D.A. Pudikov

Surface spin-polarized currents generated in topological insulators by circularly polarized synchrotron radiation and their photoelectron spectroscopy indication

A new method for generating spin-polarized currents in topological insulators has been proposed and investigated. The method is associated with the spin-dependent asymmetry of the generation of holes at the Fermi level for branches of topological surface states with the opposite spin orientation under the circularly polarized synchrotron radiation. The result of the generation of holes is the formation of compensating spin-polarized currents, the value of which is determined by the concentration of the generated holes and depends on the specific features of the electronic and spin structures of the system. The indicator of the formed spin-polarized current can be a shift of the Fermi edge in the photoelectron spectra upon photoexcitation by synchrotron radiation with the opposite circular polarization. The topological insulators with different stoichiometric compositions (Bi1.5Sb0.5Te1.8Se1.2 and PbBi2Se2Te2) have been investigated. It has been found that there is a correlation in the shifts and generated spin-polarized currents with the specific features of the electronic spin structure. Investigations of the graphene/Pt(111) system have demonstrated the possibility of using this method for other systems with a spin-polarized electronic structure.

Electronic structure of graphene on Ni(111) and Ni(100) surfaces

A comparative investigation of graphene prepared by cracking of propylene (C3H6) on nickel surfaces with different orientations, Ni(111) and Ni(100), has been carried out using angle-resolved photoemission spectroscopy. It has been shown that the graphene formed on the Ni(111) surface is well ordered on a large surface area, whereas the graphene on the Ni(100) surface has a well-defined domain structure. It has been found that the electronic structures of the two systems are similar to each other, and graphene is strongly bound to the nickel substrate. It has been demonstrated that the intercalation of a gold monolayer for the two systems leads to the formation of an electronic structure that is characteristic of quasi-free-standing graphene.

Nickel Adsorption on Bi 2 Se 3 Surface

The effect of the physical adsorption of nickel on a surface of a topological Bi2Se3 insulator on the electronic structure has been studied. The influence of the adsorbate on the chemical bond between Bi and Se atoms has been studied by X-ray photoelectron spectroscopy. It is shown as well that nickel atoms diffuse into the topological insulator volume at room temperature.

Adsorption of silicon atoms on the surface of the Au/W(110)

The possibility of formation of an ordered silicene-like structure on Au/W(110) surface has been considered using angle-resolved photoelectron spectroscopy and X-ray photoelectron spectroscopy. It is shown that the addition of silicon atoms results in a considerable distortion of the electron structure of the initial substrate, and the resulting electron structure cannot be attributed to silicene. The configuration of reflections in the low energy electron diffraction pattern indicates the formation of two-dimensional ordered silicon structures with a large number of multidirectional domains.