The effects of spin-orbit (SOC) and electron-phonon coupling on the collective excitation of doped monolayer ${\mathrm{Sb}}_2$ are investigated using density functional and many-body perturbation theories. The spin-orbit coupling is exclusively important for the monolayer ${\mathrm{Sb}}_2$ and it leads to the modification of the electronic band structure. In particular, plasmon modes of monolayer ${\mathrm{Sb}}_2$ are quite sensitive to the SOC and are characterized by very low damping rates, owing to small electron-phonon scatterings. Our results show how plasmons in antimonene are significantly less damped compared to monolayer graphene when plasmon energies are larger than 0.2 eV due to smaller plasmon-phonon coupling in the former material.

• Received 16 February 2020
• Revised 22 April 2020
• Accepted 23 April 2020

DOI:https://doi.org/10.1103/PhysRevB.101.205412