Photoinduced dynamics of Ti2O3

The photoinduced dynamics of ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ with a corundum structure have been investigated by pump-probe optical spectroscopy. It is found that a peak in the optical spectrum corresponding to excitations within Ti-Ti dimers is suppressed when a laser pulse is applied at room temperature, indicating a photoinduced phase transition from the low-temperature insulating state to the high-temperature conducting state in ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$. In addition, the oscillation of reflectivity with time is observed, which can be explained by a strain wave generated by a laser pulse applied to the sample surface. The dependence of the oscillation on the direction of the surface indicates that the change in the $c$ lattice constant parallel to the Ti-Ti dimers plays an important role in the phase transition.