Electronic structure of layered perovskite-related

Abstract

The electronic properties and the crystal structure of layered perovskite-related niobates (Formula presented) can be tuned by gradually changing the oxygen 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 (Formula presented) and (Formula presented) single crystals. ARPES shows a one-dimensional dispersion and a purely one-dimensional Fermi surface with a nesting vector (Formula presented) A strongly anisotropic electronic character appears in polarization-dependent O (Formula presented) NEXAFS as well. Local-density approximation (LDA) band-structure calculations support this dispersion behavior of the lowest-lying conduction band and find additional Fermi surface sheets with a more two-dimensional character. © 2000 The American Physical Society.