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arXiv 0908.2608cond-mat.mes-hallcond-mat.str-el
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电子-声子相互作用对石墨烯光谱的影响

Effect of electron-phonon interaction on spectroscopies in graphene

J. P. Carbotte, E. J. Nicol, S. G. Sharapov

摘要:

我们计算了电子-声子相互作用对石墨烯的电子态密度、准粒子性质和光学电导率的影响。在声子能量尺度上具有DOS常数的金属中,电子-声子重整化从修饰DOS中消失,然而,由于石墨烯中电子动力学的狄拉克性质,能带DOS在能量上是线性的,声子结构保留,这可以通过取能量导数来强调。化学势和狄拉克点的能量位置都有移动。此外,DOS可以从狄拉克点处的零值的线性依赖性改变为有限值的二次依赖性。光学散射率$1/τ$设定了光学电导率从其通用DC值$4e^2/πh$(当化学势和温度都是$\ll 1/2τ$时,在最简单的理论中预期)到其通用AC背景值$(σ_0=πe^2/2h)$的上升的能量标度。与普通金属一样,直流电导率保持非重整化,而交流值发生变化。下的带内德鲁德的光谱重量减少的质量重整化因子是有效的散射率。光学重量转移到一个荷斯坦声子辅助边带。由于泡利的阻挡,带间跃迁被急剧抑制,但也几乎恒定,低于重整化化学势值的两倍,并且还表现出声子辅助的贡献。在大能量下,通用背景电导率降低到低于$σ_0$。

英文摘要:

We calculate the effect of the electron-phonon interaction on the electronic density of states (DOS), the quasiparticle properties and on the optical conductivity of graphene. In metals with DOS constant on the scale of phonon energies, the electron-phonon renormalizations drop out of the dressed DOS, however, due to the Dirac nature of the electron dynamics in graphene, the band DOS is linear in energy and phonon structures remain, which can be emphasized by taking an energy derivative. There is a shift in the chemical potential and in the position in energy of the Dirac point. Also, the DOS can be changed from a linear dependence out of value zero at the Dirac point to quadratic out of a finite value. The optical scattering rate $1/τ$ sets the energy scale for the rise of the optical conductivity from its universal DC value $4e^2/πh$ (expected in the simplest theory when chemical potential and temperature are both $\ll 1/2τ$) to its universal AC background value $(σ_0=πe^2/2h)$. As in ordinary metals the DC conductivity remains unrenormalized while its AC value is changed. The optical spectral weight under the intraband Drude is reduced by a mass renormalization factor as is the effective scattering rate. Optical weight is transferred to an Holstein phonon-assisted side band. Due to Pauli blocking the interband transitions are sharply suppressed, but also nearly constant, below twice the value of renormalized chemical potential and also exhibit a phonon-assisted contribution. The universal background conductivity is reduced below $σ_0$ at large energies.

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