Preparation and optical properties of single-crystalline CaCuO2 thin films with infinite layer structure

We have prepared single-crystalline CaCuO2 thin films with infinite layer structure by pulsed laser deposition and investigated their optical properties by light absorption and Raman scattering. We find that oscillator strength of the charge transfer excitations decreases with increasing the lattice parameter <f>c</f>. On the other hand, two-magnon Raman scattering is insensitive to the lattice parameter. These results indicate that excess oxygen incorporated under the relatively strong oxidative condition supplies localized holes into the CuO2 planes. Furthermore, the excess oxygen relaxes selection rule of the phononic Raman scattering in the infinite layer compounds. [Copyright &y& Elsevier]