1. Linear dichroic x-ray absorption response of Ti-Ti dimers along the $c$ axis in Ti$_2$O$_3$ upon Mg substitution
- Author
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Okawa, M., Takegami, D., Christovam, D. S., Ferreira-Carvalho, M., Kuo, C. -Y., Chen, C. T., Miyoshino, T., Takasu, K., Okuda, T., Chang, C. F., Tjeng, L. H., and Mizokawa, T.
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Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Corundum oxide Ti$_2$O$_3$ shows the metal-insulator transition around 400-600 K accompanying the nearest Ti$^{3+}$-Ti$^{3+}$ bond ($a_{1g}a_{1g}$ singlet state) formation along the $c$ axis. In order to clarify the hole-doping effect for the $a_{1g}a_{1g}$ singlet bond in Ti$_2$O$_3$, we investigated Ti $3d$ orbital anisotropy between corundum-type Ti$_2$O$_3$ and ilmenite-type MgTiO$_3$ using linear dichroism of soft x-ray absorption spectroscopy of the Ti $L_{2,3}$ edge. From the linear dichroic spectral weight in Mg$_y$Ti$_{2-y}$O$_3$, we confirmed that the $a_{1g}a_{1g}$ state is dominant not only in $y=0.01$ (almost Ti$_2$O$_3$), but also in $y = 0.29$, indicating that the Ti-Ti bond survives against a certain level of hole doping. In $y=0.63$ corresponding to 46% hole doping per Ti, the $3d$ orbital symmetry changes from $a_{1g}$ to $e_g^{\pi}$., Comment: 5 pages, 5 figures
- Published
- 2023
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