Due to the upcoming demands of next-generation electronic/magnetoelectronic devices with low-energy consumption,emerging correlated materials（such as superconductors,topological insulators and manganites） are one of...Due to the upcoming demands of next-generation electronic/magnetoelectronic devices with low-energy consumption,emerging correlated materials（such as superconductors,topological insulators and manganites） are one of the highly promising candidates for the applications.For the past decades,manganites have attracted great interest due to the colossal magnetoresistance effect,charge-spin-orbital ordering,and electronic phase separation.However,the incapable of deterministic control of those emerging low-dimensional spin structures at ambient condition restrict their possible applications.Therefore,the understanding and control of the dynamic behaviors of spin order parameters at nanoscale in manganites under external stimuli with low energy consumption,especially at room temperature is highly desired.In this review,we collected recent major progresses of nanoscale control of spin structures in manganites at low dimension,especially focusing on the control of their phase boundaries,domain walls as well as the topological spin structures（e.g.,skyrmions）.In addition,capacitor-based prototype spintronic devices are proposed by taking advantage of the above control methods in manganites.This capacitor-based structure may provide a new platform for the design of future spintronic devices with low-energy consumption.展开更多
We discuss the nucleon spin structure function g<SUB>1</SUB> and the difference between the proton and neutron targets , based on quark model calculation. Quark-hadron duality for the nucleon spin structur...We discuss the nucleon spin structure function g<SUB>1</SUB> and the difference between the proton and neutron targets , based on quark model calculation. Quark-hadron duality for the nucleon spin structure function is also analyzed. Effects of the Δ(1232) and Roper P<SUB>11</SUB>(1440) resonances on the spin structure function and on the difference are mentioned. The results of different models for the Roper resonance are also addressed.展开更多
By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-...By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.展开更多
Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×...Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×→B）and→JII≡fd3x（∈0→E×→A⊥＋∈0Ei→τ× A⊥i）.Notably, at the classical level, →JI gives an exactly null result while →JI gives a finite value. This suggests that Jn leads to a simpler and more reasonable picture of the atomic spin, therefore qualifies as a more appropriate definition of the electromagnetic angular momentum. Our observation gives important hint on the delicate issue of gluon contribution to the nucleon spin.展开更多
Nanocrystalline and amorphous Mg2Ni-type（Mg24Ni10Cu2）100–xNdx（x = 0, 5, 10, 15, 20） alloys were prepared by melt-spinning technology. The structures of as-cast and spun alloys were characterised by X-ray diffract...Nanocrystalline and amorphous Mg2Ni-type（Mg24Ni10Cu2）100–xNdx（x = 0, 5, 10, 15, 20） alloys were prepared by melt-spinning technology. The structures of as-cast and spun alloys were characterised by X-ray diffraction,scanning electron microscopy and transmission electron microscopy. Electrochemical performance of the alloy electrodes was measured using an automatic galvanostatic system. The electrochemical impedance spectra and Tafel polarisation curves of the alloy electrodes were plotted using an electrochemical work station. The hydrogen diffusion coefficients were calculated using the potential step method. Results indicate that all the as-cast alloys present a multiphase structure with Mg2 Ni type as the major phase with Mg6 Ni, Nd5Mg41 and Nd Ni as secondary phases. The secondary phases increased with the increasing Nd content. The as-spun Nd-free alloy exhibited nanocrystalline structure, whereas the as-spun Nd-doped alloys exhibited nanocrystalline and amorphous structures. These results suggest that adding Nd facilitates glass formation of Mg2Ni-type alloys. Melt spinning and Nd addition improved alloy electrochemical performance, which includes discharge potential characteristics, discharge capacity, electrochemical cycle stability and high-rate discharge ability.展开更多
La 0.5- x Y x Ba 0.5 CoO 3 polycrystals were prepared by solid state reaction. The substituting effects of Y for La on the magnetic and transport properties of the materials were studied systematically...La 0.5- x Y x Ba 0.5 CoO 3 polycrystals were prepared by solid state reaction. The substituting effects of Y for La on the magnetic and transport properties of the materials were studied systematically. The results indicate that substitution of Y induces two effects. Firstly, the charge transfer from Y to 3d orbital of Co happens. This causes the molecular magnetic moment to decrease. Secondly, the antiferromagnetic exchange interaction of Co ions appears. When the content of Y is less than or equal to 30%, the non colinear structure of spins in materials is observed. When the content of Y is greater than 30%, the materials transit from predominant ferromagnetic state to predominant antiferromagnetic one. The conductive mechanism for the materials with different content of Y belongs to the variable range hopping conduction of polarons. The resistivity of materials increases sharply with increasing Y content.展开更多
We report a study of the structure and magnetic properties of the S=3/2 zigzag spin chain compound BaCoTe_(2)O_(7).Neutron diffraction measurements show that it crystallizes in the noncentrosymmetric space group Ama2 ...We report a study of the structure and magnetic properties of the S=3/2 zigzag spin chain compound BaCoTe_(2)O_(7).Neutron diffraction measurements show that it crystallizes in the noncentrosymmetric space group Ama2 with a canted↑↑↓↓spin structure along the quasi-one-dimensional zigzag chain and a moment size of 1.89(2)μBat 2 K.Both magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at TN=6.2 K.A negative Curie-Weiss temperature,ΘCW=-74.7(2) K,and an empirical frustration parameter,f=|ΘCW|/TN≈12,are obtained by fitting the magnetic susceptibility,indicating antiferromagnetic interactions and strong magnetic frustration.From ultraviolet-visible absorption spectroscopy and first-principles calculations,an indirect band gap of 2.68(2) eV is determined.We propose that the canted zigzag spin chain of BaCoTe_(2)O_(7) may produce a change in the polarization via the exchange-striction mechanism.展开更多
Both the PHENIX and STAR experiments at the Relativistic Heavy Ion Collider （RHIC） at Brookhaven National Laboratory are running polarized proton-proton collisions at √s = 200 and 500 GeV. The main goal of the RHIC...Both the PHENIX and STAR experiments at the Relativistic Heavy Ion Collider （RHIC） at Brookhaven National Laboratory are running polarized proton-proton collisions at √s = 200 and 500 GeV. The main goal of the RHIC spin physics program is to gain deeper insight into the spin structure of the nucleon. We will give an overview of recent spin results from RHIC, particularly the study of gluon polarization via jet/hadron production and sea quark polarization via W boson production in longitudinally polarized proton-proton collisions.展开更多
Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As...Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As） were investigated by using local spin density approximation （LSDA）. Amongst the systems under investigation, CoECrGe and Co2CrGa give I00% spin polarization at the Fermi level （EF）. Co2CrGe and CoECrGa are the most stable half-metallic ferromagnets （HMFs）; their EF lie exactly at the gap of 0.24 eV and 0.38 eV, respectively, in the spin-down channel. Even though CoaCrAs gives a distinct and bigger gap as compared to CoECrGa and CoECrGe, its EF is not located at the middle of the gap in the spin-down channel. We have also found that the total magnetic moments increase as the Z goes from Ga to As. The calculated density of states and band structures show the HMF character for CoECrGe and Co2CrGa.展开更多
Four new heterotrinuclear complexes have been synthesized and characterized, namely {[Ni(L)2]2[Cu(opba)]}(ClO4)2, where opba denotes o-phenylenebis(oxamato) and L stands for 1,10-phenanthroline(phen) (1), 5-nitro-1,10...Four new heterotrinuclear complexes have been synthesized and characterized, namely {[Ni(L)2]2[Cu(opba)]}(ClO4)2, where opba denotes o-phenylenebis(oxamato) and L stands for 1,10-phenanthroline(phen) (1), 5-nitro-1,10-phenanthroline(NO2-phen) (2), 2,2'-bipyridyl(bpy) (3) and 4,4'-dimethyl-2,2'-bipyridyl(Me2bpy) (4). The temperature dependence of the magnetic susceptibility of {[Ni(phen)2]2[Cu(opba)]}(ClO4)2.3H2O has been studied in the 4-300 K range, giving the exchange integral J=-109 cm-1. The MT vs. T plot exhibits a minimum at about 100 K, characteristic of this kind of coupled polymetallic complex with an irregular spin-state structure.展开更多
CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ elec...CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ electrolysis in the sample tube in the ESR cavity at 298 and 110K with the spectral data展开更多
A toric origami manifold,introduced by Cannas da Silva,Guillemin and Pires,is a generalization of a toric symplectic manifold.For a toric symplectic manifold,its equivariant Chern classes can be described in terms of ...A toric origami manifold,introduced by Cannas da Silva,Guillemin and Pires,is a generalization of a toric symplectic manifold.For a toric symplectic manifold,its equivariant Chern classes can be described in terms of the corresponding Delzant polytope and the stabilization of its tangent bundle splits as a direct sum of complex line bundles.But in general a toric origami manifold is not simply connected,so the algebraic topology of a toric origami manifold is more difficult than a toric symplectic manifold.In this paper they give an explicit formula of the equivariant Chern classes of an oriented toric origami manifold in terms of the corresponding origami template.Furthermore,they prove the stabilization of the tangent bundle of an oriented toric origami manifold also splits as a direct sum of complex line bundles.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2014CB920902)the National Natural Science Foundation of China(Grant Nos.61306105 and 51572278)+1 种基金the Information Science and Technology(TNList)Cross-discipline Foundation from Tsinghua National Laboratory,Chinathe Fund from the State Key Laboratory of Electronic Thin Films and Integrated Devices,University of Electronic Science and Technology of China,Chengdu 610054,China
文摘Due to the upcoming demands of next-generation electronic/magnetoelectronic devices with low-energy consumption,emerging correlated materials（such as superconductors,topological insulators and manganites） are one of the highly promising candidates for the applications.For the past decades,manganites have attracted great interest due to the colossal magnetoresistance effect,charge-spin-orbital ordering,and electronic phase separation.However,the incapable of deterministic control of those emerging low-dimensional spin structures at ambient condition restrict their possible applications.Therefore,the understanding and control of the dynamic behaviors of spin order parameters at nanoscale in manganites under external stimuli with low energy consumption,especially at room temperature is highly desired.In this review,we collected recent major progresses of nanoscale control of spin structures in manganites at low dimension,especially focusing on the control of their phase boundaries,domain walls as well as the topological spin structures（e.g.,skyrmions）.In addition,capacitor-based prototype spintronic devices are proposed by taking advantage of the above control methods in manganites.This capacitor-based structure may provide a new platform for the design of future spintronic devices with low-energy consumption.
文摘We discuss the nucleon spin structure function g<SUB>1</SUB> and the difference between the proton and neutron targets , based on quark model calculation. Quark-hadron duality for the nucleon spin structure function is also analyzed. Effects of the Δ(1232) and Roper P<SUB>11</SUB>(1440) resonances on the spin structure function and on the difference are mentioned. The results of different models for the Roper resonance are also addressed.
文摘By employing the parametrization form of the nucleon spin structure functionin the resonance region, which includes the contributions of the resonance peaks and of nonresonancebackground, we study Bloom—Oilman quark-hadron duality of g_1 both in the inelastic resonanceregion and elastic one.
文摘Abstract We examine the contribution of electromagnetic field to the atomic spin, by adopting two different, both gauge invariant definitions of the electromagnetic angular momentum：→JI≡fd3x∈0→r×（→E×→B）and→JII≡fd3x（∈0→E×→A⊥＋∈0Ei→τ× A⊥i）.Notably, at the classical level, →JI gives an exactly null result while →JI gives a finite value. This suggests that Jn leads to a simpler and more reasonable picture of the atomic spin, therefore qualifies as a more appropriate definition of the electromagnetic angular momentum. Our observation gives important hint on the delicate issue of gluon contribution to the nucleon spin.
基金financially supported by the National Natural Science Foundation of China (Nos. 51161015 and 51371094)Natural Science Foundation of Inner Mongolia, China (No. 2011ZD10)
文摘Nanocrystalline and amorphous Mg2Ni-type（Mg24Ni10Cu2）100–xNdx（x = 0, 5, 10, 15, 20） alloys were prepared by melt-spinning technology. The structures of as-cast and spun alloys were characterised by X-ray diffraction,scanning electron microscopy and transmission electron microscopy. Electrochemical performance of the alloy electrodes was measured using an automatic galvanostatic system. The electrochemical impedance spectra and Tafel polarisation curves of the alloy electrodes were plotted using an electrochemical work station. The hydrogen diffusion coefficients were calculated using the potential step method. Results indicate that all the as-cast alloys present a multiphase structure with Mg2 Ni type as the major phase with Mg6 Ni, Nd5Mg41 and Nd Ni as secondary phases. The secondary phases increased with the increasing Nd content. The as-spun Nd-free alloy exhibited nanocrystalline structure, whereas the as-spun Nd-doped alloys exhibited nanocrystalline and amorphous structures. These results suggest that adding Nd facilitates glass formation of Mg2Ni-type alloys. Melt spinning and Nd addition improved alloy electrochemical performance, which includes discharge potential characteristics, discharge capacity, electrochemical cycle stability and high-rate discharge ability.
文摘La 0.5- x Y x Ba 0.5 CoO 3 polycrystals were prepared by solid state reaction. The substituting effects of Y for La on the magnetic and transport properties of the materials were studied systematically. The results indicate that substitution of Y induces two effects. Firstly, the charge transfer from Y to 3d orbital of Co happens. This causes the molecular magnetic moment to decrease. Secondly, the antiferromagnetic exchange interaction of Co ions appears. When the content of Y is less than or equal to 30%, the non colinear structure of spins in materials is observed. When the content of Y is greater than 30%, the materials transit from predominant ferromagnetic state to predominant antiferromagnetic one. The conductive mechanism for the materials with different content of Y belongs to the variable range hopping conduction of polarons. The resistivity of materials increases sharply with increasing Y content.
基金supported by the National Natural Science Foundation of China(Grant No.11904414)the National Key Research and Development Program of China(Grant No.2019YFA0705702)+3 种基金supported by the National Key Research and Development Program of China(Grant Nos.2018YFA0306001,and 2017YFA0206203)the National Natural Science Foundation of China(Grant No.11974432)the Guangdong Basic and Applied Basic Research Fund(Grant No.2019A1515011337)the Leading Talent Program of Guangdong Special Projects。
文摘We report a study of the structure and magnetic properties of the S=3/2 zigzag spin chain compound BaCoTe_(2)O_(7).Neutron diffraction measurements show that it crystallizes in the noncentrosymmetric space group Ama2 with a canted↑↑↓↓spin structure along the quasi-one-dimensional zigzag chain and a moment size of 1.89(2)μBat 2 K.Both magnetic susceptibility and specific heat measurements yield an antiferromagnetic phase transition at TN=6.2 K.A negative Curie-Weiss temperature,ΘCW=-74.7(2) K,and an empirical frustration parameter,f=|ΘCW|/TN≈12,are obtained by fitting the magnetic susceptibility,indicating antiferromagnetic interactions and strong magnetic frustration.From ultraviolet-visible absorption spectroscopy and first-principles calculations,an indirect band gap of 2.68(2) eV is determined.We propose that the canted zigzag spin chain of BaCoTe_(2)O_(7) may produce a change in the polarization via the exchange-striction mechanism.
基金Acknowledgements The work was supported by the National Natural Science Foundation of China, China, under Grant Nos. 11175106 and 11222551, and the Natural Science Foundation of Shandong Province, China, under Grant No. ZR2013JQ001.
文摘Both the PHENIX and STAR experiments at the Relativistic Heavy Ion Collider （RHIC） at Brookhaven National Laboratory are running polarized proton-proton collisions at √s = 200 and 500 GeV. The main goal of the RHIC spin physics program is to gain deeper insight into the spin structure of the nucleon. We will give an overview of recent spin results from RHIC, particularly the study of gluon polarization via jet/hadron production and sea quark polarization via W boson production in longitudinally polarized proton-proton collisions.
基金the DST Inspier research fellowship and RKT, a research grant from UGC(New Delhi,India)
文摘Volume optimization was performed to obtain the theoretical lattice constants by using the generalized gradient approximation （GGA）. The electronic and magnetic properties of Heusler alloys CoaCrZ （Z -- Ga, Ge, As） were investigated by using local spin density approximation （LSDA）. Amongst the systems under investigation, CoECrGe and Co2CrGa give I00% spin polarization at the Fermi level （EF）. Co2CrGe and CoECrGa are the most stable half-metallic ferromagnets （HMFs）; their EF lie exactly at the gap of 0.24 eV and 0.38 eV, respectively, in the spin-down channel. Even though CoaCrAs gives a distinct and bigger gap as compared to CoECrGa and CoECrGe, its EF is not located at the middle of the gap in the spin-down channel. We have also found that the total magnetic moments increase as the Z goes from Ga to As. The calculated density of states and band structures show the HMF character for CoECrGe and Co2CrGa.
基金Project supported by the National Natural Science Foundation of China and 21st Century Youth Foundation of Tianjin,China.
文摘Four new heterotrinuclear complexes have been synthesized and characterized, namely {[Ni(L)2]2[Cu(opba)]}(ClO4)2, where opba denotes o-phenylenebis(oxamato) and L stands for 1,10-phenanthroline(phen) (1), 5-nitro-1,10-phenanthroline(NO2-phen) (2), 2,2'-bipyridyl(bpy) (3) and 4,4'-dimethyl-2,2'-bipyridyl(Me2bpy) (4). The temperature dependence of the magnetic susceptibility of {[Ni(phen)2]2[Cu(opba)]}(ClO4)2.3H2O has been studied in the 4-300 K range, giving the exchange integral J=-109 cm-1. The MT vs. T plot exhibits a minimum at about 100 K, characteristic of this kind of coupled polymetallic complex with an irregular spin-state structure.
文摘CH_3CCo_3(CO)_9 was synthesized from the reaction between chloralose and Co_2(CO)_. The radical anion was generated by electrochemical reduction,and electron spin resonance spectra in THF were recorded by in situ electrolysis in the sample tube in the ESR cavity at 298 and 110K with the spectral data
基金supported by the National Natural Science Foundation of China(Nos.11801186,11901218)。
文摘A toric origami manifold,introduced by Cannas da Silva,Guillemin and Pires,is a generalization of a toric symplectic manifold.For a toric symplectic manifold,its equivariant Chern classes can be described in terms of the corresponding Delzant polytope and the stabilization of its tangent bundle splits as a direct sum of complex line bundles.But in general a toric origami manifold is not simply connected,so the algebraic topology of a toric origami manifold is more difficult than a toric symplectic manifold.In this paper they give an explicit formula of the equivariant Chern classes of an oriented toric origami manifold in terms of the corresponding origami template.Furthermore,they prove the stabilization of the tangent bundle of an oriented toric origami manifold also splits as a direct sum of complex line bundles.
