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arXiv 1208.2804cond-mat.mes-hall
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电子-声子耦合对近场光谱的影响

Impact of Electron-Phonon Coupling on Near-Field Optical Spectra

J. P. Carbotte, J. P. F. LeBlanc, Phillip E. C. Ashby

摘要:

石墨烯的有限动量转移($\boldsymbol{q}$)纵向光学响应$σ^L(\boldsymbol{q},ω)$在能量$ω=\hbar v_F q$处具有峰。这直接对应于相对于费米动量$k_F -q$的动量谱密度中的准粒子峰。包含耦合到一个声子模式在$ω_E$的结果,对于$ω<|ω_E|$,在一个恒定的电子-声子重整化的裸带的质量增强因子$(1+λ)$,这是其次是一个声子扭结在$ω_E$的额外的加宽开始。在这里,我们研究相应的变化,我们发现,继续直接跟踪重整化准粒子能量的光学准粒子峰,直到$q$是足够大的光学跃迁开始采样的声子扭结区域的色散曲线,在那里的线性动量损失的重整化狄拉克费米子色散曲线和对应的一个单一的准粒子能量丢失。然而,在$σ^L(\boldsymbol{q},ω)$中仍然存在类似于色散曲线的声子扭结的特征,这些特征可以通过$q$和$ω$的变化来观察。

英文摘要:

The finite momentum transfer ($\boldsymbol{q}$) longitudinal optical response $σ^L(\boldsymbol{q},ω)$ of graphene has a peak at an energy $ω=\hbar v_F q$. This corresponds directly to a quasiparticle peak in the spectral density at momentum relative to the Fermi momentum $k_F -q$. Inclusion of coupling to a phonon mode at $ω_E$ results, for $ω<|ω_E|$, in a constant electron-phonon renormalization of the bare bands by a mass enhancement factor $(1+λ)$ and this is followed by a phonon kink at $ω_E$ where additional broadening begins. Here we study the corresponding changes in the optical quasiparticle peaks which we find to continue to directly track the renormalized quasiparticle energies until $q$ is large enough that the optical transitions begin to sample the phonon kink region of the dispersion curves where linearity in momentum is lost in the renormalized Dirac Fermion dispersion curves and the correspondence to a single quasiparticle energy is lost. Nevertheless there remains in $σ^L(\boldsymbol{q},ω)$ features analogous to the phonon kinks of the dispersion curves which are observable through variation of $q$ and $ω$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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