Effects of Mn Substitution on the Thermoelectric Properties and Thermal Excitations of the Electron-doped Perovskite Sr1−xLaxTiO3

We studied how Mn substitution affects the thermoelectric properties and thermal excitations of the electron-doped perovskite Sr1−xLaxTiO3 by measuring its electrical and thermal transport properties, magnetization, specific heat, and inelastic neutron scattering. Slight Mn substitution with the lattice defects enhanced the Seebeck coefficient, perhaps because of coupling between itinerant electrons and localized spins or between itinerant electrons and local lattice distortion around Mn3+ ions, while it enhanced anharmonic lattice vibrations, which effectively suppressed thermal conductivity in a state of high electrical conductivity. Consequently, slight Mn substitution increased the dimensionless thermoelectric figure of merit for Sr1−xLaxTiO3 near room temperature.