Charge carriers in optical spectra of electron-doped Ca1−xLaxMnO3 single crystals

Abstract Reflection spectra, resistivity, thermopower and the Hall effect of Ca 1− x La x MnO 3 (0.03⩽ x ⩽0.12) single crystals are studied. It is shown that the optical spectra are described by the Drude model. Concentration of the charge carriers is determined to be equal to doping ∼10 21 cm −1 . In contrast to lightly hole-doped manganites, in Ca 1− x La x MnO 3 conductivity has a band character. The optical effective mass m * of electrons and effective mass of density of states of the conduction band m d * are found to be about 2 – 3 m 0 and ∼ 10 m 0 , respectively. The width of the conduction band is estimated as ∼1 eV. The revealed difference between optical effective mass and effective mass of density of states is attributed to the anisotropic dispersion law and multivalley character of the conduction band.