Effects of Mn Substitution on the Thermoelectric Properties and Thermal Excitations of the Electron-doped Perovskite Sr sub( 1-x)La sub( x)TiO sub( 3)

We studied how Mn substitution affects the thermoelectric properties and thermal excitations of the electron-doped perovskite Sr sub( 1-x)La sub( x)TiO sub( 3) 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 Mn super( 3+) 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 Sr sub( 1-x)La sub( x)TiO sub( 3) near room temperature.