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

The Ti 3d electronic structure of Ti2O3 across metal-insulator transition (MIT) has been investigated by means of polarization-dependent soft X-ray absorption spectroscopy (XAS) at the Ti 2p 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(1g) and e(g)(pi) orbital occupations. The results are qualitatively consistent with a recent theory, where the MIT is due to the change of the 3d electronic configuration in the Ti pair along the c-axis driven by a change in the t(2g) level splitting relative to the on-site exchange interaction.