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arXiv · 1412.3422

Large electropositive cations as surfactants for the growth of polar epitaxial films

Alfred K. C. Cheung·Ilya Elfimov·Mona Berciu·George A. Sawatzky
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Abstract

Using density functional theory (DFT) we demonstrate that the adsorption of large cations such as potassium or cesium facilitates the epitaxial growth of polar LaAlO$_3$ (LAO) on SrTiO$_3$ (STO). The low ionization potential of K favors efficient electron transfer to the STO conduction band and results in a 2D electron gas which exactly compensates for the diverging potential with increasing layer thickness. For large cations like K or Cs, DFT total energy considerations show that they remain adsorbed on the LAO surface and do not enter substitutionally into LAO. These results suggest a novel scheme for growing clean LAO/STO interface systems, and polar systems in general, by performing the growth process in the presence of large, low ionization potential alkali metal ions.

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Alfred K. C. Cheung, Ilya Elfimov, Mona Berciu, George A. Sawatzky. 2014-12-10. Large electropositive cations as surfactants for the growth of polar epitaxial films. https://doi.org/10.1103/physrevb.91.125405

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