Figure 1

Schematic electronic structures near $E_F$ within band theory (a), when correlation effects are included for the conduction electrons (b), and within a model including various screening channels (c).Reuse & Permissions

Figure 2

O $1s$ (a) and Ti $2p_{3/2}$ (b) core-level spectra.Reuse & Permissions

Figure 3

Resonant PES at the Ti $2p_{3/2}$ absorption edge. (a) Ti $2p_{3/2}$ XAS of STO:Nb and STO. (b) Valence-band spectra of STO:Nb at the Ti $2p_{3/2}$ absorption edge. The intensities were normalized to the photon flux (post-focusing mirror current). The labels on the spectra (B to F) correspond to photon energies indicated in (a). (c) Take-off-angle dependence of the valence-band spectra taken in the angle-integrated mode at $h\nu =458.1\mathrm{eV}$. Spectra were normalized to the $\sim 11\mathrm{\text{−}}\mathrm{eV}$ peak area (colored area.) (d) Dispersion recorded in the angle-resolved mode along a trace in the momentum space shown by a dotted line in panel (e). Black/white corresponds to high/low intensity. Triangles indicate electron pockets detected around the $\Gamma$ points. Inset in (e) defines $\theta$ and coordinate of the momentum vector.Reuse & Permissions

Figure 4

Resonant PES at the O $1s$ absorption edge. (a) O $1s$ XAS of STO:Nb and STO. The structures at $h\nu =530.9$, 533.2, and 534.5–538.5 eV corresponds to O $1s$ core-electron excitation into O $2p$ states hybridized with Ti $3d$ $t_{2g}$, Ti $3d$ $e_g$, and Sr $5d$ states, respectively. (b) Valence-band spectra at the O $1s$ absorption edge. The labels on the spectra (H to V) correspond to the photon energies indicated in (a). The triangles in the left panel indicate the O $K{L}_{2,3}{L}_{2,3}$ Auger peak positions. The red (light gray) and blue (dark gray) area in the right panel indicate positive and negative differences to the 531.6-eV spectrum. The structures around 20 and 22 eV are due to Sr $4p$ and O $2s$ core levels, respectively. (c) CIS spectra. Each spectrum is normalized to the intensity at 525.6 eV and has an arbitrary offset.Reuse & Permissions

Figure 5

Ti $3d$ and O $2p$ PDOSs of STO:Nb near $E_F$.Reuse & Permissions