One-Stage Hydrothermal Growth and Characterization of Epitaxial LaMnO Films on SrTiO Substrate.

Epitaxial LaMnO thin films were grown on SrTiO substrate using a one-stage hydrothermal route from La(NO), MnCl and KMnO in an aqueous solution of 10 M KOH at 340 °C. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) indicate full coverage of LaMnO on the substrate. X-ray diffraction in the symmetric ω/2θ mode suggests the film has an out-of-plane preferred orientation along the [001] direction of the substrate. The LaMnO epitaxial thin film growth mechanism is proposed based on the analysis of the atomic sharp interface formed between LaMnO and the SrTiO substrate, as seen by aberration-corrected scanning transmission electron microscopy (AC-STEM) imaging in combination with electronic energy loss spectroscopy (EELS). Compared with the conventional vapor deposition methods, the one-stage hydrothermal route opens up a new way to fabricate complex oxide epitaxial heterostructures.