Strain-Induce Shift of the Crystal-Field Splitting of SrTiO3 Embedded in Scandate Multilayers

Strained SrTiO3 layers have become of interest, since the paraelectric-to-ferroelectric transition temperature can be increased to room temperature. A linear relationship between strain and energy splitting of the fundamental transitions in the fine structure of Ti L2,3 and O K edges is observed, that can be exploited to measure strain from electronic transitions, complementary to measuring local strain directly via high-resolution transmission electron microscopy (HRTEM) images. In particular, for both methods, the geometrical phase analysis performed on high-resolution images and the measurement of the energy splitting by energy loss spectroscopy, tensile strain of SrTiO3 layers was measured when grown on DyScO3 and GdScO3 substrates. The effect of strain on the electron loss near edge structure (ELNES) of the Ti L2,3 edge in comparison to unstrained samples is analyzed. Ab initio calculations of the Ti L2,3 and O K edge show a linear variation of the crystal field splitting with strain. Calculated and experimental values of the crystal field splitting show a very good agreement