Substrate and crystal orientation dependent structural and ferroelectric properties of Sm doped BiFeO$_{3}$ thin films at the morphotropic phase boundary

Previously, we had reported on the universal trend in structural transition in rare-earth-doped BiFeO$_{3}$ films grown on (100) SrTiO$_{3}$ substrates [1]. At this boundary, we observe double hysteresis loops in PE hysteresis loops due to an electric-field-induced transition and substantial enhancement in dielectric constant and piezoelectric coefficient. In this study, we have investigated substrate dependence of the structural and ferroelectric properties of (Bi,Sm)FeO$_{3}$ by growing the composition spreads on various substrates. We chose (100), (110) and (111) SrTiO$_{3}$, (100) LSAT and (110) DyScO$_{3}$ as substrates. Scanning x-ray diffraction reveals that all the fabricated spread films exhibit the rhombohedral to orthorhombic structural transition at Sm 14\%, independent on the type of the substrates. This confirms that the observed structural transition is a bulk property of the (Bi,Sm)FeO$_{3}$ system. The detailed correlations between the structural properties and ferroelectric properties depending on the type of the substrate will be discussed. This work is supported by DMR, NSF MRSEC DMR, ARO and the W. M. Keck Foundation.\\[4pt] [1] S. Fujino et al., APL 92, 202904 (2008).