S. Massidda

Transport Properties of High-Tc Superconductors

Transport properties of Ba1-xKxBiO3 and Nd2-xCexCuO4 are calculated using the electronic energy band structure obtained with the local-density full-potential linearized augmented-plane-wave method. For Ba1-xKxBiO3, the calculated Hall coefficient RH has the correct (negative) sign. For Nd2-xCexCuO4, on the other hand, a positive Hall coefficient for the magnetic field oriented perpendicular to the Cu-O planes contrasts with a negative experimental value. Recent experiments, however, show a change of sign of this Hall coefficient at x=0.18 from negative to positive with increasing x, indicating a trend towards a regime where the conventional band-theoretical discription becomes in better agreement with experiment.

Structural and Electronic Properties of Narrow Gap Zincblende and Chalcopyrite Compounds

Indium compounds and corresponding epitaxially grown superlattices have provided good single crystals suitable for accurate experimental measurements and have added new interest to the study of the constituent bulk semiconductors and the II-IV-V 2 chalcopyrite crystal phases. This paper reports results of structural and electronic properties of narrow gap binary and ternary semiconductors determined selfconsistently from first principles using both the full potential linearized augmented plane wave (FLAPW) and norm-conserving pseudopotentials (PP) total-energy methods.

Local density valence band offset in GaAs/AlAs: Role of interface dipole

Abstract The valence band offset, ΔEV ,at the lattice-matched GaAs/AlAs(001) interface is derived from highly precise self- consistent all-electron local density band structure calculations of the (GaAs)n(AlAs)n(001) superlattices (with n ⩽ 3). Using the core levels as reference energies, we find that ΔEV = 0.50 ± 0.05 eV, in very good agreement with recent experimental results (ΔEV = 0.45 − 0.55 eV). The dependence of ΔEV on the superlattice thickness is studied and related to the interface charge redistribution which produces an interface dipole potential estimated to be ∼ 0.14 eV.