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We have studied the electronic structure of the layered compound Td-WTe 2 experimentally using highresolution angle-resolved photoelectron spectroscopy, and theoretically using density-functional based augmented spherical wave calculations. Comparison of the measured and calculated data shows in general good agreement. The theoretical results reveal the semimetallic as well as metallic character of Td-WTe 2 ; the semimetallic character is due to a 0.5 eV overlap of Te 5p-and W 5d-like bands along ⌫-Y , while the metallic character is due to two classical metallic bands. The rather low conductivity of Td-WTe 2 is interpreted as resulting from a low density of states at the Fermi level.

High quality In2O3 single crystals of bcc structure were grown by chemical vapour transport. The temperature dependence of resistivity, Hall constant, and mobility yielded an electron density of n = 1.3 × 1019 cm−3. The transport properties showed characteristics best describable by the degenerate semiconductor model. The crystals were additionally investigated by high resolution angular resolved photoelectron spectroscopy (ARPES). Emission from the valence band and the partially filled conduction band at the Γ point yielded a direct bandgap of (2.7 ± 0.1)eV. The partially filled conduction band furthermore enabled the determination of its three dimensional Fermi surface and the effective masses m* by ARPES.

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Bi 2 Sr 2-x La x CuO 6+δ and Bi 2-y Pb y Sr 2-x La x CuO 6+δ high-T c superconductors in a wide doping range from overdoped to heavily underdoped were studied by x-ray absorption and photoemission spectroscopy. The hole concentration p was determined by an analysis of the Cu L 3 -absorption edge. Besides the occupied density of states derived from photoemission, the unoccupied density of states was determined from the prepeak of the O K-absorption edge. Both, the occupied as well as the unoccupied density of states reveal the same dependence on hole doping, i.e. a continuous increase with increasing doping in the hole underdoped region and a constant density in the hole overdoped region. By comparing these results of single-layer BSLCO with previous results on single-layer LSCO it could be argued that besides the localized holes on Cu sites the CuO 2 -planes consist of two types of doped holes, from which the so-called mobile holes determine the intensity of the prepeak of the O 1s absorption edge