Evolution of the optical properties and the electrical resistivity of CaMnO3 during the substitution of Mo for Mn ions |
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Authors: | E V Mostovshchikova S V Naumov A A Makhnev N I Solin S V Telegin |
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Institution: | 1. Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, ul. S. Kovalevskoi 18, Yekaterinburg, 620990, Russia
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Abstract: | The reflectance, the optical density, and the optical conductivity spectra of CaMn1 ? x Mo x O3 (x ≤ 0.07) polycrystals are studied over a wide spectral region. The substitution of Mo6+ ions for Mn4+ ions leads to a strong decrease in the first high-energy phonon band, which is related to vibrations in the MnO6 octahedron. The appearance of band-type charge carriers is detected in CaMn1 ? x Mo x O3 with x ≤ 0.04, and carrier localization is observed in CaMn0.93Mo0.07O3. This localization increases at T < 160 K, i.e., during the transition from the paramagnetic to the antiferromagnetic state with orbital ordering and a monoclinic structure. The optical conductivity spectrum of CaMn0.93Mo0.07O3 exhibits a strong shift of fundamental absorption bands, which is associated with a change in the band structure because of a decrease in the splitting of the 3d levels of Mn in the crystal field. |
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