Structure and microstructure of La_1–xSr_xMnO₃ (x ≈ 0.16) films grown on a SrTiO₃(110) substrate

Abstract

The interface between La_1–x Sr _x MnO₃ (LSMO) epitaxial films grown by pulsed-laser deposition on the (110) surface of a SrTiO₃ single-crystal substrate has been investigated by high-resolution electron microscopy and by electron-energy-loss spectroscopy. The structure of the LSMO films is rhombohedral, a pseudocubic distortion of the perovskite structure. The films show microtwinning, which apparently acts as a mechanism of misfit strain relaxation without a need for the formation of interfacial dislocations. The interface exhibits corrugations formed by mutually perpendicular microfacets parallel to the cubic planes of the pseudocubic structure. Within the LSMO film, close to the interface, inclusions are formed; their lattice is coherent with that of the surrounding LSMO matrix. Energy-electron-loss spectroscopy suggests that the inclusions are lanthanum rich. A film growth scenario compatible with the observed phase separation is proposed.