Charge dynamics in thermally and doping induced insulator-metal transitions of (Ti1-xVx)2O3

TL;DR

This study investigates charge dynamics in (Ti1-xVx)2O3 across insulator-metal transitions induced by temperature and doping, revealing how optical properties and bond lengths change with these transitions.

Contribution

It provides detailed insights into the charge transport and optical conductivity changes during thermally and doping-induced IMTs in (Ti1-xVx)2O3, highlighting the role of band-crossing and hole-doping.

Findings

Optical conductivity peaks vary with temperature and doping, linked to Ti-Ti dimer bond length.

IMTs are driven by increased carrier density via band-crossing and hole-doping.

The IMTs do not involve a complete collapse of the Mott gap, unlike canonical correlated oxides.

Abstract

Charge dynamics of (Ti1-xVx)2O3 with x=0-0.06 has been investigated by measurements of charge transport and optical conductivity spectra in a wide temperature range of 2-600K with the focus on the thermally and doping induced insulator-metal transitions (IMTs). The optical conductivity peaks for the interband transitions in the 3d t2g manifold are observed in the both insulating and metallic states, while their large variation (by ~0.4 eV) with change of temperature and doping level scales with that of the Ti-Ti dimer bond length, indicating the weakened singlet bond in the course of IMTs. The thermally and V-doping induced IMTs are driven with the increase in carrier density by band-crossing and hole-doping, respectively, in contrast to the canonical IMT of correlated oxides accompanied by the whole collapse of the Mott gap.