LaAlO 3 stoichiometry is key to electron liquid formation at LaAlO 3/SrTiO 3 interfaces

M. P. Warusawithana, C. Richter, J. A. Mundy, P. Roy, J. Ludwig, S. Paetel, T. Heeg, A. A. Pawlicki, L. F. Kourkoutis, M. Zheng, M. Lee, B. Mulcahy, W. Zander, Y. Zhu, J. Schubert, J. N. Eckstein, D. A. Muller, C. Stephen Hellberg, J. Mannhart, D. G. Schlom

Research output: Contribution to journalArticle

Abstract

Emergent phenomena, including superconductivity and magnetism, found in the two-dimensional electron liquid (2-DEL) at the interface between the insulators lanthanum aluminate (LaAlO3) and strontium titanate (SrTiO 3) distinguish this rich system from conventional 2D electron gases at compound semiconductor interfaces. The origin of this 2-DEL, however, is highly debated, with focus on the role of defects in the SrTiO3, while the LaAlO3 has been assumed perfect. Here we demonstrate, through experiments and first-principle calculations, that the cation stoichiometry of the nominal LaAlO3 layer is key to 2-DEL formation: only Al-rich LaAlO3 results in a 2-DEL. Although extrinsic defects, including oxygen deficiency, are known to render LaAlO3/SrTiO 3 samples conducting, our results show that in the absence of such extrinsic defects an interface 2-DEL can form. Its origin is consistent with an intrinsic electronic reconstruction occurring to counteract a polarization catastrophe. This work provides insight for identifying other interfaces where emergent behaviours await discovery.

Original languageEnglish (US)
Article number2351
JournalNature communications
Volume4
DOIs
StatePublished - Sep 3 2013

ASJC Scopus subject areas

  • Chemistry(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Physics and Astronomy(all)

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    Warusawithana, M. P., Richter, C., Mundy, J. A., Roy, P., Ludwig, J., Paetel, S., Heeg, T., Pawlicki, A. A., Kourkoutis, L. F., Zheng, M., Lee, M., Mulcahy, B., Zander, W., Zhu, Y., Schubert, J., Eckstein, J. N., Muller, D. A., Hellberg, C. S., Mannhart, J., & Schlom, D. G. (2013). LaAlO 3 stoichiometry is key to electron liquid formation at LaAlO 3/SrTiO 3 interfaces. Nature communications, 4, [2351]. https://doi.org/10.1038/ncomms3351