The Onset of Phase Separation in the Double Perovskite Oxide La${}_2$MnNiO${}_6$

Abstract

Identification of kinetic and thermodynamic factors that control crystal nucleation and growth represents a central challenge in materials synthesis. Here we report that apparently defect-free growth of La${}_2$MnNiO${}_6$ (LMNO) thin films supported on SrTiO${}_3$ (STO) proceeds up to $1-5$ nm, after which it is disrupted by precipitation of NiO phases. Local geometric phase analysis and ensemble-averaged X-ray reciprocal space mapping show no change in the film strain away from the interface, indicating that mechanisms other than strain relaxation induce the formation of the NiO phases. $Abinitio$ simulations suggest that oxygen vacancies become more likely with increasing thickness, due to the electrostatic potential build-up associated with the polarity mismatch at the film-substrate interface, this, in turn, promotes the formation of Ni-rich regions. These results suggest that the precipitate-free region could be extended further by increasing the oxygen chemical potential through the use of an elevated oxygen pressure or by incorporating electron redistributing dopants to suppress the built-in potential.

arXiv comment17 pages, 4 figures

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• Ferromagnetism in semiconductors and oxides: prospects from a ten years' perspective
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Cited by in corpus (3)

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• Interfacial reconstruction effects in insulating double perovskite Nd${}_2$NiMnO${}_6$/SrTiO${}_3$ and Nd${}_2$NiMnO${}_6$/NdGaO${}_3$ thin films
• Site-selective polar compensation of Mott electrons in a double perovskite heterointerface