Phonon dispersion of silicene on ZrB2(0 0 0 1).

We measured the phonon dispersion of silicene (monolayer Si with a honeycomb lattice) on ZrB2(0 0 0 1) using high-resolution electron energy loss spectroscopy. The measured phonon dispersion was compared with ab initio density functional theory calculations for a silicene model with [Formula: see text] periodicity of the substrate. The most stable [Formula: see text] silicene structure, which is similar to the so-called 'planar-like' model (Lee C C et al 2013 Phys. Rev. B 88 165404) reproduced the observed phonon modes very well. The recently reported soft phonon around the [Formula: see text] point (Lee C C et al 2014 Phys. Rev. B 90 241402(R)) was not reproduced, either experimentally or theoretically. The calculated electronic structure revealed that the silicene was metallic on ZrB2(0 0 0 1) and semiconducting on ZrC(1 1 1).