“M-shape” nanoscale friction anisotropy of phosphorene

In this work, molecular dynamics simulations are employed to explore the nanoscale friction anisotropy of phosphorene. We study the friction process of a diamond tip sliding against the phosphorene on the silicon substrate under different sliding directions. The results show that there exists a significant anisotropy in the friction force along different lattice orientations of phosphorene. The friction force exhibits “M-shape” which means the friction force is locally maximum along the 15° and 75° directions relative to the zigzag direction of phosphorene. It is proposed that this “M-shape” friction anisotropy is due to the difference of potential energy among different orientations arising from the unique structure of phosphorene and heterogeneous interaction with the substrate.