Strain profile and polarization enhancement in Ba 0.5 Sr 0.5 TiO 3 thin films

The sensitivity of spontaneous polarization to epitaxial strain for both 10 and 50 nm thick Ba 0.5 Sr 0.5 TiO 3 (BSTO) ferroelectric thin films has been studied. Crystal truncation rod (CTR) profiles in the 00 L directions at different wavelengths, and grazing incidence diffraction (GID) in the 0 K 0 direction on a single crystal have been recorded. Modeling of the CTR data gives a detailed picture of the strain and provides clear evidence of the film out‐of‐plane expansion at the surface, an increase of the polarization, as well as a contraction at the interface. GID data confirm the fitting of the CTR, showing an in‐plane expansion of the BSTO film at the interface and a contraction at the surface.