Raman spectroscopy study of twisted tetralayer graphene

We present a systematic Raman study of twisted tetralayer graphene (t(2 + 2)LG), under excitation of two laser lines. In t(2 + 2)LG samples, top Bernal stacked bilayer graphene (2LG stands for Bernal-stacked bilayer graphene) twists different angle relative to bottom 2LG. It is found that 2D and 2D' peaks of t(2 + 2)LG show positive wavenumber shift relative to those of 2LG. We propose a simplified electronic band structure for t(2 + 2)LG; interlayer interaction-induced changing in electronic band structure can be used to understand the aforementioned spectral features. The electronic structures of t(2 + 2)LG samples are then probed from resonant Raman studies of 2D and 2D' peaks using two laser lines; electronic dispersions in t(2 + 2)LG samples are given. Our study facilitates understanding of twist angle-dependent electronic properties of tetralayer graphene superlattice. Copyright (C) 2016 John Wiley & Sons, Ltd.