二维铁磁系统的纵向声频支声子的硬化  

Longitudinal acoustic phonon hardening in two-dimensional ferromagnetic system

作　　者：成泰民[1] 李林[2] 

机构地区：[1]沈阳化工学院数理系,辽宁沈阳110142 [2]东北大学理学院,辽宁沈阳110004

出　　处：《辽宁工程技术大学学报（自然科学版）》2009年第3期509-512,共4页Journal of Liaoning Technical University (Natural Science)

基　　金：国家自然科学基金资助项目(10647138);辽宁省科学技术计划资助项目(2006222002);辽宁省教育厅科学研究基金资助项目(20060667)

摘　　要：在二维正方Heisenberg铁磁系统的基础上建立了磁振子-声子相互作用模型.利用Matsubara格林函数理论研究了系统的纵向声频支声子激发,计算了布里渊区的主要对称点线上的纵向声频支声子色散曲线.发现在第一布里渊区,纵向声频支声子没有软化现象只有硬化现象,并且在布里渊区的边界区域纵向声频支声子硬化现象更加明显,又讨论了各项参数的变化对纵向声频支声子硬化的影响.对纵向声频支声子硬化起主要的是磁振子-声子耦合强度、材料的德拜温度ΘD、温度。在有限温度磁振子-声子相互作用下,只有横向声频支声子存在软化,而纵向声频支声子无软化只有硬化。A magnon-phonon interaction model is developed on the basis of two-dimensional Square Heisenberg ferromagnetic system. The longitudinal acoustic phonon excitation is investigated based on the Matsubara Green function theory. Also, the dispersion curve of longitudinal acoustic phonon is calculated, which is located on the main symmetric point and line in the Brillouin zone. It is found that there is hardening, no softening for longitudinal acoustic phonon in the first Brillouin zone. In particular, the hardening of longitudinal acoustic phonon is obvious at the edge of the Brillouin zone. The effects of various parameters on the hardening of longitudinal acoustic phonon are also discussed in this paper. Under the conditions of strong magnon-phonon coupling, low Debye temperature ΘD of the material, and high temperature （T〈TC）, the hardening of longitudinal acoustic phonon is enhanced. With the magnon-phonon interaction at certain temperature, the transverse acoustic phonon becomes softening, while the longitudinal acoustic phonon becomes hardening.

关 键 词：磁振子-声子相互作用 纵向声频支声子硬化 Matsubara格林函数理论 铁磁系统 

分 类 号：O482.523[理学—固体物理] O482.5[理学—物理]