Yan Jun, Zhang Yuanbo, Kim Philip, Pinczuk Aron
Department of Physics, Columbia University, New York, New York 10027, USA.
Phys Rev Lett. 2007 Apr 20;98(16):166802. doi: 10.1103/PhysRevLett.98.166802. Epub 2007 Apr 18.
Gate-modulated low-temperature Raman spectra reveal that the electric field effect (EFE), pervasive in contemporary electronics, has marked impacts on long-wavelength optical phonons of graphene. The EFE in this two-dimensional honeycomb lattice of carbon atoms creates large density modulations of carriers with linear dispersion (known as Dirac fermions). Our EFE Raman spectra display the interactions of lattice vibrations with these unusual carriers. The changes of phonon frequency and linewidth demonstrate optically the particle-hole symmetry about the charge-neutral Dirac point. The linear dependence of the phonon frequency on the EFE-modulated Fermi energy is explained as the electron-phonon coupling of massless Dirac fermions.
栅极调制低温拉曼光谱表明，当代电子学中普遍存在的电场效应（EFE）对石墨烯的长波长光学声子有显著影响。在这种二维碳原子蜂窝晶格中的电场效应会产生具有线性色散的载流子（称为狄拉克费米子）的大密度调制。我们的电场效应拉曼光谱展示了晶格振动与这些特殊载流子之间的相互作用。声子频率和线宽的变化从光学上证明了关于电荷中性狄拉克点的粒子 - 空穴对称性。声子频率对电场效应调制的费米能量的线性依赖性被解释为无质量狄拉克费米子的电子 - 声子耦合。
