Effects of quasiparticle screening on collective modes: Incommensurate charge-density-wave systems.
Effects of quasiparticle screening on collective modes: Incommensurate charge-density-wave systems.
复制标题
准粒子筛选对集体模式的影响：不相称的电荷密度波系统。
DOI：
10.1103/physrevb.36.5476
复制
发表时间：
1987
期刊：
影响因子：
--
通讯作者：
Takada
中科院分区：
文献类型：
--
作者：
Wong;Takada
通过在通常的Frölich哈密顿量中加入库仑相互作用项，发现了不相称电荷密度波系统中相模的色散。在长波长范围内，光谱由光分支和声分支组成，在低温下，光分支越来越占主导地位，在高温下，声分支越来越占主导地位。由于准粒子的有效质量小，光模频率得到了提高。为了增加波数，两个分支合并在一起，超过这个分支，单个分支接近光频率(${(3/2)}^{1/2}$${\ensuremath{\omega}}_{\ensuremath{\alpha}}$，其中${\ensuremath{\omega}}_{\ensuremath{\alpha}}$是幅模频率。在声学分支中，凝聚态电子和准粒子的电荷密度相外振荡，相互平衡，而在光学分支中，两者的电荷密度都相内振荡。
By including the Coulomb interaction term in the usual Fr\"olich Hamiltonian, the dispersion of the phase mode in incommensurate charge-density-wave systems is found. In the long-wavelength limit, the spectrum consists of an optic branch and an acoustic branch, with the optic branch increasingly dominant at low temperatures and the acoustic branch dominant at high temperatures. The optic-mode frequency is enhanced because of the small effective mass of the quasiparticles. For increasing wave numbers, the two branches merge together, beyond which the single branch approaches an optic frequency (${(3/2)}^{1/2}$${\ensuremath{\omega}}_{\ensuremath{\alpha}}$, where ${\ensuremath{\omega}}_{\ensuremath{\alpha}}$ is the amplitude-mode frequency. In the acoustic branch, the charge densities of the condensed electrons and the quasiparticles oscillate out of phase, balancing each other, while in the optic branch, both components oscillate in phase.