Coherent motion of the electrons in the Bloch states is one of the fundamental concepts of the charge conduction in solid state physics. In layered materials, however, such a condition often breaks down for the interlayer conduction, when the interlayer coupling is significantly reduced by e.g. large interlayer separation. We report that complete suppression of coherent conduction is realized even in an atomic length scale of layer separation in twisted bilayer graphene. The interlayer resistivity of twisted bilayer graphene is much higher than the c-axis resistivity of Bernal-stacked graphite, and exhibits strong dependence on temperature as well as on external electric fields. These results suggest that the graphene layers are significantly decoupled by rotation and incoherent conduction is a main transport channel between the layers of twisted bilayer graphene.
@article{arxiv.1206.3410,
title = {Breakdown of the interlayer coherence in twisted bilayer graphene},
author = {Youngwook Kim and Hoyeol Yun and Seung-Geol Nam and Minhyeok Son and Dong Su Lee and Dong Chul Kim and S. Seo and Hee Cheul Choi and Hu-Jong Lee and Sang Wook Lee and Jun Sung Kim},
journal= {arXiv preprint arXiv:1206.3410},
year = {2015}
}