Photoinduced dynamics in doped Mott insulators with polaronic conduction: Ba2Ti13 O22 and BaxTi8 O16

To clarify the dynamics of polarons in doped Mott insulators, we performed pump-probe reflectivity measurements for two barium titanates, Ba2Ti13O22 and BaxTi8O16, with a noninteger average number of d electrons per Ti. We found that the photoinduced dynamics in Ba2Ti13O22 with a three-dimensional electronic structure is characterized by a broadening of the polaron-excitation peak immediately after photoirradiation, whereas that in BaxTi8O16 with a one-dimensional electronic structure is characterized by a change in the intensities of the polaron-excitation peak and charge-gap-excitation peak with time. This indicates that a difference in dimensionality results in different photoinduced dynamics of polarons in doped Mott insulators.