Electronic States on the Clean and Oxygen-Covered Molybdenum(110) Surface Measured Using Time-of-Flight Momentum Microscopy
Sergii Chernov (Institut für Physik)

Recently a strongly spin-polarized surface state with linear dispersion resembling that of Dirac type was found on the already well-investigated W(110) surface. This rose the question of the existence of the same non-trivial electron state on other metal surfaces.
We present our investigation of surface electronic states on the Mo(110) surface, their dispersion and transformation upon surface oxidation. This system is isoelectronic to the case of W(110) but due to the lower atomic number the spin-orbit interaction responsible for local band gap formation is substantially decreased by a factor of 5. The Mo(110) surface was shown to exhibit a linearly dispersing state quite similar to the one on W(110), but within a smaller energy range of 120 meV, with the Dirac point lying in the center of a local band gap in k-space. The results show good agreement with theoretical calculations of the band structure and photoemission patterns for clean Mo(110).
The experimental investigations were performed with the help of a novel time-of-flight momentum microscopy technique. The fully parallel 3D acquisition scheme allowed to visualize the full surface Brillouin zone. Few eV binding energy range was measured within a single exposure of typically 30 minutes.