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HL: Fachverband Halbleiterphysik

HL 50: HL Poster IV

HL 50.51: Poster

Donnerstag, 15. März 2018, 19:00–21:00, Poster B

atomic-scale observations of microstructure and local chemistry at the SrMnO3-SrTiO3 heterointerface — •Hongguang Wang, Vesna Srot, Yi Wang, Hans Boschker, Jochen Mannhart, and Peter A van Aken — Max Planck Institute for Solid State Research, 70569 Stuttgart, Germany

Oxide heterointerfaces show unprecedented physical properties such as electro-magnetic coupling, 2-dimensional electron gas and high-Tc superconductivity which cannot be found in their bulk analogies. It is the interfacial lattice reconstruction that induces these unexpected electronic states dominating the macroscopic characteristics. Therefore, atomic-scale observations of the oxide heterointerfaces are important for appropriate interpretation of these phenomena. Here, by using an aberration-corrected scanning transmission electron microscope (STEM) equipped with an electron energy-loss spectrometer (EELS), we performed atomic-scale investigations at the heterointerface between SrTiO3 (STO) and SrMnO3 (SMO). Atomic-resolved high-angle annular dark-field and annular bright-field images were used to evaluate the local lattice and oxygen distortions. The lattice structure analysis shows a remarkable variation near the heterointerface. Using STEM-EELS line scan, we observe an asymmetric cationic intermixing at the interface between STO and SMO. A simulation of STEM-EELS spectrum image was performed at the interface. This demonstrates that the beam-spreading effect is weak and confirms the intermixing data. The EELS fine structure of Mn-L2,3 edges unveils a variation of Mn oxidation states at the heterointerface.