Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0....Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0.3 in Sr_(2-x)Pb_(x)IrO_(4). The mapping data obtained from energy-dispersive x-ray spectroscopy analyses give solid evidence that the Pb ions are uniformly distributed in the Sr_(2)IrO_(4) matrix. The incorporation of Pb leads to a moderate depression of the canted antiferromagnetic ordering state. The electrical conductivity could be greatly enhanced when the Pb doping content is higher than x=0.2.The present results give a fresh material base to explore new physics in doped Sr_(2)IrO_(4) systems.展开更多
Topological magnetism with strong robustness,nanoscale dimensions and ultralow driving current density(106 A/m^(2))is promising for applications in information sensing,storage,and processing,and thus sparking widespre...Topological magnetism with strong robustness,nanoscale dimensions and ultralow driving current density(106 A/m^(2))is promising for applications in information sensing,storage,and processing,and thus sparking widespread research interest.Exploring candidate material systems with nanoscale size and easily tunable properties is a key for realizing practical topological magnetism-based spintronic devices.Here,we propose a class of ultrathin heterostructures,Fe/Bi_(2)O_(2)X(X=S,Se,Te)by deposing metal Fe on quasi-two-dimensional(2D)bismuth oxychalcogenides Bi_(2)O_(2)X(X=S,Se,Te)with excellent ferroelectric/ferroelastic properties.Large Dzyaloshinskii–Moriya interaction(DMI)and topological magnetism can be realized.Our atomistic spin dynamics simulations demonstrate that field-free vortex–antivortex loops and sub-10 nm skyrmions exist in Fe/Bi_(2)O_(2)S and Fe/Bi_(2)O_(2)Se interfaces,respectively.These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces,which is extremely vital for spintronics applications.展开更多
We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals grown by large-temperature-gradient chemical vapor transport method.It...We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals grown by large-temperature-gradient chemical vapor transport method.It is found that the ferromagnetic MnSb_(2)Te_(4) changes to antiferromagnetism with Bi doping when x≥0.25.Further analysis implies that the occupations of Mn ions at Sb/Bi site Mn_(Sb/Bi) and Mn site Mn_(Mn) have a strong influence on the magnetic ground states of these systems.With the decrease of Mn_(Mn) increase of Mn_(Sb/Bi),the system will favor the ferromagnetic ground state.In addition,the rapid decrease of T_(C/N) with increasing Bi content when x ≤0.25 and the insensitivity of T_(N) to x when x> 0.25 suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.展开更多
After the discovery of the ARECh_(2)(A=alkali or monovalent ions,RE=rare-earth,Ch=chalcogen)triangular lattice quantum spin liquid(QSL)family,a series of its oxide,sulfide,and selenide counterparts has been consistent...After the discovery of the ARECh_(2)(A=alkali or monovalent ions,RE=rare-earth,Ch=chalcogen)triangular lattice quantum spin liquid(QSL)family,a series of its oxide,sulfide,and selenide counterparts has been consistently reported and extensively investigated.While KErTe_(2) represents the initial synthesized telluride member,preserving its triangular spin lattice,it was anticipated that the substantial tellurium ions could impart more pronounced magnetic attributes and electronic structures to this material class.This study delves into the magnetism of KErTe_(2) at finite temperatures through magnetization and electron spin resonance(ESR)measurements.Based on the angular momentum J after spin-orbit coupling(SOC)and symmetry analysis,we obtain the magnetic effective Hamiltonian to describe the magnetism of Er^(3+)in R3m space group.Applying the mean-field approximation to the Hamiltonian,we can simulate the magnetization and magnetic heat capacity of KErTe_(2) in paramagnetic state and determine the crystalline electric field(CEF)parameters and partial exchange interactions.The relatively narrow energy gaps between the CEF ground state and excited states exert a significant influence on the magnetism.For example,small CEF excitations can result in a significant broadening of the ESR linewidth at 2 K.For the fitted exchange interactions,although the values are small,given a large angular momentum J=15/2 after SOC,they still have a noticeable effect at finite temperatures.Notably,the heat capacity data under different magnetic fields along the𝑐axis direction also roughly match our calculated results,further validating the reliability of our analytical approach.These derived parameters serve as crucial tools for future investigations into the ground state magnetism of KErTe_(2).The findings presented herein lay a foundation for exploration of the intricate magnetism within the triangular-lattice delafossite family.展开更多
Recent experimental and theoretical work has focused on two-dimensional van der Waals(2D vdW)magnets due to their potential applications in sensing and spintronics devises.In measurements of these emerging materials,c...Recent experimental and theoretical work has focused on two-dimensional van der Waals(2D vdW)magnets due to their potential applications in sensing and spintronics devises.In measurements of these emerging materials,conventional magnetometry often encounters challenges in characterizing the magnetic properties of small-sized vdW materials,especially for antiferromagnets with nearly compensated magnetic moments.Here,we investigate the magnetism of 2D antiferromagnet CrPS_(4)with a thickness of 8nm by using dynamic cantilever magnetometry(DCM).展开更多
Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For th...Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For the sample with active Cu as the top electrode,the formation and rupture of metallic Cu conductive filaments can explain the resistive switching behavior;for the other samples,the generation and annihilation of nitrogen vacancies under the electric stimuli may contribute to the occurrence of resistive switching.Taking advantage of the formed and broken Co-N bonds during resistive switching,the saturation magnetization of the BN-Co films can be modulated.Thus,it investigated the resistive switching behavior of BN and BN-Co materials in this work.Similar to that of oxide materials,the resistive switching behaviors of the nitrides may be attributed to the movement of cations or anions within the dielectric or electrodes during the application of voltage.Additionally,ion migration may lead to the formation or breaking of Co-N bonds,which can effectively regulate the magnetism of BN-Co materials.This study extends resistive switching materials to nitrides,enabling the regulation of magnetism along with resistance changes,thus providing insights for the design of novel voltage-controlled magnetic devices and achieving multi-functionality.展开更多
The electronic structures and magnetism of Fe nanowires along the [110] direction on Cu（001） and Ag（001） [Fe（nw）/Cu（001） and Fe（nw）/Ag（001）] are investigated by using the all-electron full-potential linear...The electronic structures and magnetism of Fe nanowires along the [110] direction on Cu（001） and Ag（001） [Fe（nw）/Cu（001） and Fe（nw）/Ag（001）] are investigated by using the all-electron full-potential linearized augmented plane wave method in the generalized gradient approximation. It is found that the magnetic moment of Fe atom for the Fe（nw）/Cu（001） is 2.99#B, which is slightly smaller than that （3.02μB） for the Fe（nw）/Ag（001） but much larger than that （2.22μB） for the bcc iron. The great enhancement of magnetic moment in the Fe nanowires can be explained by the Fe d-band narrowing and enhancement of the spin-splitting due to a reduction in coordination number, From the calculated spin-polarized layer-projected density of states, it is found that the Fe 3d-states are strongly hybridized with the adjacent Cu 3d-states in the Fe（nw）/Cu（001）, and there exists a strong hybridization between the Fe sp-and the adjacent Ag 4d-states in the Fe（nw）/Ag（001）.展开更多
We predict that the recently discovered quasi-one-dimensional superconductors, A2 Cr3As3 （A=K, Rb）, possess strong frustrated magnetic fluctuations and are nearby a novel in-out co-planar magnetic ground state. The ...We predict that the recently discovered quasi-one-dimensional superconductors, A2 Cr3As3 （A=K, Rb）, possess strong frustrated magnetic fluctuations and are nearby a novel in-out co-planar magnetic ground state. The frustrated magnetism is very sensitive to the c-axis lattice constant and can thus be suppressed by increasing pressure. Our results qualitatively explain strong non-Fermi liquid behaviors observed in the normal state of the superconductors as the intertwining between the magnetism and superconductivity can create a large quantum critical region in quasi-one-dimensional systems and also suggest that the materials share similar phase diagrams and superconducting mechanism with other unconventional superconductors, such as cuprates and iron-based superconductors.展开更多
Heavily Mn-doped SiGe thin films were grown by radio frequency magnetron sputtering and then treated by postgrowth thermal annealing.Structural characterizations reveal the coexistence of Mn-diluted SiGe crystals and ...Heavily Mn-doped SiGe thin films were grown by radio frequency magnetron sputtering and then treated by postgrowth thermal annealing.Structural characterizations reveal the coexistence of Mn-diluted SiGe crystals and Mn-rich nanoclusters in the annealed films.Magnetic measurements indicate the ferromagnetic ordering of the annealed samples above room temperature.The data suggest that the ferromagnetism is probably mainly contributed by the Ge-rich nanoclusters and partially contributed by the tensile-strained Mn-diluted SiGe crystals.The results may be useful for room temperature spintronic applications based on group IV semiconductors.展开更多
The Permian coal in southwest China contains highest sulfur among the Chinese coal .Compositional variations of sumir in coal are mainly controlled by palaogeographital environmentsduring peat accumulation. High organ...The Permian coal in southwest China contains highest sulfur among the Chinese coal .Compositional variations of sumir in coal are mainly controlled by palaogeographital environmentsduring peat accumulation. High organic sulfur coal is formed in peat swamp developing in tidal flat of limited carbonate platform, and it is provided with especial petrologital and geochemical characteristics, and its organoschr-containing compounds are mainly thiophene series. The macroscopitaland microscopical shapes or types of pyrites in Late Permisn coal are diversined. Bituminous coal and anthracite are diamagnetic, but the pyrites are paramagnetic. The magnetic susceptibility oftbe pyrites is depended on the content of paramagnatic elements associnted with pyrites.展开更多
We perform a detailed investigation of the new ＇breathing＇ pyrochlore compound LiInCr4O8 through Rh substi- tution with measurements of magnetic susceptibility, specific heat, and x-ray powder diffraction. The antif...We perform a detailed investigation of the new ＇breathing＇ pyrochlore compound LiInCr4O8 through Rh substi- tution with measurements of magnetic susceptibility, specific heat, and x-ray powder diffraction. The antiferro- magnetic phase of LiInCr4O8 is found to be slowly suppressed with increasing Rh, up to the critical concentration of x = 0.1 where the antiferromagnetic phase is still observed with the peak in specific heat Tp = 12.5 K, slightly lower than Tp =14.3 K for the x = 0 compound. From tile measurements of magnetization we also uncover evidence that substitution increases the amount of frustration. Comparisons are made with the LiGayIn1-yCr4O8 system as well as other frustrated pyrochlore-related materials and comparable amounts of frustration are found. The results of this work show that the engineered breathing pyrochlores present an important method to further understand the complex magnetism in frustrated systems.展开更多
Ceria(CeO_2) nanocubes were synthesized by a hydrothermal method and weak ferromagnetism was observed in room temperature. After ultraviolet irradiation, the saturation magnetization was significantly enhanced from*3....Ceria(CeO_2) nanocubes were synthesized by a hydrothermal method and weak ferromagnetism was observed in room temperature. After ultraviolet irradiation, the saturation magnetization was significantly enhanced from*3.18×10^(-3) to *1.89×10^(-2) emug^(-1). This is due to the increase of oxygen vacancies in CeO_2 structure which was confirmed by X-ray photoelectron spectra. The first-principle calculation with Vienna ab-initio simulation package was used to illustrate the enhanced ferromagnetism mechanism after calculating the density of states(DOSs) and partial density of states(PDOSs) of CeO_2 without and with different oxygen vacancies. It was found that the increase of oxygen vacancies will enlarge the PDOSs of Ce 4f orbital and DOSs. Two electrons in one oxygen vacancy are respectively excited to 4f orbital of two Ce atoms neighboring the vacancy, making these electron spin directions on 4f orbitals of these two Ce atoms parallel. This superexchange interaction leads to the formation of ferromagnetism in CeO_2 at room temperature. Our work indicates that ultraviolet irradiation is an effective method to enhance the magnetism of CeO_2 nanocube, and the firstprinciple calculation can understand well the enhanced magnetism.展开更多
The ground-state configurations of the Nbn （n = 2-11） clusters are studied through the first-principles calculations. It is found that niobium clusters （n = 2-11） tend to form compact structures with low symmetry....The ground-state configurations of the Nbn （n = 2-11） clusters are studied through the first-principles calculations. It is found that niobium clusters （n = 2-11） tend to form compact structures with low symmetry. The clusters with 4, 8 and 10 atoms axe found to be magic and have relatively large highest occupied-lowest unoccupied molecular orbital （HOMO-LUMO） gaps. The Nbn clusters possess low magnetic moments, which exhibit an odd-even oscillational character. The analyses of calculated electronic density and population of the lowest-energy niobium clusters for n =2, 3, 5, 7, 9, 11 show that the total magnetic moments of Nbn originate mainly from a few Nb atoms with longer spacings between them in most cases, while they are located on two Nb atoms for n = 2, 3, 5. The total magnetic moments come mainly from the 4d local moments but with the exception of the Nb5 cluster.展开更多
We investigate the effects of strain on the electronic and magnetic properties of ReS2 monolayer with sulfur vacancies using density functional theory.Unstrained ReS2 monolayer with monosulfur vacancy（Vs） and disulf...We investigate the effects of strain on the electronic and magnetic properties of ReS2 monolayer with sulfur vacancies using density functional theory.Unstrained ReS2 monolayer with monosulfur vacancy（Vs） and disulfur vacancy（V（2S））both are nonmagnetic.However,as strain increases to 8%,VS-doped ReS2 monolayer appears a magnetic half-metal behavior with zero total magnetic moment.In particular,for V（2S）-doped ReS2 monolayer,the system becomes a magnetic semiconductor under 6%strain,in which Re atoms at vicinity of vacancy couple anti-ferromagnetically with each other,and continues to show a ferromagnetic metal characteristic with total magnetic moment of 1.60μb under 7%strain.Our results imply that the strain-manipulated ReS2 monolayer with VS and V（2S） can be a possible candidate for new spintronic applications.展开更多
It has been demonstrated that the zigzag honeycomb nanoribbons exhibit an intriguing edge magnetism. Here the effect of the anisotropy on the edge magnetism in zigzag honeycomb nanoribbons is investigated using two ki...It has been demonstrated that the zigzag honeycomb nanoribbons exhibit an intriguing edge magnetism. Here the effect of the anisotropy on the edge magnetism in zigzag honeycomb nanoribbons is investigated using two kinds of large-scale quantum Monte Carlo simulations. The anisotropy in zigzag honeycomb nanoribbons is characterized by the ratios of nearest-neighbor hopping integrals t_1 in one direction and t_2 in another direction. Considering the electron-electron correlation, it is shown that the edge ferromagnetism could be enhanced greatly as t_2/|t_1|increases from 1 to 3, which not only presents an avenue for the control of this magnetism but is also useful for exploring further novel magnetism in new nano-scale materials.展开更多
HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combina...HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combination of magnetization under external hydrostatic pressure and thermal conductivity at various magnetic fields. Upon applying pressure up to 10 kbar at 1 kOe, while the magnitude of magnetization reduces progressively, the AFM ordering temperature TN enhances concomitantly at a rate of about 1.5 K/kbar. Strikingly, at lO kOe the field polarized FM state is found to be driven readily back to an AFM one even at only 5kbar. In addition, the thermal conductivity exhibits drastic increments at various fields in the temperature range with strong spin fluctuations, reaching about 30% at 50 kOe. Consequently, the results give new experimental evidence of spin-lattice coupling. Apart from the colossal magnetoeapacitance and colossal magnetoresistance reported previously, the findings here may enable new promising functionalities for potential applications.展开更多
Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturatio...Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturation magnetization σs 0.2-0.3 A.M2/kg, being consistent with the feature of antiferromagnetic α-Fe2O3. While the samples of group B display strong magnetism with susceptibility 10-1-10-2 and σs 1.7-12 A.M2 /kg. Mossbauer spectra of the samples were investigated at room temperature in an external magnetic field. It is suggested there is the y - Fe2O3 phase in the group B according to the relative intensities of spectra I(2,5)/I(3,4). This was proved by the Mossbauer spectra for the mixed samples A with γ-Fe2O3 at various contents and by measuring the dependence of specific saturation magnetization on temperature for the samples of group B.展开更多
Nanomagnetism is the origin of many unique properties in magnetic nanomaterials that can be used as building blocks in information technology, spintronics, and biomedicine. Progresses in nanomagnetic principles, disti...Nanomagnetism is the origin of many unique properties in magnetic nanomaterials that can be used as building blocks in information technology, spintronics, and biomedicine. Progresses in nanomagnetic principles, distinct magnetic nanostructures, and the biomedical applications of nanomagnetism are summarized.展开更多
First-principle calculations reveal that the configuration system of hexagonal boron nitride （h-BN） monolayer with triangular vacancy can induce obvious magnetism, contrary to that of the nonmagnetic pristine boron ...First-principle calculations reveal that the configuration system of hexagonal boron nitride （h-BN） monolayer with triangular vacancy can induce obvious magnetism, contrary to that of the nonmagnetic pristine boron nitride monolayer. Interestingly, the h-BN with boron atom vacancy （VB-BN） displays metallic behavior with a total magetic moment being 0.46μB per cell, while the h-BN with nitrogen atom vacancy （VN-BN） presents a half-metallic characteristic with a total magnetic moment being 1.0μB per cell. Remarkably, piezoelectric stress coefficient ell of the VN-BN is about 1.5 times larger than that of pristine h-BN. Furthermore, piezoelectric strain coefficient dll （12.42 μm/V） of the VN-BN is 20 times larger than that of pristine h-BN and also one order of magnitude larger than the value for the h-MoS2 monolayer, which is mainly due to the spin-down electronic state in the VN-BN system. Our study demonstrates that the nitrogen atom vacancies can be an efficient route to tailoring the magnetic and piezoelectric properties of h-BN monolayer, which have promising performances for potential applications in nano-electromechanical systems （NEMS） and nanoscale electronics devices.展开更多
We discuss a new class of phenomena that we call ＂spin plasmonics＂. It is motivated by three different recent trends of physics research： （i） spintronics, （ii） plasmonics, and （iii） topological properties as ...We discuss a new class of phenomena that we call ＂spin plasmonics＂. It is motivated by three different recent trends of physics research： （i） spintronics, （ii） plasmonics, and （iii） topological properties as is exemplified by the quantized Hall effect. This involves the physics of the ＂magnetic surface plasmon＂ （MSP） which provides for an analog of the edge states discussed in the quantized Hall effect. Their properties can be easily tuned by an external magnetic field. They are coupled to the electromagnetic field and can be injected into metallic structures and induce spin and charge currents and hold the promise of miniturization of nonreciprocal devices.展开更多
基金Project supported by the National Key R&D Program of China (Grant Nos.2022YFA1403203 and 2021YFA1600201)the National Natural Science Foundation of China (Grant Nos.11974356 and 12274414)+1 种基金the Joint Funds of the National Natural Science Foundation of Chinathe Chinese Academy of Sciences Large-Scale Scientific Facility (Grant No.U1932216)。
文摘Group IV element Pb has been selected as the dopant to dope at the Sr site of Sr_(2)IrO_(4). It is exciting to find that the single-phase crystal structure could be maintained with a high Pb doping level of up to x=0.3 in Sr_(2-x)Pb_(x)IrO_(4). The mapping data obtained from energy-dispersive x-ray spectroscopy analyses give solid evidence that the Pb ions are uniformly distributed in the Sr_(2)IrO_(4) matrix. The incorporation of Pb leads to a moderate depression of the canted antiferromagnetic ordering state. The electrical conductivity could be greatly enhanced when the Pb doping content is higher than x=0.2.The present results give a fresh material base to explore new physics in doped Sr_(2)IrO_(4) systems.
基金the National Key Research and Development Program of China(Grant Nos.2022YFA1405100,2022YFA1403601,2020AAA0109005,and 2023YFB4502100)the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C01053)+1 种基金the National Natural Science Foundation of China(Grant Nos.12174405,12204497,12327806,and 62074063)Shenzhen Science and Technology Program(Grant No.JCYJ20220818103410022).
文摘Topological magnetism with strong robustness,nanoscale dimensions and ultralow driving current density(106 A/m^(2))is promising for applications in information sensing,storage,and processing,and thus sparking widespread research interest.Exploring candidate material systems with nanoscale size and easily tunable properties is a key for realizing practical topological magnetism-based spintronic devices.Here,we propose a class of ultrathin heterostructures,Fe/Bi_(2)O_(2)X(X=S,Se,Te)by deposing metal Fe on quasi-two-dimensional(2D)bismuth oxychalcogenides Bi_(2)O_(2)X(X=S,Se,Te)with excellent ferroelectric/ferroelastic properties.Large Dzyaloshinskii–Moriya interaction(DMI)and topological magnetism can be realized.Our atomistic spin dynamics simulations demonstrate that field-free vortex–antivortex loops and sub-10 nm skyrmions exist in Fe/Bi_(2)O_(2)S and Fe/Bi_(2)O_(2)Se interfaces,respectively.These results provide a possible strategy to tailor topological magnetism in ultrathin magnets/2D materials interfaces,which is extremely vital for spintronics applications.
基金Project supported by the Beijing Natural Science Foundation (Grant No. Z200005)the National Key R&D Program of China (Grant Nos. 2022YFA1403800 and 2023YFA1406500)+1 种基金the National Natural Science Foundation of China (Grant No. 12274459)Collaborative Research Project of Laboratory for Materials and Structures, Institute of Innovative Research, Tokyo Institute of Technology。
文摘We investigate the evolution of magnetic properties as well as the content and distribution of Mn for Mn(Sb_(1-x)Bi_(x))_(2)Te_(4) single crystals grown by large-temperature-gradient chemical vapor transport method.It is found that the ferromagnetic MnSb_(2)Te_(4) changes to antiferromagnetism with Bi doping when x≥0.25.Further analysis implies that the occupations of Mn ions at Sb/Bi site Mn_(Sb/Bi) and Mn site Mn_(Mn) have a strong influence on the magnetic ground states of these systems.With the decrease of Mn_(Mn) increase of Mn_(Sb/Bi),the system will favor the ferromagnetic ground state.In addition,the rapid decrease of T_(C/N) with increasing Bi content when x ≤0.25 and the insensitivity of T_(N) to x when x> 0.25 suggest that the main magnetic interaction may change from the Ruderman-Kittel-Kasuya-Yosida type at low Bi doping region to the van-Vleck type in high Bi doped samples.
基金supported by the National Science Foundation of China(Grant Nos.U1932215 and 12274186)the National Key Research and Development Program of China(Grant No.2022YFA1402704)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33010100)the Synergetic Extreme Condition User Facility(SECUF)。
文摘After the discovery of the ARECh_(2)(A=alkali or monovalent ions,RE=rare-earth,Ch=chalcogen)triangular lattice quantum spin liquid(QSL)family,a series of its oxide,sulfide,and selenide counterparts has been consistently reported and extensively investigated.While KErTe_(2) represents the initial synthesized telluride member,preserving its triangular spin lattice,it was anticipated that the substantial tellurium ions could impart more pronounced magnetic attributes and electronic structures to this material class.This study delves into the magnetism of KErTe_(2) at finite temperatures through magnetization and electron spin resonance(ESR)measurements.Based on the angular momentum J after spin-orbit coupling(SOC)and symmetry analysis,we obtain the magnetic effective Hamiltonian to describe the magnetism of Er^(3+)in R3m space group.Applying the mean-field approximation to the Hamiltonian,we can simulate the magnetization and magnetic heat capacity of KErTe_(2) in paramagnetic state and determine the crystalline electric field(CEF)parameters and partial exchange interactions.The relatively narrow energy gaps between the CEF ground state and excited states exert a significant influence on the magnetism.For example,small CEF excitations can result in a significant broadening of the ESR linewidth at 2 K.For the fitted exchange interactions,although the values are small,given a large angular momentum J=15/2 after SOC,they still have a noticeable effect at finite temperatures.Notably,the heat capacity data under different magnetic fields along the𝑐axis direction also roughly match our calculated results,further validating the reliability of our analytical approach.These derived parameters serve as crucial tools for future investigations into the ground state magnetism of KErTe_(2).The findings presented herein lay a foundation for exploration of the intricate magnetism within the triangular-lattice delafossite family.
基金supported by the National Key R&D Program of China(Grant No.2022YFA1602602)the National Natural Science Foundation of China(Grant Nos.12122411 and 12474053)+4 种基金CAS Project for Young Scientists in Basic Research(Grant No.YSBR-084)HFIPS Director’s Fund(Grant Nos.2023BR,YZJJ-GGZX-2022-03,and YZJJ202403TS)HFIPS Director’s Fud(Grant No.BJPY2021B05)the Basic Research Program of the Chinese Academy of Sciences Based on Major Scientific Infrastructures(Grant No.JZHKYPT-2021-08)the High Magnetic Field Laboratory of Anhui Province(Grant No.AHHM-FX2020-02)。
文摘Recent experimental and theoretical work has focused on two-dimensional van der Waals(2D vdW)magnets due to their potential applications in sensing and spintronics devises.In measurements of these emerging materials,conventional magnetometry often encounters challenges in characterizing the magnetic properties of small-sized vdW materials,especially for antiferromagnets with nearly compensated magnetic moments.Here,we investigate the magnetism of 2D antiferromagnet CrPS_(4)with a thickness of 8nm by using dynamic cantilever magnetometry(DCM).
文摘Nanostructured BN and BN-Co films with Cu,Co,Au as the top electrodes,and Pt as the bottom electrodes were grown by magnetron sputtering.Both BN samples and BN-Co ones show bipolar resistive switching behaviors.For the sample with active Cu as the top electrode,the formation and rupture of metallic Cu conductive filaments can explain the resistive switching behavior;for the other samples,the generation and annihilation of nitrogen vacancies under the electric stimuli may contribute to the occurrence of resistive switching.Taking advantage of the formed and broken Co-N bonds during resistive switching,the saturation magnetization of the BN-Co films can be modulated.Thus,it investigated the resistive switching behavior of BN and BN-Co materials in this work.Similar to that of oxide materials,the resistive switching behaviors of the nitrides may be attributed to the movement of cations or anions within the dielectric or electrodes during the application of voltage.Additionally,ion migration may lead to the formation or breaking of Co-N bonds,which can effectively regulate the magnetism of BN-Co materials.This study extends resistive switching materials to nitrides,enabling the regulation of magnetism along with resistance changes,thus providing insights for the design of novel voltage-controlled magnetic devices and achieving multi-functionality.
文摘The electronic structures and magnetism of Fe nanowires along the [110] direction on Cu（001） and Ag（001） [Fe（nw）/Cu（001） and Fe（nw）/Ag（001）] are investigated by using the all-electron full-potential linearized augmented plane wave method in the generalized gradient approximation. It is found that the magnetic moment of Fe atom for the Fe（nw）/Cu（001） is 2.99#B, which is slightly smaller than that （3.02μB） for the Fe（nw）/Ag（001） but much larger than that （2.22μB） for the bcc iron. The great enhancement of magnetic moment in the Fe nanowires can be explained by the Fe d-band narrowing and enhancement of the spin-splitting due to a reduction in coordination number, From the calculated spin-polarized layer-projected density of states, it is found that the Fe 3d-states are strongly hybridized with the adjacent Cu 3d-states in the Fe（nw）/Cu（001）, and there exists a strong hybridization between the Fe sp-and the adjacent Ag 4d-states in the Fe（nw）/Ag（001）.
基金Supported by the National Basic Research Program of China under Grant Nos 2010CB922904,2012CV821400 and2015CB921300the National Natural Science Foundation of China under Grant Nos 1190024,11175248 and 11104339the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No XDB07000000
文摘We predict that the recently discovered quasi-one-dimensional superconductors, A2 Cr3As3 （A=K, Rb）, possess strong frustrated magnetic fluctuations and are nearby a novel in-out co-planar magnetic ground state. The frustrated magnetism is very sensitive to the c-axis lattice constant and can thus be suppressed by increasing pressure. Our results qualitatively explain strong non-Fermi liquid behaviors observed in the normal state of the superconductors as the intertwining between the magnetism and superconductivity can create a large quantum critical region in quasi-one-dimensional systems and also suggest that the materials share similar phase diagrams and superconducting mechanism with other unconventional superconductors, such as cuprates and iron-based superconductors.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFB0405702)the National Natural Science Foundation of China(Grant No.51671137).
文摘Heavily Mn-doped SiGe thin films were grown by radio frequency magnetron sputtering and then treated by postgrowth thermal annealing.Structural characterizations reveal the coexistence of Mn-diluted SiGe crystals and Mn-rich nanoclusters in the annealed films.Magnetic measurements indicate the ferromagnetic ordering of the annealed samples above room temperature.The data suggest that the ferromagnetism is probably mainly contributed by the Ge-rich nanoclusters and partially contributed by the tensile-strained Mn-diluted SiGe crystals.The results may be useful for room temperature spintronic applications based on group IV semiconductors.
文摘The Permian coal in southwest China contains highest sulfur among the Chinese coal .Compositional variations of sumir in coal are mainly controlled by palaogeographital environmentsduring peat accumulation. High organic sulfur coal is formed in peat swamp developing in tidal flat of limited carbonate platform, and it is provided with especial petrologital and geochemical characteristics, and its organoschr-containing compounds are mainly thiophene series. The macroscopitaland microscopical shapes or types of pyrites in Late Permisn coal are diversined. Bituminous coal and anthracite are diamagnetic, but the pyrites are paramagnetic. The magnetic susceptibility oftbe pyrites is depended on the content of paramagnatic elements associnted with pyrites.
基金Supported by the Ministry of Science and Technology under Grant No 2016YFA0300503
文摘We perform a detailed investigation of the new ＇breathing＇ pyrochlore compound LiInCr4O8 through Rh substi- tution with measurements of magnetic susceptibility, specific heat, and x-ray powder diffraction. The antiferro- magnetic phase of LiInCr4O8 is found to be slowly suppressed with increasing Rh, up to the critical concentration of x = 0.1 where the antiferromagnetic phase is still observed with the peak in specific heat Tp = 12.5 K, slightly lower than Tp =14.3 K for the x = 0 compound. From tile measurements of magnetization we also uncover evidence that substitution increases the amount of frustration. Comparisons are made with the LiGayIn1-yCr4O8 system as well as other frustrated pyrochlore-related materials and comparable amounts of frustration are found. The results of this work show that the engineered breathing pyrochlores present an important method to further understand the complex magnetism in frustrated systems.
基金supported by the National High Technology Research and Development Program(863 program)of China(2015AA034801)NSFC(11204388+2 种基金51402112)the Fundamental Research Funds for the Central Universities(CQDXWL-2014-001 and CQDXWL-2013-012)the large-scale equipment sharing fund of Chongqing University
文摘Ceria(CeO_2) nanocubes were synthesized by a hydrothermal method and weak ferromagnetism was observed in room temperature. After ultraviolet irradiation, the saturation magnetization was significantly enhanced from*3.18×10^(-3) to *1.89×10^(-2) emug^(-1). This is due to the increase of oxygen vacancies in CeO_2 structure which was confirmed by X-ray photoelectron spectra. The first-principle calculation with Vienna ab-initio simulation package was used to illustrate the enhanced ferromagnetism mechanism after calculating the density of states(DOSs) and partial density of states(PDOSs) of CeO_2 without and with different oxygen vacancies. It was found that the increase of oxygen vacancies will enlarge the PDOSs of Ce 4f orbital and DOSs. Two electrons in one oxygen vacancy are respectively excited to 4f orbital of two Ce atoms neighboring the vacancy, making these electron spin directions on 4f orbitals of these two Ce atoms parallel. This superexchange interaction leads to the formation of ferromagnetism in CeO_2 at room temperature. Our work indicates that ultraviolet irradiation is an effective method to enhance the magnetism of CeO_2 nanocube, and the firstprinciple calculation can understand well the enhanced magnetism.
基金Project supported by the Program for Science & Technology Innovation Talents in Universities of Henan Province, China (Grant No 2009HASTIT003)the Natural Science Foundation of Henan University, China (Grant Nos 07ZRZD005 and 07YBZR046)the Foundation of Science and Technology Department of Henan Province, China (Grant No 082300410010)
文摘The ground-state configurations of the Nbn （n = 2-11） clusters are studied through the first-principles calculations. It is found that niobium clusters （n = 2-11） tend to form compact structures with low symmetry. The clusters with 4, 8 and 10 atoms axe found to be magic and have relatively large highest occupied-lowest unoccupied molecular orbital （HOMO-LUMO） gaps. The Nbn clusters possess low magnetic moments, which exhibit an odd-even oscillational character. The analyses of calculated electronic density and population of the lowest-energy niobium clusters for n =2, 3, 5, 7, 9, 11 show that the total magnetic moments of Nbn originate mainly from a few Nb atoms with longer spacings between them in most cases, while they are located on two Nb atoms for n = 2, 3, 5. The total magnetic moments come mainly from the 4d local moments but with the exception of the Nb5 cluster.
基金Project supported by the National Natural Science Foundation of China(Grant No.11547030)
文摘We investigate the effects of strain on the electronic and magnetic properties of ReS2 monolayer with sulfur vacancies using density functional theory.Unstrained ReS2 monolayer with monosulfur vacancy（Vs） and disulfur vacancy（V（2S））both are nonmagnetic.However,as strain increases to 8%,VS-doped ReS2 monolayer appears a magnetic half-metal behavior with zero total magnetic moment.In particular,for V（2S）-doped ReS2 monolayer,the system becomes a magnetic semiconductor under 6%strain,in which Re atoms at vicinity of vacancy couple anti-ferromagnetically with each other,and continues to show a ferromagnetic metal characteristic with total magnetic moment of 1.60μb under 7%strain.Our results imply that the strain-manipulated ReS2 monolayer with VS and V（2S） can be a possible candidate for new spintronic applications.
基金Supported by the National Natural Science Foundation of China under Grant No 11774033the Beijing Natural Science Foundation under Grant No 1192011
文摘It has been demonstrated that the zigzag honeycomb nanoribbons exhibit an intriguing edge magnetism. Here the effect of the anisotropy on the edge magnetism in zigzag honeycomb nanoribbons is investigated using two kinds of large-scale quantum Monte Carlo simulations. The anisotropy in zigzag honeycomb nanoribbons is characterized by the ratios of nearest-neighbor hopping integrals t_1 in one direction and t_2 in another direction. Considering the electron-electron correlation, it is shown that the edge ferromagnetism could be enhanced greatly as t_2/|t_1|increases from 1 to 3, which not only presents an avenue for the control of this magnetism but is also useful for exploring further novel magnetism in new nano-scale materials.
基金Supported by the National Natural Science Foundation of China under Grant Nos U1332143 and 11574323
文摘HgCr2S4 is a typical compound manifesting competing ferromagnetic （FM） and antiferromagnetic （AFM） exchanges as well as strong spin-lattice coupling. Here we study these effects by intentionally choosing a combination of magnetization under external hydrostatic pressure and thermal conductivity at various magnetic fields. Upon applying pressure up to 10 kbar at 1 kOe, while the magnitude of magnetization reduces progressively, the AFM ordering temperature TN enhances concomitantly at a rate of about 1.5 K/kbar. Strikingly, at lO kOe the field polarized FM state is found to be driven readily back to an AFM one even at only 5kbar. In addition, the thermal conductivity exhibits drastic increments at various fields in the temperature range with strong spin fluctuations, reaching about 30% at 50 kOe. Consequently, the results give new experimental evidence of spin-lattice coupling. Apart from the colossal magnetoeapacitance and colossal magnetoresistance reported previously, the findings here may enable new promising functionalities for potential applications.
文摘Six kinds of typical commercial Fe2O3 were sampled and divided into two groups A and B. according to the magnetic measurement results. The samples of group A are of susceptibility about 10-4 and the specific saturation magnetization σs 0.2-0.3 A.M2/kg, being consistent with the feature of antiferromagnetic α-Fe2O3. While the samples of group B display strong magnetism with susceptibility 10-1-10-2 and σs 1.7-12 A.M2 /kg. Mossbauer spectra of the samples were investigated at room temperature in an external magnetic field. It is suggested there is the y - Fe2O3 phase in the group B according to the relative intensities of spectra I(2,5)/I(3,4). This was proved by the Mossbauer spectra for the mixed samples A with γ-Fe2O3 at various contents and by measuring the dependence of specific saturation magnetization on temperature for the samples of group B.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB934601)the National Natural Science Foundation of China(Grant Nos.51125001 and 51172005)+1 种基金the Natural Science Foundation of Beijing,China(Grant No.2122022)the Doctoral Program,China(Grant No.20120001110078)
文摘Nanomagnetism is the origin of many unique properties in magnetic nanomaterials that can be used as building blocks in information technology, spintronics, and biomedicine. Progresses in nanomagnetic principles, distinct magnetic nanostructures, and the biomedical applications of nanomagnetism are summarized.
基金Project supported by the National Natural Science Foundation of China(Grant No.11474123)the Natural Science Foundation of Jilin Province,China(Grant No.20170101154JC)
文摘First-principle calculations reveal that the configuration system of hexagonal boron nitride （h-BN） monolayer with triangular vacancy can induce obvious magnetism, contrary to that of the nonmagnetic pristine boron nitride monolayer. Interestingly, the h-BN with boron atom vacancy （VB-BN） displays metallic behavior with a total magetic moment being 0.46μB per cell, while the h-BN with nitrogen atom vacancy （VN-BN） presents a half-metallic characteristic with a total magnetic moment being 1.0μB per cell. Remarkably, piezoelectric stress coefficient ell of the VN-BN is about 1.5 times larger than that of pristine h-BN. Furthermore, piezoelectric strain coefficient dll （12.42 μm/V） of the VN-BN is 20 times larger than that of pristine h-BN and also one order of magnitude larger than the value for the h-MoS2 monolayer, which is mainly due to the spin-down electronic state in the VN-BN system. Our study demonstrates that the nitrogen atom vacancies can be an efficient route to tailoring the magnetic and piezoelectric properties of h-BN monolayer, which have promising performances for potential applications in nano-electromechanical systems （NEMS） and nanoscale electronics devices.
基金supported by the National Basic Research Program of China(Grant No.2011CB922004)the National Natural Science Foundation of China(Grant No.11174059)
文摘We discuss a new class of phenomena that we call ＂spin plasmonics＂. It is motivated by three different recent trends of physics research： （i） spintronics, （ii） plasmonics, and （iii） topological properties as is exemplified by the quantized Hall effect. This involves the physics of the ＂magnetic surface plasmon＂ （MSP） which provides for an analog of the edge states discussed in the quantized Hall effect. Their properties can be easily tuned by an external magnetic field. They are coupled to the electromagnetic field and can be injected into metallic structures and induce spin and charge currents and hold the promise of miniturization of nonreciprocal devices.
