Photoemission from bulk bands along the surface normal of W(110)

Spin polarization of surface states on W(1 1 0): Combined influence of spin–orbit interaction and hybridization

“…Possible strong correlation effects among d electrons in Rashba systems and topological insulators could be important scientific targets. The surface electronic structure of W(1 1 0) was subject of numerous photoemission studies [40][41][42][43][44]. In particular, a surface resonance within a spin-orbit-induced symmetry gap was detected for normal emission.…”

On the preparation and electronic properties of clean W(110) surfaces

“…For example, the values of p ox range from 2 · 10 À8 mbar [14] up to 4 · 10 À6 mbar [1], T ann is between 1000 K [15] and 2000 K [6,8,12], and T f is anywhere between 2000 K [2,3,12] and 3000 K [6]. Although several criteria have been proposed as indicators of a high surface quality, such as the sharpness and low background intensity in low-energy electron diffraction (LEED) [3,17,22], the absence of C-related peaks in Auger electron (AES) or X-ray photo-emission spectra (XPS) [14,17,19], the absence of H-specific peaks in electron-energy loss spectra (EELS) [14,19], or the intensity of an occupied surface resonance at 1.4 eV below the Fermi level in photo-emission spectra (PES) [23,18], it remains unclear under which conditions the best W(1 1 0) surface quality can be obtained. While keeping the duration of annealing d fixed at about 30 min we have experimentally studied the topography and electronic properties of W(1 1 0) surfaces in dependence of the oxygen pressure p ox during annealing by means of scanning tunneling microscopy (STM) and spectroscopy (STS).…”

“…Comparison reveals that the actual parameters of the duration d, the oxygen partial pressure p ox , the annealing temperature T ann , and the flash temperature T f strongly vary between the above mentioned cleaning procedures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]22]. For example, the values of p ox range from 2 · 10 À8 mbar [14] up to 4 · 10 À6 mbar [1], T ann is between 1000 K [15] and 2000 K [6,8,12], and T f is anywhere between 2000 K [2,3,12] and 3000 K [6].…”

“…In order to clean the dense-packed W(1 1 0) surface from its main impurity, carbon (C), a variety of processes have been proposed [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. Common to these cleaning procedures are cycles of prolonged annealing in an oxygen atmosphere and subsequent short high-temperature treatments, so-called flashes.…”

Bond-order potential for simulations of extended defects in tungsten

“…This is in agreement with both experimental and theoretical studies which show that the environment of this surface does not differ significantly, both electronically and structurally, from the bulk and the surface does not undergo any reconstruction. 111,115 The ͑211͒ surface exhibits the most corrugated structure among the surfaces investigated, and the energy of this surface is substantially lowered by relaxation. In the relaxed structure of this surface the atoms are displaced not only in the direction perpendicular to the surface but also laterally in the ͓111͔ direction parallel to the surface.…”