Electronic structure of layered perovskite-related Sr1-yLayNbO3.5-x

The electronic properties and the crystal structure of layered perovskite-r elated niobates Sr1-yLayNbO3.5-x can be tuned by gradually changing the oxy gen stoichiometry. We have studied the electronic structure of this series in detail by angle-integrated and angle-resolved (ARPES) photoemission and x-ray absorption (NEXAFS) on SrNbO3.45 and Lao(0.1)Sr(0.9)NbO(3.39) single crystals. ARPES shows a one-dimensional dispersion and a purely one-dimensi onal Fermi surface with a nesting vector 2k(F)=0.56 Angstrom(-1). A strongl y anisotropic electronic character appears in polarization-dependent O 1s N EXAFS as well. Local-density approximation (LDA) band-structure calculation s support this dispersion behavior of the lowest-lying conduction band and find additional Fermi surface sheets with a more two-dimensional character.