利用自旋动力学研究面心立方铁磁晶体自旋波的解析解

只考虑到第三近邻自旋相互作用情况下,利用自旋动力学求解了三维面心立方体铁磁晶体磁振子谱(自旋波谱)的解析解.次近邻交换积分J2与最近邻交换积分J1的比η=J2/J1值越大,第三近邻交换积分J3与最近邻交换积分J1的比γ=J3/J1值越大,面心立方铁磁系统中磁振子能量越大,并且磁振子能谱主要被最近邻交换积分J1所决定.磁振子能量随波矢k的增加而增大,但是在BZ区的X点处的磁振子能量与η无关,这说明在X点处磁振子能量与次近邻交换积分J2无关,与最近邻交换积分J1相关和第三近邻交换积分J3相关.因此,对于三维面心立方铁磁晶体的磁激发而言,为了能够更加真实地反映其磁激发,至少得考虑到第三近邻交换积分J3.

Studied the Analytical Solution of Spin Wave in Three-Dimensional Face-Centered Cubic Ferromagnetic Crystal by Using Spin Dynamics

Only considered the third nearest-neighbors spin interaction,we exactly solved strict analytical solution of three-dimensional face-centered cubic ferromagnetic crystal magnon＇s spectrum（spin wave spectrum） by using spin dynamics.The magnon＇s energy in the face-centered cubic ferromagnetic crystal system increased with the increase of the ratio η（η=J2/J1） of the second nearest-neighbors exchange integral J2 to the nearest-neighbors exchange integral J1,and the ratio γ（γ=J3/J1） of the third nearest-neighbors exchange integral J3 to the nearest-neighbors exchange integral J1.The magnon＇s energy spectrum was mostly determined by the nearest-neighbors exchange integral J1.The magnon＇s energy increased with the increase of wave vector k.And magnon＇s energy that was at the point of X,was only related to nearest-neighbors exchange integral J1 and third nearest-neighbors exchange integral J3.Therefore,regarding as the magnetic excitation of three-dimensional face-centered cubic ferromagnetic crystal,in order to more veritably reflected the magnetic excitation of system,we must considered of the third nearest-neighbors exchange integral J3 at least.