Prediction of nodal-line semimetals in 2D ScX (X = P, As) with high stability and considerable fermi velocities

Abstract

The nodal–line structure provides higher carrier mobility, massless and special features in which the conduction band and the valence band cross at the Fermi level. The anisotropic nodal–line structure has the advantage of anisotropic Fermi velocity for novel 2D quantum device. Here we report two binary monolayers with anisotropic nodal–line based on first-principles calculation. Fully optimized ScX (X = P, As) structure can still keep good structural integrity at high temperature of 1000 K in ab initio molecular dynamics simulation. Besides, we analyze structural symmetry and wave function to illustrate the existence of nodal–line, the Young’s modulus and Poisson’s ratio of ScX show nice anisotropy. The Fermi velocities of ScX are larger than 10⁵ m/s, which are the same order of magnitude as graphene. This work provides novel candidates of nodal–line semimetals for massless and stable quantum devices.