Deposition of Al onto the Si͑111͒7ϫ7 surface held at temperatures ranging from 475 to 600°C has been found to result in the formation of a superlattice of the identical-size nanoclusters ͑magic clusters͒. The Al magic clusters appear to have the structure similar to that reported recently for the magic clusters of Ga and In on Si͑111͒: each cluster contains six metal atoms linked by three Si atoms. The present results reveal that at the early stages of deposition all the group III metals demonstrate a distinct tendency for the formation of the magic clusters on Si surfaces.

A one-atom-layer compound made of one monolayer of Tl and one-third monolayer of Pb on a Si(111) surface having √3×√3 periodicity was found to exhibit a giant Rashba-type spin splitting of metallic surface-state bands together with two-dimensional superconducting transport properties. Temperature-dependent angle-resolved photoelectron spectroscopy revealed an enhanced electron-phonon coupling for one of the spin-split bands. In situ micro-four-point-probe conductivity measurements with and without magnetic field demonstrated that the (Tl, Pb)/Si(111) system transformed into the superconducting state at 2.25 K, followed by the Berezinskii-Kosterlitz-Thouless mechanism. The 2D Tl-Pb compound on Si(111) is believed to be the prototypical object for prospective studies of intriguing properties of the superconducting 2D system with lifted spin degeneracy, bearing in mind that its composition, atomic and electron band structures, and spin texture are already well established.

We report a comparative study of the synthesis and the structural and electronic properties of hexagonal boron nitride (h-BN) and graphene layers grown on the Ir(111) surface. By performing photoemission (PE) experiments time-dependently and supplementing them by low-energy electron diffraction (LEED) data, we demonstrate the differences and similarities of their formation, and we show the temperature regimes which allow these materials to be created with high crystalline quality. It has been demonstrated that synthesis at low temperatures leads to the formation of disordered domains of h-BN as well as graphene flakes on the metallic surface. The LEED patterns of such samples reveal a complex structure which indeed can be easily interpreted by using the model presented here. The angle-resolved PE study of h- BN/Ir(111) demonstrates the presence of replicated electronic states, which are quite similar to those detected and widely discussed for the graphene/Ir(111) system. On the basis of these results and the corresponding model calculations, we argue that the appearance of these replicated bands is mainly caused by the geometrical corrugation of the system.