Faculty of Hydrotechnics, Department of Physics, University of Architecture, Civil Engineering and Geodesy, Sofia, Bulgaria.
J Phys Condens Matter. 2012 Jun 13;24(23):235401. doi: 10.1088/0953-8984/24/23/235401. Epub 2012 May 9.
We have studied the temperature and size dependence of the G and 2D phonon modes in graphene. It is shown that in a graphene monolayer the phonon energy decreases whereas the phonon damping increases with increasing temperature. The electron-phonon interaction leads to hardening whereas the fourth-order anharmonic phonon-phonon processes lead to softening of the phonon energy with increasing temperature. We have shown that the electron-phonon interaction plays an important role also by the dispersion dependence of the phonon G mode, by the observation of the Kohn anomaly. The G mode frequency decreases and damping increases, whereas the 2D phonon frequency and damping increase with increasing layer number. The temperature and size effects of the 2D mode are much stronger than those of the G mode.
我们研究了石墨烯中 G 模和二维声子模式的温度和尺寸依赖性。结果表明，在单层石墨烯中，随着温度的升高，声子能量降低，而声子阻尼增加。电子-声子相互作用导致声子能量变硬，而四阶非谐声子-声子过程导致声子能量随温度升高而变软。我们通过声子 G 模的色散依赖性以及观察到的科恩异常表明，电子-声子相互作用也起着重要作用。随着层数的增加，G 模的频率降低，阻尼增加，而二维声子的频率和阻尼增加。二维模式的温度和尺寸效应比 G 模强得多。
