Electronic Structure of Charge- and Spin-Controlled ${\mathrm{Sr}}_{1-(x+y)}{\mathrm{La}}_{x+y}{\mathrm{Ti}}_{1-x}{\mathrm{Cr}}_x{\mathrm{O}}_3$

We present the electronic structure of ${\mathrm{Sr}}_{1-(x+y)}{\mathrm{La}}_{x+y}{\mathrm{Ti}}_{1-x}{\mathrm{Cr}}_x{\mathrm{O}}_3$ investigated by high-resolution photoemission spectroscopy. In the vicinity of the Fermi level, it was found that the electronic structure was composed of a Cr $3d$ local state with the $t_{2g}^3$ configuration and a Ti $3d$ itinerant state. The energy levels of these Cr and Ti $3d$ states are well interpreted by the difference of the charge-transfer energy of both ions. The spectral weight of the Cr $3d$ state is completely proportional to the spin concentration $x$ irrespective of the carrier concentration $y$, indicating that the spin density can be controlled by $x$ as desired. In contrast, the spectral weight of the Ti $3d$ state is not proportional to $y$, depending on the amount of Cr doping.

Figure 1

Resonant PES spectra of $(0.2,0.15)$ in (a) the full valence-band and (b) the near-$E_{\mathrm{F}}$ region. The spectra are taken at 45.6 eV (dashed line) and 50.0 eV (solid line), which correspond to the Ti and Cr $3p\mathrm{\text{−}}3d$ on resonance, respectively.

Figure 2

(a) Valence-band spectra taken at 150 eV. (b) Same as (a) in the near-$E_{\mathrm{F}}$ region in an expanded scale. (c) Very near-$E_{\mathrm{F}}$ region spectra. (d) and (e) Intensity plots of the features $B$ and $A$, respectively. Spectral weight of features $B$ and $A$ is set to unity at $(0.1,0.1)$ and $(0.2,0.1)$. The integration windows are given in the text.

Figure 3

(a) Valence-band spectra of ${\mathrm{Sr}}_{0.6}{\mathrm{La}}_{0.4}{\mathrm{Ti}}_{0.8}{M}_{0.2}{\mathrm{O}}_3$ ($M=\mathrm{Cr}$, V) taken at 150 eV. (b) and (d) Schematic electronic structure of SLTCO compared with the analogues and the double perovskite ${\mathrm{Sr}}_2{\mathrm{FeMoO}}_6$. (c) Binding energy of spectral features and ${\Delta }_{\mathrm{eff}}$’s are plotted against the number of $3d$ electrons, where ${\Delta }_{\mathrm{eff}}$ for $M^{4+}$ includes an offset by 4.0 eV. Since the centroid of $A$ must be above $E_{\mathrm{F}}$, the upper error bar of the ${\mathrm{Ti}}^{4+}$ is expected to be large.