The great success of graphene has spurred huge interest in two-dimensional honeycomb lattices of post-carbon group-14 atoms, namely, Xenes. However, the synthesis of Xenes on supporting substrates remains a big challenge due to the problem of Xene–substrate interaction. Recently, Pb(111) layers have been proposed as potential supports for silicene, the silicon follower of graphene. Using scanning tunneling microscopy and spectroscopy supported by ab initio density functional theory calculations, we reveal the epitaxial growth of silicene nanosheets on ultrathin Pb(111) films. Direct deposition of silicon on the Pb substrate results in two different discrete Si phases: √3 × √3 covered and 1 × 1 uncovered silicene structures. Scanning tunneling microscopy and spectroscopy measurements clearly display an atomically resolved low-buckled silicene honeycomb lattice in the uncovered phase. The covered phase represents the case of the Si(111)√3 × √3–Pb reconstruction on the thinnest Si substrate in the form of a single silicene layer.

We report on the initial stage of growing of silicon nanostructures on Pb-induced √ 3 × √ 3 and √ 3 × √ 7 reconstructed Si(111) surfaces. The deposition of 0.75 monolayer of Si at a temperature of around 200 K results in Si nanoribbons a few-nanometers in length running in three equivalent high symmetry directions of Si(111) surface, as revealed by low temperature scanning tunneling microscopy measurements. The nanoribbons are predominantly 1.6 nm wide and show local √ 3 × √ 3 reconstruction. These findings are interpreted within the framework of silicene nanoribbons grown on a bare Si(111) surface.

A structural model of the recently observed silicene-like nanoribbons on a Pb-induced √3 × √3 reconstructed Si(111) surface is proposed. The model, which is based on first principles density functional theory calculations, features a deformed honeycomb structure directly bonded to the Si(111) surface underneath. Pb atoms stabilize the nanoribbons, as they passivate the uncovered substrate, thus lower the surface energy, and suppress the nanoribbon–substrate interaction. The proposed structural model reproduces well all the experimental findings.

The adsorption and substitution of transition metal atoms (Fe and Co) on Au-supported planar silicene have been studied by means of first-principles density functional theory calculations. The structural, energetic and magnetic properties have been analyzed. Both dopants favor the same atomic configurations with rather strong binding energies and noticeable charge transfer. The adsorption of Fe and Co atoms do not alter the magnetic properties of Au-supported planar silicene, unless a full layer of adsorbate is completed. In the case of substituted system only Fe is able to produce magnetic ground state. The Fe-doped Au-supported planar silicene is a ferromagnetic structure with local antiferromagnetic ordering. The present study is the very first and promising attempt towards ferromagnetic epitaxial planar silicene and points to the importance of the substrate in structural and magnetic properties of silicene.