Composition dependent electronic structure effects in Nd1−x Sr x TiO3

Abstract

The development of the electronic structure in Nd1−x Sr x TiO3 as a function of x was investigated using resonant photoelectron spectroscopy. Attention is focussed indication of changes in the Ti 3d-O2p hybridization and on electron-electron correlation effects evident in the Ti 3d intensity within ∼ 3 eV of the Fermi level (E F). The energetic position of the Ti 3d intensity signals the importance of electron correlation effects. The total intensity in this region is found to correlate linearly with composition and changes in the spectral structure are discussed in terms of the one-electron spectral function. For x < 0.25 (insulating or semiconducting compositions), only incoherent intensity associated with the lower Hubbard band is present. Additional intensity, attributed to a coherent quasiparticle contribution, appears at the composition of the metal-insulator transition, x < 0.25. Ti 3d intensity also occurs in the higher binding energy region of the predominantly O 2p band due to Ti 3d O-2p hybridization. Composition-dependent changes in this region are analyzed to determine changes in the Ti 3d-O2p hybridization with composition and structure.