M. Nagira

Ti 3d orbital change across metal-insulator transition in Ti2O3 : Polarization-dependent soft X-ray absorption spectroscopy at Ti 2p edge

The Ti 3 d electronic structure of Ti 2 O 3 across metal–insulator transition (MIT) has been investigated by means of polarization-dependent soft X-ray absorption spectroscopy (XAS) at the Ti 2 p edge. The XAS spectra exhibit a remarkable linear dichroism (LD) between the polarization vectors of the incident light parallel and perpendicular to the Ti ion pair along the c -axis. LD intensity is significantly reduced at 520 K in the metallic phase in comparison with that at 300 K in the insulating phase, indicating a large change in a 1 g and e g π orbital occupations. The results are qualitatively consistent with a recent theory, where the MIT is due to the change of the 3 d electronic configuration in the Ti pair along the c -axis driven by a change in the t 2 g level splitting relative to the on-site exchange interaction.