Phonon Properties, Thermal Expansion, and Thermomechanics of Silicene and Germanene

Abstract

We report a hierarchical first-principles investigation on the entangled effects of lattice dimensionality and bond characteristics in the lattice dynamics of silicene and germanene. It is found that bond bending (stretching) negatively (positively) contributes to Grüneisen constant, which results in the negative acoustic (positive optical) Grüneisen constant. The layer thickening (bond weakening) caused by chemical functionalization tends to increase (decrease) the acoustic (optical) Grüneisen constant, due to the increased (decreased) bond-stretching effect. The excitation of the negative-$\gamma$ modes results in negative thermal expansion, while mode excitation and thermal expansion compete with each other in thermomechanics. The sensitive structural and electronic responses of silicene and germanene to functionalization help us to derive a generic physical picture for two-dimensional lattice dynamics.

to be Published in Phys. Rev. B

References in corpus (4)

• Electric Field Effect in Atomically Thin Carbon Films
• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Valley-Polarized Metals and Quantum Anomalous Hall Effect in Silicene
• Finite temperature lattice properties of graphene beyond the quasiharmonic approximation

Cited by in corpus (3)

• Comparative study of phonon spectrum and thermal expansion of graphene, silicene, germanene and blue phosphorene
• Anisotropic thermal expansion and thermomechanic properties of monolayer $\beta$-Te
• Phonons and Anomalous Thermal Expansion Behaviour in Crystalline Solids