%0 Journal Article
%T Terahertz conductivity of twisted bilayer graphene
%A Xingquan Zou
%A Jingzhi Shang
%A Jianing Leaw
%A Zhiqiang Luo
%A Liyan Luo
%A Chan La-o-vorakiat
%A Liang Cheng
%A Haibin Su
%A Jian-Xin Zhu
%A Yanpeng Liu
%A Kian Ping Loh
%A A. H. Castro Neto
%A Ting Yu
%A Elbert E. M. Chia
%J Physics
%D 2013
%I arXiv
%R 10.1103/PhysRevLett.110.067401
%X Using terahertz time-domain spectroscopy, the real part of optical conductivity [$\sigma_{1}(\omega)$] of twisted bilayer graphene was obtained at different temperatures (10 -- 300 K) in the frequency range 0.3 -- 3 THz. On top of a Drude-like response, we see a strong peak in $\sigma_{1} (\omega)$ at $\sim$2.7 THz. We analyze the overall Drude-like response using a disorder-dependent (unitary scattering) model, then attribute the peak at 2.7 THz to an enhanced density of states at that energy, that is caused by the presence of a van Hove singularity arising from a commensurate twisting of the two graphene layers.
%U http://arxiv.org/abs/1302.4185v1