Electronic and mechanical properties of Plumbene monolayer: A first-principle study

Abstract

Motivated by recent successful synthesis of plumbene, we used first-principle calculation to examine electrical and mechanical properties of plumbene monolayer under applying external strain and electric field and in the presence of Stone–Wales defect. The plumbene monolayer has the smallest Young modulus and ideal strength in group IV mono-elemental monolayers due to weaker bond length in comparison with their cousins. Tensile strain softens optical phonon modes so that the gap between acoustic and phonon modes are disappeared under high strains. Our findings demonstrate that the failure mechanism in plumbene monolayer is phonon instability. Plumbene has a Dirac band at the K point and a quadratic non-Dirac band at Γ point around the Fermi level which are gapped by taking into account the spin–orbit coupling. Biaxial tensile strain cannot open a band gap, whereas perpendicular electric field opens a small band gap at the K point. Our findings reveal that although plumbene monolayer can heal itself from Stone–Wales defects, a transition from a low-buckled monolayer to a high-buckled one is occurred. Our results suggest that the plumbene can be used in flexible electronics and is a promising candidate for quantum spin hall effect by tuning its electronic properties using external fields.