Prediction of nodal-line semimetals in two-dimensional black phosphorous films

• Main Authors: Xiaojuan Liu, Hairui Bao, Yue Li, Zhongqin Yang
• Format: Article
• Language: English
• Published: Nature Publishing Group 2020-12-01
• Series: Scientific Reports
• Online Access: https://doi.org/10.1038/s41598-020-78451-7

Abstract Semimetals are a new kind of quantum materials, in which the conduction and valence bands cross each other near the Fermi level. Based on density-functional theory calculations and symmetry analysis, we propose nodal-line semimetals in layered stacked black phosphorus (BP) films which are designed to have a mirror symmetry lying in the BP layer plane and thus rendering them different from the BP film systems previously studied. A closed nodal-line degenerate band can appear around the Fermi level in the BP films after a biaxial compressive strain is applied. The calculated Z2 number of Z2 =  − 1 indicates the robustness of the nodal-line semimetals obtained in the BP films, protected by the in-plane mirror symmetry. Intriguingly, with the increase of the film thickness, a smaller biaxial compressive strain is required to produce the nodal-line semimetals, more accessible in experiments. Our results provide a promising route to carrying out the nodal-line semimetals based on various two-dimensional materials.