Influence of spin-orbit coupling on 2D strained plumbene monolayer

We have investigated the effect of spin-orbit coupling (SOC) on pristine and strained plumbene using density functional theory. Without SOC but under the application of biaxial strain, both unstrained and strained plumbene show metallic behaviour. With SOC, an indirect band gap opening of 0.47 eV is observed in unstrained plumbene. Under the effect of SOC, when the compressive strain (0 %–10 %) is applied to the system, the band gap gets reduced from 0.47 eV to 0 eV which shows the system changes from semiconducting to metallic. However, when tensile strain up to 10 % is applied with SOC, the bandgap changes from 0.47 eV to 0.66 eV and the band gap alignment is modified from indirect to direct gap transition. Our finding show that on the application of external strain, the effective masses of electron and hole get modified. The effective mass of electron and hole for pristine monolayer plumbene is 0.0195m₀ and 0.0237m₀ respectively. To check the stability of our pristine and strained structure, we have performed phonon calculation. Our finding show that the structures are stable under tensile strain (up to 10 %). This study provides a theoretical basis for realizing the strain regulation of monolayer plumbene.