Spin-orbit-interaction-induced surface resonance on W(011)

Adlayer influence on Dirac-type surface state at W(110)

In a combined experimental and theoretical study, we investigated how Fe and Co adlayers on W(110) affect the Dirac-type surface state (DSS). Angle-resolved photoelectron spectroscopy data show an increase in binding energy of 75 meV and 107 meV for Fe and Co, respectively. In order to identify the origin of the energy shift we performed first-principles calculations of the surface electronic structure. The inward surface relaxation of the uncovered W(110) surface is lifted by the adlayers. This structural change is one reason of the energy shift of the DSS. Furthermore, the Fe and Co adlayers change the surface potential, which results in an additional energy shift of the DSS.

Circular-polarized-light-induced spin polarization characterized for the Dirac-cone surface state at W(110) with C2v symmetry

The C_2v surface symmetry of W(110) strongly influences a spin-orbit-induced Dirac-cone-like surface state and its characterization by spin- and angle-resolved photoelectron spectroscopy. In particular, using circular polarized light, a distinctive k-dependent spin texture is observed along the \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\overline{{\boldsymbol{\Gamma }}{\boldsymbol{H}}}$$\end{document}ΓH¯ direction of the surface Brillouin zone. For all spin components P_x, P_y, and P_z, non-zero values are detected, while the initial-state spin polarization has only a P_y component due to mirror symmetry. The observed complex spin texture of the surface state is controlled by transition matrix element effects, which include orbital symmetries of the involved electron states as well as the geometry of the experimental set-up.

Spin-polarized Dirac-cone-like surface state with d character at W(110)

The surface of W(110) exhibits a Dirac-cone-like state with d character within a spin-orbit-induced symmetry gap. As a function of the wave vector parallel to the surface, it shows a nearly massless energy dispersion and a pronounced spin polarization, which is antisymmetric with respect to the Brillouin zone center. In addition, the observed constant energy contours are strongly anisotropic for all energies. This discovery opens new pathways to the study of surface spin-density waves arising from a strong Fermi surface nesting as well as d-electron-based topological properties.

An elastic "sieve" to probe momentum space: Gd chains on W(110)

Electron scattering conditions of one-dimensional nanostructures are explored in angle-resolved photoelectron spectroscopy. Tiny increments of the Gd submonolayer coverage on W(110) lead to strong modifications in the spectra. It is shown that the Gd overlayer represents an elastic superlattice of chains which performs a systematic mapping of the electronic band dispersion of the W substrate through a quasicontinuous series of umklapp wave vectors. Conversely, a single valence-band spectrum contains essential and precise structural information readily accessible by comparison to the band dispersion.

Photoemission from stepped W(110): initial or final state effect?

The electronic structure of the (110)-oriented terraces of stepped W(331) and W(551) is compared to the one of flat W(110) using angle-resolved photoemission. We identify a surface-localized state which develops perpendicular to the steps into a repeated band structure with the periodicity of the step superlattices. It is shown that a final-state diffraction process rather than an initial-state superlattice effect is the origin of the observed behavior and why it does not affect the entire band structure.