Valence-EELS analysis of local electronic and optical properties of PMN–PT epitaxial film

This study investigated local electrical and optical properties of Pb(Mg0.39Nb0.61)–0.34 mol%PbTiO3 solid solution (PMN–PT) film stacked on Si (0 0 1) wafer with (La,Sr)CoO3−x/CeO2/YSZ buffer layers. TEM-VEELS analysis of the PMN–PT thin film, which was grown epitaxially on the Si substrate with two coexisting phases of pseudocubic and tetragonal morphology, was firstly conducted using the TEM-VEELS method. The ELF has shown a bulk plasmon peak and two interband plasmon peaks. The interband transition has been interpreted in comparison with the joint density of state obtained from the measured dielectric function and the density of state calculated by the density functional theory. The interband transition from the O 2p band to Nb 4d/Ti 3d bands determines the optical properties around the band gap. The optical absorption of PMN–PT film has shown the band gap of 3.5 ± 0.2 V. The refractive index derived from the TEM-VEELS analysis in the nano-region of the film has agreed with that obtained with the conventional optical measurement from the macroscopic region.