A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small ...A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small thickness,an easy-plane anisotropy in the Fe Ge layer is taken into account,and the skyrmion-crystal state is favored to appear for low anisotropies and intermediate Fe Ge/Ni interlayer exchange couplings,and finally transformed from a labyrinth-like and into an out-ofplane uniform state for the large couplings or into an in-plane state for the high anisotropies.Furthermore,the maximum skyrmion charge number is bigger for the periodic and fixed boundary conditions with an out-of-plane magnetization;on the contrary,the Bloch-type skyrmions can be frozen and stabilized for the larger couplings on the fixed boundary with an in-plane magnetization,similar to the experimental results of the magnetic-field-induced skyrmions.Finally,the skyrmion charge number and diameter both decrease if the nonmagnetic defects exist,and the skyrmion centers are prone to being captured by defect sites.This work evidences that the ensembles of homochiral skyrmions stabilized in the multilayers fabricated by well-established technologies present a roadmap to design new classes of the materials that can host skyrmions.展开更多
The inter-relation between zero-field splitting （ZFS） parameters and local lattice structures of the （CrSe4）6 clusters in ZnSe semiconductors has been established by using the complete diagonalization （of the ene...The inter-relation between zero-field splitting （ZFS） parameters and local lattice structures of the （CrSe4）6 clusters in ZnSe semiconductors has been established by using the complete diagonalization （of the energy matrix） method. On the basis of this, the local lattice distortions, the ZFS parameters D, a, F and the optical spectrum for Cr2＋ ions doped into ZnSe are theoretically investigated, and the contributions of the spin singlets have been taken into account. The calculated ZFS parameters are in good agreement with the experimental values. From our calculations, the tetragonal distortion parameters AR = 0.091A and Aθ = 4.28° of Cr2＋ in ZnSe are acquired, and the results suggest that there exists a tetragonal expansion distortion for the local lattice structure of （CrSe4）6- clusters in ZnSe crystals. The influence of the spin singlets on ZFS parameters is also discussed, indicating that the contributions to ZFS parameters a and F cannot be ignored.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
The axial zero-field splitting (hereinafter ZFS) D and the rhombic ZFS E of d^9(d^1)configuration ion of the transition metal in any symmetric crystal field are
We used density functional calculations to investigate the electronic origins of the magnetic properties of the high-spin ferric enzyme-substrate complex protocatechuate 3,4-dioxygenase(3,4-PCD).The calculated g-tenso...We used density functional calculations to investigate the electronic origins of the magnetic properties of the high-spin ferric enzyme-substrate complex protocatechuate 3,4-dioxygenase(3,4-PCD).The calculated g-tensors show that ligand-to-metal charge transfer transitions are from the protocatechuate(PCA) and Tyr408 orbitals to the Fe d orbitals,which lead to x-and y-polarized transitions.These polarized transitions require a spin-orbit coupling(SOC) matrix element in the z-direction,Lz(z=z'),resulting in a g z value of 2.0158,significantly deviating from 2.0023.A large zero-field splitting parameter value of+1.147cm-1 is due to △S =-1 spin-orbit mixing with the quartet states for the sextet ground state,accounting for around 73% of the SOC contribution.The SOC matrix elements indicate that the high-spin d 5 system Fe(Ⅲ),3,4-PCD-PCA is a weak spin-crossover compound with an SOC of 31.56 cm-1.展开更多
The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coup...The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).展开更多
基金the National Natural Science Foundation of China(Grant No.11774045)the Joint Research Fund Liaoning-Shenyang National Laboratory for Materials Science(Grant No.20180510008)the Fundamental Research Funds for Central Universities,China(Grant No.N182410008-1)。
文摘A numerical study reports that the zero-field skyrmions in Fe Ge thin films are stabilized when a Fe Ge layer is exchange coupled to a single-domain Ni layer,which has been magnetized perpendicularly.Due to the small thickness,an easy-plane anisotropy in the Fe Ge layer is taken into account,and the skyrmion-crystal state is favored to appear for low anisotropies and intermediate Fe Ge/Ni interlayer exchange couplings,and finally transformed from a labyrinth-like and into an out-ofplane uniform state for the large couplings or into an in-plane state for the high anisotropies.Furthermore,the maximum skyrmion charge number is bigger for the periodic and fixed boundary conditions with an out-of-plane magnetization;on the contrary,the Bloch-type skyrmions can be frozen and stabilized for the larger couplings on the fixed boundary with an in-plane magnetization,similar to the experimental results of the magnetic-field-induced skyrmions.Finally,the skyrmion charge number and diameter both decrease if the nonmagnetic defects exist,and the skyrmion centers are prone to being captured by defect sites.This work evidences that the ensembles of homochiral skyrmions stabilized in the multilayers fabricated by well-established technologies present a roadmap to design new classes of the materials that can host skyrmions.
基金supported by the National Natural Science Foundation of China(Grant Nos.11274235 and 11104190)the Doctoral Education Fund of Education Ministry of China(Grant No.20110181120112)
文摘The inter-relation between zero-field splitting （ZFS） parameters and local lattice structures of the （CrSe4）6 clusters in ZnSe semiconductors has been established by using the complete diagonalization （of the energy matrix） method. On the basis of this, the local lattice distortions, the ZFS parameters D, a, F and the optical spectrum for Cr2＋ ions doped into ZnSe are theoretically investigated, and the contributions of the spin singlets have been taken into account. The calculated ZFS parameters are in good agreement with the experimental values. From our calculations, the tetragonal distortion parameters AR = 0.091A and Aθ = 4.28° of Cr2＋ in ZnSe are acquired, and the results suggest that there exists a tetragonal expansion distortion for the local lattice structure of （CrSe4）6- clusters in ZnSe crystals. The influence of the spin singlets on ZFS parameters is also discussed, indicating that the contributions to ZFS parameters a and F cannot be ignored.
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Project supported by the National Natural Science Foundation of China.
文摘The axial zero-field splitting (hereinafter ZFS) D and the rhombic ZFS E of d^9(d^1)configuration ion of the transition metal in any symmetric crystal field are
基金supported by the "QingLan" Talent Engineering Fundsthrough Tian Shui Normal Universitythe Key Project of the Chinese Ministry of Education (211189)
文摘We used density functional calculations to investigate the electronic origins of the magnetic properties of the high-spin ferric enzyme-substrate complex protocatechuate 3,4-dioxygenase(3,4-PCD).The calculated g-tensors show that ligand-to-metal charge transfer transitions are from the protocatechuate(PCA) and Tyr408 orbitals to the Fe d orbitals,which lead to x-and y-polarized transitions.These polarized transitions require a spin-orbit coupling(SOC) matrix element in the z-direction,Lz(z=z'),resulting in a g z value of 2.0158,significantly deviating from 2.0023.A large zero-field splitting parameter value of+1.147cm-1 is due to △S =-1 spin-orbit mixing with the quartet states for the sextet ground state,accounting for around 73% of the SOC contribution.The SOC matrix elements indicate that the high-spin d 5 system Fe(Ⅲ),3,4-PCD-PCA is a weak spin-crossover compound with an SOC of 31.56 cm-1.
基金supported by the National Natural Science Foundation of China(21263022)University Research Fund of Gansu Province Financial Department,and"QingLan"Talent Engineering Funds of Tianshui Normal University
文摘The two-state reaction mechanism of CpCo(C_4H_4)with isocyanate on the triplet and singlet potential energy surfaces has been investigated at the B3LYP level.A study is described for the computation of spin-orbit coupling of triplet state of the minimal energy crossing point(CP)with their singlet states and of the zerofield splitting(ZFS)parameters of the triplet states,including the full one-and two-electron terms of the BreitPauli Hamiltonian.There are two key crossing points along this two-state reaction pathway.The first crossing point—CP2 exists near^1B.The reacting system will change its spin multiplicity from the triplet state to the singlet state near this crossing region.Although the spin-orbit coupling interaction and ZFS D-tensor of the CP2 region are very strong,the reaction system will occur the reverse intersystem crossing from T_1 to S_0.Therefore,its spin-flip efficiency may be lower.The second crossing point,CP3will again change its spin multiplicity from the singlet state to the triplet state in the Co-Cr bond activation pathway,leading to a decrease in the barrier height of^1TS(CF)from19.5 to 9.5 kcal/mol(1cal=4.182 J),and the efficiency of intersystem crossing from S_0 to T_1 is high because the larger spin-orbit coupling(SOC)matrix elements will result in the overpopulations of the three sublevels of T_1(3.30×10^(-1),3.32×10^(-1),and 3.38×10^(-1),respectively).
