We simulate boron on Pb(110) surface by using ab initio evolutionary methodology. Interestingly, the two-dimensional (2D) Dirac Pmmn boron can be formed because of good lattice matching. Unexpectedly, by increasing the thickness of 2D boron, a three-bonded graphene-like structure (P2_1/c boron) was revealed to possess double anisotropic Dirac cones. It is 20 meV/atom lower in energy than the Pmmn structure, indicating the most stable 2D boron with particular Dirac cones. The puckered structure of P2_1/c boron results in the peculiar Dirac cones, as well as substantial mechanical anisotropy. The calculated Young's modulus is 320 GPa.nm along zigzag direction, which is comparable with graphene.
@article{arxiv.1705.00257,
title = {Two-dimensional boron on Pb (110) surface},
author = {Xin-Ling He and Xiao-Ji Weng and Yue Zhang and Zhisheng Zhao and Zhenhai Wang and Bo Xu and Artem R. Oganov and Yongjun Tian and Xiang-Feng Zhou and Hui-Tian Wang},
journal= {arXiv preprint arXiv:1705.00257},
year = {2017}
}