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arXiv 1306.6273cond-mat.mes-hall
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非本征自支撑石墨烯中的声等离子体激元

Acoustic plasmons in extrinsic free-standing graphene

M. Pisarra, A. Sindona, P. Riccardi, V. M. Silkin, J. M. Pitarke

摘要:

除了传统的二维(2D)等离子体激元之外,预测声等离子体激元作为共存于非本征(掺杂或门控)石墨烯的非常相同的2D带中的两种类型的电子载流子的系统的集体运动而发生。这种新模式的起源在于存在于狄拉克点附近的石墨烯能带结构中的强各向异性。这种各向异性允许沿着γ-K方向以两种不同的费米速度移动的载流子共存,这导致两种集体振荡模式:其中两种类型的电子彼此同相振荡的一种模式[这是常规的2D石墨烯等离子体激元,其在长波长(q->0)处具有相同的色散,q1/2,作为2D自由电子气体的常规2D等离子体激元],并且在此发现的另一模式对应于低频声振荡[其能量在长波长处表现出对2D波数q的线性依赖性],其中两种类型的电子异相振荡。如果这一预测得到实验证实,它将代表声等离子体激元的第一次实现,声等离子体激元起源于两种类型的载流子共存于同一频带内的系统的集体运动。

英文摘要:

An acoustic plasmon is predicted to occur, in addition to the conventional two-dimensional (2D) plasmon, as the collective motion of a system of two types of electronic carriers coexisting in the very same 2D band of extrinsic (doped or gated) graphene. The origin of this novel mode resides in the strong anisotropy that is present in the graphene band structure near the Dirac point. This anisotropy allows for the coexistence of carriers moving with two distinct Fermi velocities along the Gamma-K direction, which leads to two modes of collective oscillation: one mode in which the two types of electrons oscillate in phase with one another [this is the conventional 2D graphene plasmon, which at long wavelengths (q->0) has the same dispersion, q^1/2, as the conventional 2D plasmon of a 2D free electron gas], and the other mode found here corresponding to a low-frequency acoustic oscillation [whose energy exhibits at long wavelengths a linear dependence on the 2D wavenumber q] in which the two types of electrons oscillate out of phase. If this prediction is confirmed experimentally, it will represent the first realization of acoustic plasmons originated in the collective motion of a system of two types of carriers coexisting within the very same band.

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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