Electronic structures of twisted few-layer black phosphorus

Few-layer black phosphorus (BP), a gapped two-dimensional (2D) semi-Dirac material, has pseudospin features even in its semiconducting phase [1,2]. When its band gap is closed, few-layer BP has a semi-Dirac point, and when its band gap is inverted, it has two anisotropic Dirac cones [1-3]. Twisted bilayers of gapped 2D semi-Dirac materials may have interesting emergent phenomena due to directional mismatch of in-plane anisotropy of each layer. In our present work, we perform density functional theory (DFT) calculations of 90-degree twisted few-layer BP. We control the band gap of twisted few-layer BP by changing structural parameters and analyze electronic band structures near the chemical potential. We construct effective Hamiltonian based on DFT results and obtain relevant pseudospin representations. We also discuss effects of externally applied electric fields.