利用Heisenberg交换作用模型,格林函数法研究X Y Z模型亚铁磁性Heisenberg系统下的二维正方复式晶格的自旋波解.通过求解算符的关联函数和热力学系综平均值得到了系统基态的饱和磁化强度MT/M0,并分析了系统基态的饱和磁化强度MT(A,B)/M0...利用Heisenberg交换作用模型,格林函数法研究X Y Z模型亚铁磁性Heisenberg系统下的二维正方复式晶格的自旋波解.通过求解算符的关联函数和热力学系综平均值得到了系统基态的饱和磁化强度MT/M0,并分析了系统基态的饱和磁化强度MT(A,B)/M0(A,B)随自旋量子数,各向异性参数X1,X2,X3的变化规律,得到下列结果:随X1增加,MTA/M0A和MTB/M0B的绝对值减小.随参数X3的增加,A次晶格的基态磁化强度急剧下降的X1位置向后移,B次晶格的基态磁化强度绝对值急剧下降的X1位置也向后移,且B次晶格与A次晶格的基态磁化强度方向相反.展开更多
采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子...采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子气密度、空间感应电势和感应电场对入射粒子的阻止力的一般表达式。结果表明,自旋效应对电子气密度分布和阻止力随速度变化均有一定的影响。在入射粒子附近,磁场使自旋向上的电子气密度振荡加强,而对自旋向下的电子气密度振荡起到抑制作用。由于两个电子气平面的相互耦合作用,阻止力随速度变化曲线出现了明显的双峰结构,随着入射磁场振幅和波数的增大,在速度较高的区域,无论电子自旋向上或向下,曲线均出现了明显的振荡衰减情况。展开更多
The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that three modulated energy gaps exist in the magnon ene...The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that three modulated energy gaps exist in the magnon energy band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the three energy gaps. The magnon energy gaps of the four-layer ferromagnetic superlattice are different from those of the three-layer one. For the four-layer ferromagnetic superlattice, the disappearance of the magnon energy gaps △ω12, △ω23 and △ω34 all correlates with the symmetry of this system. The zero energy gap △ω23 correlates with the symmetry of interlayer exchange couplings, while the vanishing of the magnon energy gaps △ω12 and △ω34 corresponds to a translational symmetry of x-direction in the lattice. When the parameters of the system deviate from these symmetries, the three energy gaps will increase.展开更多
The Einstein-Podolsky-Rosen paradox is resolved dynamically by using spin-dependent quantum trajectories inferred from Dirac’s equation for a relativistic electron. The theory provides a practical computational metho...The Einstein-Podolsky-Rosen paradox is resolved dynamically by using spin-dependent quantum trajectories inferred from Dirac’s equation for a relativistic electron. The theory provides a practical computational methodology for studying entanglement versus disentanglement for realistic Hamiltonians.展开更多
It has been widely accepted that silicene is a topological insulator, and its gap closes first and then opens again with increasing electric field, which indicates a topological phase transition from the quantum spin ...It has been widely accepted that silicene is a topological insulator, and its gap closes first and then opens again with increasing electric field, which indicates a topological phase transition from the quantum spin Hall state to the band insulator state. However, due to the relatively large atomic spacing of silicene, which reduces the bandwidth, the electron–electron interaction in this system is considerably strong and cannot be ignored. The Hubbard interaction, intrinsic spin orbital coupling(SOC), and electric field are taken into consideration in our tight-binding model, with which the phase diagram of silicene is carefully investigated on the mean field level. We have found that when the magnitudes of the two mass terms produced by the Hubbard interaction and electric potential are close to each other, the intrinsic SOC flips the sign of the mass term at either K or K for one spin and leads to the emergence of the spin-polarized quantum anomalous Hall state.展开更多
文摘利用Heisenberg交换作用模型,格林函数法研究X Y Z模型亚铁磁性Heisenberg系统下的二维正方复式晶格的自旋波解.通过求解算符的关联函数和热力学系综平均值得到了系统基态的饱和磁化强度MT/M0,并分析了系统基态的饱和磁化强度MT(A,B)/M0(A,B)随自旋量子数,各向异性参数X1,X2,X3的变化规律,得到下列结果:随X1增加,MTA/M0A和MTB/M0B的绝对值减小.随参数X3的增加,A次晶格的基态磁化强度急剧下降的X1位置向后移,B次晶格的基态磁化强度绝对值急剧下降的X1位置也向后移,且B次晶格与A次晶格的基态磁化强度方向相反.
文摘采用线性化自旋量子流体动力学模型(Spin quantum hydrodynamic model SQHD)与Poisson方程相结合,研究了在外加磁场的作用下,电子自旋效应对带电粒子与双层二维电子气平面相互作用的影响。在适当的边界条件下,推导出两个平面内感应电子气密度、空间感应电势和感应电场对入射粒子的阻止力的一般表达式。结果表明,自旋效应对电子气密度分布和阻止力随速度变化均有一定的影响。在入射粒子附近,磁场使自旋向上的电子气密度振荡加强,而对自旋向下的电子气密度振荡起到抑制作用。由于两个电子气平面的相互耦合作用,阻止力随速度变化曲线出现了明显的双峰结构,随着入射磁场振幅和波数的增大,在速度较高的区域,无论电子自旋向上或向下,曲线均出现了明显的振荡衰减情况。
基金Project supported by the National Natural Science Foundation of China (Grant Nos 50331030, 10674139 and 10274087)the Natural Science Foundation of Liaoning Province, China (Grant No 20062040)
文摘The magnon energy band in a four-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that three modulated energy gaps exist in the magnon energy band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the three energy gaps. The magnon energy gaps of the four-layer ferromagnetic superlattice are different from those of the three-layer one. For the four-layer ferromagnetic superlattice, the disappearance of the magnon energy gaps △ω12, △ω23 and △ω34 all correlates with the symmetry of this system. The zero energy gap △ω23 correlates with the symmetry of interlayer exchange couplings, while the vanishing of the magnon energy gaps △ω12 and △ω34 corresponds to a translational symmetry of x-direction in the lattice. When the parameters of the system deviate from these symmetries, the three energy gaps will increase.
文摘The Einstein-Podolsky-Rosen paradox is resolved dynamically by using spin-dependent quantum trajectories inferred from Dirac’s equation for a relativistic electron. The theory provides a practical computational methodology for studying entanglement versus disentanglement for realistic Hamiltonians.
基金supported by the National Key Basic Research Program of China(Grant Nos.2014CB920903,2013CB921903,2011CBA00108,and 2012CB937500)the National Natural Science Foundation of China(Grant Nos.11021262,11172303,11404022,11225418,and 11174337)+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20121101110046)the Excellent Young Scholars Research Fund of Beijing Institute of Technology(Grant No.2014CX04028)the Basic Research Funds of Beijing Institute of Technology(Grant No.20141842001)
文摘It has been widely accepted that silicene is a topological insulator, and its gap closes first and then opens again with increasing electric field, which indicates a topological phase transition from the quantum spin Hall state to the band insulator state. However, due to the relatively large atomic spacing of silicene, which reduces the bandwidth, the electron–electron interaction in this system is considerably strong and cannot be ignored. The Hubbard interaction, intrinsic spin orbital coupling(SOC), and electric field are taken into consideration in our tight-binding model, with which the phase diagram of silicene is carefully investigated on the mean field level. We have found that when the magnitudes of the two mass terms produced by the Hubbard interaction and electric potential are close to each other, the intrinsic SOC flips the sign of the mass term at either K or K for one spin and leads to the emergence of the spin-polarized quantum anomalous Hall state.
