RbNiF3自旋波量子对的Raman散射谱理论分析

在温度由零度直到Néel温度的范围内讨论了RbNiF₃自旋波量子对的Raman散射谱。由一般的对称性原理及实验结果的分析导出磁性系统与辐射场相互作用哈密顿量的具体形式;应用推迟Green函数运动方程方法,得到散射截面的解析表达式;在自旋波量子对传播子中同时计入能量重正化和寿命的效应。最后,在适当的近似下用计算机作数值计算,在没有可调整参数的情况下得到了在Néel温度以下的Raman峰值位置和半宽度随温度的变化关系及各种温度下的Raman谱形,它们与实验结果符合得较好。 关键词：

THEORETICAL ANALYSIS OF THE TWO-MAGNON RAMAN SPECTRA OF RbNiF3

Two-magnon Raman spectra of RbNiF₃ are calculated for the temperature range between 0 K to Néel point T_N(= 133 K). From considerations of the general symmetry principle and the experimental results, we have derived the Hamiltonian of interaction between the magnetic system and the radiation field. The method of the equation of motion of retarded Green's function is used to obtain the analytic expression of the two-magnon Raman scattering intensity. In the two-magnon propagator, both the effects of energy renormalization and the life time have been taken into account. Finally, quantitative calculations are performed with proper approximations using computer. Although there are no adjustable parameters, the results account very well for the observed temperature dependence of both the. peak position and the line width in the range from 0 K up to T_N.