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

We have prepared 1-μm-thick epitaxial ${\mathrm{BaTiO}}_3$ thin films on ${\mathrm{GdScO}}_3\text{(110)}$ using pulsed laser deposition. The structural perfection of the films was revealed by a rocking curve width of Δω=0.13° for the 002 ${\mathrm{BaTiO}}_3$ reflection and a Rutherford backscattering spectrometry/channeling minimum yield, ${\chi }_{\min },$ of 0.5% measured for the Ba signal behind the surface peak. High-resolution transmission electron microscopy revealed an epitaxial relationship between ${\mathrm{BaTiO}}_3$ and ${\mathrm{GdScO}}_3$ and a sharp interface between the substrate and the film. The refractive index of the ${\mathrm{BaTiO}}_3$ film was $n_o\text{=2.329±0.002}$ and $n_e\text{=2.307±0.002}$ at a wavelength of 632.8 nm and $n_o\text{=2.248±0.002}$ and $n_e\text{=2.228±0.002}$ at a wavelength of 1523 nm. The optical losses were less than 2 dB/cm at a wavelength of 632.8 nm.