Grant No.2022A1515010035)the Open Project of Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices (Grant No.2022B1212010008)the Open Project of Key Laboratory of Optoelectronic Materials and Technologies (Grant No.OEMT-2023-ZTS-01)。
文摘Magnetic topological semimetal can host various topological non-trivial states leading to exotic novel transport properties.Here we report the systematic magneto-transport studies on the Heusler alloy Nb_(x)Zr_(1-x)Co_(2)Sn considered as a ferromagnetic(FM)Weyl semimetal.The cusp anomaly of temperature-dependent resistivity and large isotropic negative magneto-resistivity(MR)emerge around the FM transition consistent with the theoretical half-metallic predictions.The prominent anomalous Hall effect(AHE)has the same behavior with the applied field along various crystal directions.The Nb doping introduces more disorder resulting in the enhancement of the upturn for the temperature-dependent resistivity in low temperatures.With Nb doping,the AHE exhibits systemic evolution with the Fermi level lifted.At the doping level of x=0.25,the AHE mainly originates from the intrinsic contribution related to non-trivial topological Weyl states.
基金the National Natural Science Foun-dation of China(Grant Nos.12204074,12222402,92365101,and 12347101)the Natural Science Foundation of Chong-ging(Grant No.CSTB2023NSCQ-JQX0024).
文摘The realization of 100%polarized topologicalWeyl fermions in half-metallic ferromagnets is of particular importance for fundamental research and spintronic applications.Here,we theoretically investigate the electronic and topological properties of the zinc-blende compound VAs,which was deemed as a half-metallic ferromagnet related to dynamic correlations.Based on the combination of density functional theory and dynamical mean field theory,we uncover that the half-metallic ferromagnet VAs exhibits attractive Weyl semimetallic behaviors which are very close to the Fermi level in the DFT+U regime with effect U values ranging from 1.5 eV to 2.5 eV.Meanwhile,we also investigate the magnetization-dependent topological properties;the results show that the change of magnetization directions only slightly affects the positions of Weyl points,which is attributed to the weak spin–orbital coupling effects.The topological surface states of VAs projected on semi-infinite(001)and(111)surfaces are investigated.The Fermi arcs of all Weyl points are clearly visible on the projected Fermi surfaces.Our findings suggest that VAs is a fully spin-polarized Weyl semimetal with many-body correlated effects in the effective U values range from 1.5 eV to 2.5 eV.
文摘Based on the proper assumptions and approximations, the coupling mechanism of the electromagnetic acoustic transducer (EMAT) for ultrasonic generation within ferromagnetic material was studied by analyzing the eddy current distribution, Lorentz force, magnetostriction force and magnetization force. Some useful numerical calculations are presented to explain the EMAT behavior with general geometric arrangements. It is indicated that for the ferromagnetic material the magnetostriction effect dominates the EMAT phenomenon for ultrasonic wave generation in low magnetic field intensity, while the material does not reach its magnetizing saturation. But, with the increase of the bias magnetic field and saturation, the magnetostrictive terms will make no contributions to the ultrasonic generation and the Lorentz force becomes the only exciting mechanism. It is important to determine both the Lorentz and magnetostriction forces and select the appropriate working manner for achieving an optimized design.
基金Project supported by the National Natural Science Foundation of China(Grant No.11074040)the Key Project of Department of Science and Technology of Shangdong Province of China(Grant No.ZR2012FZ006)
文摘The Co2FeSi films are deposited on Si （100） substrates by an oblique sputtering method at ambient temperature. It is revealed that the microwave ferromagnetic properties of Co2FeSi films are sensitive to sample position and sputtering power. It is exciting that the as-deposited films without any magnetic annealing exhibit high in-plane uniaxial anisotropy fields in a range of 200 Oe-330 Oe （1 Oe = 79.5775 A.m ^-1）, and low coercivities in a range of 5 Oe-28 Oe. As a result, high self-biased ferromagnetic resonance frequency up to 4.75 GHz is achieved in as-deposited oblique sputtered films. These results indicate that Co2FeSi Heusler alloy films are promising in practical applications of RF/microwave devices.
