Structural and optical properties of epitaxial $BaTiO3$ thin films grown on $GdScO3(110)$

We have prepared 1-μm-thick epitaxial $BaTiO3$ thin films on $GdScO3(110)$ using pulsed laser deposition. The structural perfection of the films was revealed by a rocking curve width of Δω=0.13° for the 002 $BaTiO3$ reflection and a Rutherford backscattering spectrometry/channeling minimum yield, $χmin,$ of 0.5% measured for the Ba signal behind the surface peak. High-resolution transmission electron microscopy revealed an epitaxial relationship between $BaTiO3$ and $GdScO3$ and a sharp interface between the substrate and the film. The refractive index of the $BaTiO3$ film was $no=2.329±0.002$ and $ne=2.307±0.002$ at a wavelength of 632.8 nm and $no=2.248±0.002$ and $ne=2.228±0.002$ at a wavelength of 1523 nm. The optical losses were less than 2 dB/cm at a wavelength of 632.8 nm.