交换积分变化对低温二维亚铁磁体能谱的影响

运用Heisenberg交换作用模型、spin-wave和Green＇s function方法研究了与低维有机磁性系统接近的二维正方晶格绝缘亚铁磁体的自旋波谱,并分析了不同方向上能谱谱线随系数J1/J2增加的变化规律,得到了如下结论：随磁性离子间的交换积分发生改变,磁振子能谱也发生了改变,沿某一方向能谱的变化与此方向上交换积分的变化密切相关。系统沿某一方向上交换积分的变化,导致形成所谓“自旋梯”时,谱线退化成5条能级,除最大的磁振子能谱线与最小的磁振子能谱线外,其余3条磁振子能谱线是二重简并的．系统的磁振子能谱E1、E3、E5、E7、与E6、E8、E2、E4关于E／J=0线对称分布。

The Spectrum of Two Dimension Ferrimagnet System in Low Temperature Affected by the Changing of Exchange Integration

The spin-wave spectrum of tetragonal crystal insulating ferromagnetic body in two dimension which is close to low dimensional organic magnet has been studied by means of spin-wave and Green's function within the Heisenberg exchange interaction model and the changing tendency of energy spectrum line in different orient with the coefficient J_1/J_2 has also been analyzed.We conclude that the energy spectrum of magnon changes with the exchange integral of magnetic ion.On a certain direction the change of energy spectrums relates closedly to the exchange integral in the direction.when the exchange integral of system varies,which leads to the formation of so call "spin ladder",spectrums degenerate to five level which are double degenerations except the maximum and the minimum energy spectrums line of magnon.The energy spectrums of systemic magnon E_1,E_3,E_5E_7 and E_6,E_8,E_2E_4 are distributed symmetrily according to E/J=0 line.