The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the differ...The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the single-ion anisotropy are included, our results indicate that there are compensation points at finite temperatures. When the next-nearest-neighbor interaction exceeds a minimum value that depends on the other parameters in the Hamiltonian, the compensation point disappears. The next-nearest-neighbor interaction has the effect of changing the compensation temperature.展开更多
We study the entanglement in anisotropie （1/2,1） mixed-spin Heisenberg XY model under the presence of an external magnetic field at thermal equilibrium. By adjusting the anisotropic parameter and the magnetic field,...We study the entanglement in anisotropie （1/2,1） mixed-spin Heisenberg XY model under the presence of an external magnetic field at thermal equilibrium. By adjusting the anisotropic parameter and the magnetic field, one is able to obtain entanglement at higher temperature. We find the evidence of the quantum phase transition in the model and observe that the quantum phase transition point at low temperature moves toward weak magnetic field with the increase of the anisotropic parameter.展开更多
Within the t-J model, the charge transport and spin response of the doped bilayer triangular antiferromagnetare studied by considering the bilayer interaction. Although the bilayer interaction leads to the band splitt...Within the t-J model, the charge transport and spin response of the doped bilayer triangular antiferromagnetare studied by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in theelectronic structure, the qualitative behaviors of the physical properties are the same as in the single layer case. Theconductivity spectrum shows the low-energy peak and unusual midinfrared band, the temperature-dependent resistivityis characterized by the nonlinearity metallic-like behavior in the higher temperature range and the deviation from themetallic-like behavior in the lower temperature range and the commensurate neutron scattering peak near the half-fillingis split into six incommensurate peaks in the underdoped regime, with the incommensurability increasing with the holeconcentration at lower dopings, and saturating at higher dopings.展开更多
Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium sp...Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium spin polarization （NESP） in NMS during spin-polarized injection through the magnetic p-n junction. Based on the theory in semiconductor physics, a model is established and the boundary conditions are determined in the case of no external spin-polarized injection and low bias. The control parameters that may influence the NESP in NMS are indicated by calculating the distribution of spin polarization. They are the doping concentrations, the equilibrium spin polarization in MS and the bias. The effective spin-polarized injection can be realized more easily by optimizing the above parameters.展开更多
The authors＇ theoretical investigation on the high-frequency response of magnetized metallic magnetic films showed that magnetic films may become left-handed materials （LHMs） near the ferromagnetic resonance freque...The authors＇ theoretical investigation on the high-frequency response of magnetized metallic magnetic films showed that magnetic films may become left-handed materials （LHMs） near the ferromagnetic resonance frequency of incident waves with right-handed circular polarization （RCP） and linear polarization （LP）. The frequency range where LHM exists depends on the waves polarization, the magnetic damping coefficient, and the ferromagnetic characteristic frequency corn of the film. There also exists a critical damping coefficient ac, above which the left-handed properties disappear completely.展开更多
Ab initio within the full potential linearized augmented plane wave （FP-LAPW） method with the GGA＋U approach is applied to study the electronic structures of two compounds NaK3（NpO2）4（SO4）4（H2O）2 and NaNpO2SO...Ab initio within the full potential linearized augmented plane wave （FP-LAPW） method with the GGA＋U approach is applied to study the electronic structures of two compounds NaK3（NpO2）4（SO4）4（H2O）2 and NaNpO2SO4H2O. The present calculations show that the major part of the spin magnetic moment in these two compounds is from Np（V） ions, and the origin of the cation-cation interactions between Np comes from the spin polarization effect within Np-ONv-Np bonds.展开更多
The aim of this paper is to present a rigorous mathematical proof of the dynamical laws for the topological solitons( magnetic vortices) in ferromagnets and anti-ferromagnets. It is achieved through the conservation l...The aim of this paper is to present a rigorous mathematical proof of the dynamical laws for the topological solitons( magnetic vortices) in ferromagnets and anti-ferromagnets. It is achieved through the conservation laws for the topological vorticity and the weak convergence methods.展开更多
The equations of state of spin-polarized nuclear matter and pure neutron matter are studied in the framework of the Brueckner–Hartree–Fock theory including a three-body force. The energy per nucleon E<SUB>A<...The equations of state of spin-polarized nuclear matter and pure neutron matter are studied in the framework of the Brueckner–Hartree–Fock theory including a three-body force. The energy per nucleon E<SUB>A</SUB>(δ) calculated in the full range of spin polarization for symmetric nuclear matter and pure neutron matter fulfills a parabolic law. In both the cases the spin-symmetry energy is calculated as a function of the baryonic density along with the related quantities such as the magnetic susceptibility and the Landau parameter G<SUB>0</SUB>. The main effect of the three-body force is to strongly reduce the degenerate Fermi gas magnetic susceptibility even more than the value with only two-body force. The equation of state is monotonically increasing with the density for all spin-aligned configurations studied here so that no any signature is found for a spontaneous transition to a ferromagnetic state.展开更多
In this paper, we apply the two-time Green's function method, and provide a simple way to study themagnetic properties of one-dimensional spin-(S, s) Heisenberg ferromagnets.The magnetic susceptibility and correla...In this paper, we apply the two-time Green's function method, and provide a simple way to study themagnetic properties of one-dimensional spin-(S, s) Heisenberg ferromagnets.The magnetic susceptibility and correlationfunctions are obtained by using the Tyablikov decoupling approximation.Our results show that the magnetic susceptibilityand correlation length are a monotonically decreasing function of temperature regardless of the mixed spins.It isfound that in the case of S = s, our results of one-dimensional mixed-spin model is reduced to be those of the isotropicferromagnetic Heisenberg chain in the whole temperature region.Our results for the susceptibility are in agreement withthose obtained by other theoretical approaches.展开更多
We extend a previous result of ours [G.S. Tian, Phys. Rev. B63 (2001) 224413] on the antiferromagnetic spin correlations in the half-filled Hubbard model at finite temperature to the double-exchange model. To overcome...We extend a previous result of ours [G.S. Tian, Phys. Rev. B63 (2001) 224413] on the antiferromagnetic spin correlations in the half-filled Hubbard model at finite temperature to the double-exchange model. To overcome the mathematical difficulty caused by the localized spin freedom in this model, we apply both Zener's argument and the finite-temperature spin-reflection-positivity method to show rigorously that, at any temperature , the spin correlations in the half-filled double-exchange model are predominantly antiferromagnetic. This conclusion is completely consistent with the experimental observations and the previous theoretical results by approximate methods.展开更多
The article presents the results of experimental studies of the physical mechanisms and magnetic switching dynamics of films with one or two magnetic nanolayers under an irradiation picosecond and femtosecond laser pu...The article presents the results of experimental studies of the physical mechanisms and magnetic switching dynamics of films with one or two magnetic nanolayers under an irradiation picosecond and femtosecond laser pulses and also the samples of data recording devices on the spin storage medium are described. The study used a film with perpendicular anisotropy （Tb22Co5Fe73/Pr6O11/Tb29Co5Fe76, Tb25Co5Fe70/Al2O3, Tb22Co5Fe73, Tb19Co5Fe76） and films planar single-axis magnetic anisotropy （Co80Fe20/Pr6O11/CO30Fe70）. The magnetic switching of magnetic layers under action the magnetic field of a spin current is the most important for practical use in elements of spintronic. The spin current can also be realized using short electrical pulses. On the basis of this mechanism, the high-speed recording of information on the spin carrier has been realized.展开更多
In the present paper we propose a spin-1/2 chain which provides an exactly solvable example to studythe Ising criticality with the central charge c = 1/2. We performthe diagonalization of this model in the presence of...In the present paper we propose a spin-1/2 chain which provides an exactly solvable example to studythe Ising criticality with the central charge c = 1/2. We performthe diagonalization of this model in the presence ofmagnetic field. From the full energy spectrum, the central charge and the scaling dimensions are given at the criticalpoint. The results show evidently that the quantum Ising criticality exists in such a system.展开更多
A two-fold Cayley tree with fully q-coordinated sites is constructed and the spin-1 Blume-Capel model in the presence of an external magnetic field is solved exactly. The relevant properties such as magnetization m an...A two-fold Cayley tree with fully q-coordinated sites is constructed and the spin-1 Blume-Capel model in the presence of an external magnetic field is solved exactly. The relevant properties such as magnetization m and square magnetic moment q are investigated as functions of temperature and external magnetic fieId both for ferromagnetic and antiferromagnetic couplings. In the study, we propose a possible mechanism of the plateau based on the exchange couplings.展开更多
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10574048 and 20490210
文摘The multisublattice Green＇s function technique is applied to study the magnetic properties of a mixed spin-2 and spin-5/2 Heisenberg ferrimagnetic system on a two-dimensional honeycomb lattice. The role of the different interactions in the Hamiltonian is explored. When only the nearest-neighbor interaction and the single-ion anisotropy are included, our results indicate that there are compensation points at finite temperatures. When the next-nearest-neighbor interaction exceeds a minimum value that depends on the other parameters in the Hamiltonian, the compensation point disappears. The next-nearest-neighbor interaction has the effect of changing the compensation temperature.
基金supported by National Natural Science Foundation of China under Grant No.10674181
文摘We study the entanglement in anisotropie （1/2,1） mixed-spin Heisenberg XY model under the presence of an external magnetic field at thermal equilibrium. By adjusting the anisotropic parameter and the magnetic field, one is able to obtain entanglement at higher temperature. We find the evidence of the quantum phase transition in the model and observe that the quantum phase transition point at low temperature moves toward weak magnetic field with the increase of the anisotropic parameter.
文摘Within the t-J model, the charge transport and spin response of the doped bilayer triangular antiferromagnetare studied by considering the bilayer interaction. Although the bilayer interaction leads to the band splitting in theelectronic structure, the qualitative behaviors of the physical properties are the same as in the single layer case. Theconductivity spectrum shows the low-energy peak and unusual midinfrared band, the temperature-dependent resistivityis characterized by the nonlinearity metallic-like behavior in the higher temperature range and the deviation from themetallic-like behavior in the lower temperature range and the commensurate neutron scattering peak near the half-fillingis split into six incommensurate peaks in the underdoped regime, with the incommensurability increasing with the holeconcentration at lower dopings, and saturating at higher dopings.
基金Project supported by the National Natural Science Foundation of China （Grant No 60606021）, the Specialized Research Fund for the Doctoral Program of Higher Education of China （Grant No 20060003067） and the Key Fundamental Research Foundation of Tsinghua University of China （Grant No Jz2001010）.
文摘Effective spin-polarized injection from magnetic semiconductor （MS） to nonmagnetic semiconductor （NMS） has been highlighted in recent years. In this paper we study theoretically the dependence of nonequilibrium spin polarization （NESP） in NMS during spin-polarized injection through the magnetic p-n junction. Based on the theory in semiconductor physics, a model is established and the boundary conditions are determined in the case of no external spin-polarized injection and low bias. The control parameters that may influence the NESP in NMS are indicated by calculating the distribution of spin polarization. They are the doping concentrations, the equilibrium spin polarization in MS and the bias. The effective spin-polarized injection can be realized more easily by optimizing the above parameters.
基金Project supported by the National Basic Research Program (973) ofChina (No. 2004CB719805) and the National Natural Science Foun-dation of China (No. 60471020)
文摘The authors＇ theoretical investigation on the high-frequency response of magnetized metallic magnetic films showed that magnetic films may become left-handed materials （LHMs） near the ferromagnetic resonance frequency of incident waves with right-handed circular polarization （RCP） and linear polarization （LP）. The frequency range where LHM exists depends on the waves polarization, the magnetic damping coefficient, and the ferromagnetic characteristic frequency corn of the film. There also exists a critical damping coefficient ac, above which the left-handed properties disappear completely.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10574048 and 20490210
文摘Ab initio within the full potential linearized augmented plane wave （FP-LAPW） method with the GGA＋U approach is applied to study the electronic structures of two compounds NaK3（NpO2）4（SO4）4（H2O）2 and NaNpO2SO4H2O. The present calculations show that the major part of the spin magnetic moment in these two compounds is from Np（V） ions, and the origin of the cation-cation interactions between Np comes from the spin polarization effect within Np-ONv-Np bonds.
文摘The aim of this paper is to present a rigorous mathematical proof of the dynamical laws for the topological solitons( magnetic vortices) in ferromagnets and anti-ferromagnets. It is achieved through the conservation laws for the topological vorticity and the weak convergence methods.
基金中国科学院知识创新工程项目，国家重点基础研究发展计划(973计划)，the Important Pre-research Project，科技部资助项目
文摘The equations of state of spin-polarized nuclear matter and pure neutron matter are studied in the framework of the Brueckner–Hartree–Fock theory including a three-body force. The energy per nucleon E<SUB>A</SUB>(δ) calculated in the full range of spin polarization for symmetric nuclear matter and pure neutron matter fulfills a parabolic law. In both the cases the spin-symmetry energy is calculated as a function of the baryonic density along with the related quantities such as the magnetic susceptibility and the Landau parameter G<SUB>0</SUB>. The main effect of the three-body force is to strongly reduce the degenerate Fermi gas magnetic susceptibility even more than the value with only two-body force. The equation of state is monotonically increasing with the density for all spin-aligned configurations studied here so that no any signature is found for a spontaneous transition to a ferromagnetic state.
基金Supported by the Natural Science Foundation of Guangdong Province under Grant No.8151009001000055
文摘In this paper, we apply the two-time Green's function method, and provide a simple way to study themagnetic properties of one-dimensional spin-(S, s) Heisenberg ferromagnets.The magnetic susceptibility and correlationfunctions are obtained by using the Tyablikov decoupling approximation.Our results show that the magnetic susceptibilityand correlation length are a monotonically decreasing function of temperature regardless of the mixed spins.It isfound that in the case of S = s, our results of one-dimensional mixed-spin model is reduced to be those of the isotropicferromagnetic Heisenberg chain in the whole temperature region.Our results for the susceptibility are in agreement withthose obtained by other theoretical approaches.
文摘We extend a previous result of ours [G.S. Tian, Phys. Rev. B63 (2001) 224413] on the antiferromagnetic spin correlations in the half-filled Hubbard model at finite temperature to the double-exchange model. To overcome the mathematical difficulty caused by the localized spin freedom in this model, we apply both Zener's argument and the finite-temperature spin-reflection-positivity method to show rigorously that, at any temperature , the spin correlations in the half-filled double-exchange model are predominantly antiferromagnetic. This conclusion is completely consistent with the experimental observations and the previous theoretical results by approximate methods.
文摘The article presents the results of experimental studies of the physical mechanisms and magnetic switching dynamics of films with one or two magnetic nanolayers under an irradiation picosecond and femtosecond laser pulses and also the samples of data recording devices on the spin storage medium are described. The study used a film with perpendicular anisotropy （Tb22Co5Fe73/Pr6O11/Tb29Co5Fe76, Tb25Co5Fe70/Al2O3, Tb22Co5Fe73, Tb19Co5Fe76） and films planar single-axis magnetic anisotropy （Co80Fe20/Pr6O11/CO30Fe70）. The magnetic switching of magnetic layers under action the magnetic field of a spin current is the most important for practical use in elements of spintronic. The spin current can also be realized using short electrical pulses. On the basis of this mechanism, the high-speed recording of information on the spin carrier has been realized.
文摘In the present paper we propose a spin-1/2 chain which provides an exactly solvable example to studythe Ising criticality with the central charge c = 1/2. We performthe diagonalization of this model in the presence ofmagnetic field. From the full energy spectrum, the central charge and the scaling dimensions are given at the criticalpoint. The results show evidently that the quantum Ising criticality exists in such a system.
文摘A two-fold Cayley tree with fully q-coordinated sites is constructed and the spin-1 Blume-Capel model in the presence of an external magnetic field is solved exactly. The relevant properties such as magnetization m and square magnetic moment q are investigated as functions of temperature and external magnetic fieId both for ferromagnetic and antiferromagnetic couplings. In the study, we propose a possible mechanism of the plateau based on the exchange couplings.
