The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that four energy gaps and corresp...The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that four energy gaps and corresponding four frequencie in middle of energy gaps exist in the magnon band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the four frequencies in middle of the energy gaps. When all interlayer exchange couplings are same, the effect of spin quantum numbers on the frequency wg1 in middle of the energy gap Δw12 is complicated, and the frequency wg1 depends on the match of spin quantum numbers in each layer. Meanwhile, the frequencies wg2, wg3, and wg4 in middle of other energy gaps increase monotonously with increasing spin quantum numbers. When the spin quantum numbers in each layer are same, the frequencies wg1, wg2, wg3, and wg4 all increase monotonously with increasing interlayer exchange couplings.展开更多
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
目的为了深入研究X Y Z模型 各向异性亚铁磁性Heisenberg系统下复式正方晶格的自旋波解以及对系统的热力学性质和磁性质.方法利用Heisenberg交换作用模型、格林函数法研究了系统的自旋波解.结果系统的磁振子能谱随各向异性参数(X1,X2,X3...目的为了深入研究X Y Z模型 各向异性亚铁磁性Heisenberg系统下复式正方晶格的自旋波解以及对系统的热力学性质和磁性质.方法利用Heisenberg交换作用模型、格林函数法研究了系统的自旋波解.结果系统的磁振子能谱随各向异性参数(X1,X2,X3)、自旋量子数(Sa,Sb)在第一布里渊区中的主要对称点线上随波矢k的变化规律.结论系统的磁振子能谱的排序与自旋量子数(Sa,Sb)、各向异性参数(X1,X2,X3)、第一布里渊区中的位置无关,在布里渊区边界附近各向异性参数对磁振子能谱没有影响.X1=1 0时在Γ点E2=E1(二重简并),E2、E4随X1的增加而下降.磁振子能谱E4、E2与E1、E3对于E/J=0线对称分布.Sa对E2、E1几乎没有影响,但对E4、E3有显著的影响.展开更多
The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,...The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.展开更多
基金Supported by the Natural Science Foundation of Liaoning Province of China under Grant No. 20062040
文摘The frequency in middle of magnon energy band in a five-layer ferromagnetic superlattice is studied by using the linear spin-wave approach and Green＇s function technique. It is found that four energy gaps and corresponding four frequencie in middle of energy gaps exist in the magnon band along Kx direction perpendicular to the superlattice plane. The spin quantum numbers and the interlayer exchange couplings all affect the four frequencies in middle of the energy gaps. When all interlayer exchange couplings are same, the effect of spin quantum numbers on the frequency wg1 in middle of the energy gap Δw12 is complicated, and the frequency wg1 depends on the match of spin quantum numbers in each layer. Meanwhile, the frequencies wg2, wg3, and wg4 in middle of other energy gaps increase monotonously with increasing spin quantum numbers. When the spin quantum numbers in each layer are same, the frequencies wg1, wg2, wg3, and wg4 all increase monotonously with increasing interlayer exchange couplings.
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.
文摘目的为了深入研究X Y Z模型 各向异性亚铁磁性Heisenberg系统下复式正方晶格的自旋波解以及对系统的热力学性质和磁性质.方法利用Heisenberg交换作用模型、格林函数法研究了系统的自旋波解.结果系统的磁振子能谱随各向异性参数(X1,X2,X3)、自旋量子数(Sa,Sb)在第一布里渊区中的主要对称点线上随波矢k的变化规律.结论系统的磁振子能谱的排序与自旋量子数(Sa,Sb)、各向异性参数(X1,X2,X3)、第一布里渊区中的位置无关,在布里渊区边界附近各向异性参数对磁振子能谱没有影响.X1=1 0时在Γ点E2=E1(二重简并),E2、E4随X1的增加而下降.磁振子能谱E4、E2与E1、E3对于E/J=0线对称分布.Sa对E2、E1几乎没有影响,但对E4、E3有显著的影响.
基金Supported by the Natural Science Foundation of Liaoning Province of China under Grant No.20062040
文摘The specific heats of both a two-layer ferromagnetic superlattice and a two-layer ferrimagnetic one arestudied.It is found that the spin quantum numbers,the interlayer and intralayer exchange couplings,the anisotropy,theapplied magnetic field,and the temperature all affect the specific heat of these superlattices.For both the ferromagneticand ferrimagnetic superlattices,the specific heat decreases with increasing the spin quantum number,the absolutevalue of interlayer exchange coupling,intralayer exchange coupling,and anisotropy,while it increases with increasingtemperature at low temperatures.When an applied magnetic field is enhanced,the specific heat decreases in the two-layerferromagnetic superlattice,while it is almost unchanged in the two-layer ferrimagnetic superlattice at low fieldrange at low temperatures.
