LNCMI (CNRS, UJF, UPS, INSA) , BP 166, 38042 Grenoble Cedex 9, France.
Nano Lett. 2014 Mar 12;14(3):1460-6. doi: 10.1021/nl404588g. Epub 2014 Feb 5.
We report a comprehensive study of the tuning with electric fields of the resonant magneto-exciton optical phonon coupling in gated graphene. For magnetic fields around B ∼ 25 T that correspond to the range of the fundamental magneto-phonon resonance, the electron-phonon coupling can be switched on and off by tuning the position of the Fermi level in order to Pauli block the two fundamental inter-Landau level excitations. The effects of such a profound change in the electronic excitation spectrum are traced through investigations of the optical phonon response in polarization resolved magneto-Raman scattering experiments. We report on the observation of a splitting of the phonon feature with satellite peaks developing at particular values of the Landau level filling factor on the low or on the high energy side of the phonon, depending on the relative energy of the discrete electronic excitation and of the optical phonon. Shifts of the phonon energy as large as ±60 cm(-1) are observed close to the resonance. The intraband electronic excitation, the cyclotron resonance, is shown to play a relevant role in the observed spectral evolution of the phonon response.
我们报告了一项关于在门控石墨烯中通过电场调谐共振磁激子光学声子耦合的综合研究。对于约 B ∼ 25 T 的磁场，对应于基本磁声子共振的范围，可以通过调谐费米能级的位置来打开和关闭电子-声子耦合，以便通过泡利阻塞来阻止两个基本的 Landau 层激发。通过在极化分辨磁拉曼散射实验中研究光学声子响应，追踪了这种电子激发谱中深刻变化的影响。我们报告了在特定的 Landau 层填充因子值下观察到的声子特征的分裂，以及在声子的低能或高能侧上出现卫星峰，这取决于离散电子激发和光学声子的相对能量。在接近共振时，观察到声子能量的偏移高达 ±60 cm(-1)。证明了在观察到的声子响应的光谱演化中，带内电子激发和回旋共振起着重要作用。
