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Free keywords:
Binary alloys, Circular dichroism spectroscopy, Corundum, Magnesia, Magnesium, Metal insulator boundaries, Metal insulator transition, Semiconductor insulator boundaries, Titanium, X ray absorption spectroscopy, Hole doping effects, Hole-doping, Linear dichroism, Metal-insulators transitions, Mg substitution, Orbital anisotropy, Singlet state, Soft x-ray absorption spectroscopies, State-formation, X-ray absorptions, Dichroism
Abstract:
Corundum oxide Ti2O3 shows the metal-insulator transition around 400-600 K accompanying the nearest Ti3+-Ti3+ bond (a1ga1g singlet state) formation along the c axis. In order to clarify the hole-doping effect for the a1ga1g singlet bond in Ti2O3, we investigated Ti 3d orbital anisotropy between corundum-type Ti2O3 and ilmenite-type MgTiO3 using linear dichroism of soft x-ray absorption spectroscopy of the Ti L2,3 edge. From the linear dichroic spectral weight in MgyTi2-yO3, we confirmed that the a1ga1g state is dominant not only in y=0.01 (almost Ti2O3), 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 a1g to egπ. © 2023 American Physical Society.
