Magnetism and superconductivity at LAO/STO-interfaces: the role of Ti 3d interface electrons

ORAL

Abstract

Ferromagnetism and superconductivity are in most cases adverse. However, recent experiments reveal that they coexist at interfaces of LaAlO$_{3}$ and SrTiO$_{3}$ [1]. We analyze the ferromagnetic state within density functional theory and provide evidence that it is also generated by Ti 3d interface electrons, as is the two-dimensional electron liquid at the interface which gives rise to superconductivity [2]. We demonstrate that oxygen vacancies in the TiO$_{2}$ interface layer enhance the tendency for ferromagnetism considerably. This allows for the notion that areas with increased density of oxygen vacancies produce ferromagnetic puddles and account for the previous observation of a superparamagnetic behavior in the superconducting state [3].\\[4pt] [1] Lu Li, C.Richter, J.Mannhart, and R.C.Ashoori, Nature Physics 7, 762 (2011).\\[0pt] [2] N. Reyren et al., Science 317, 1196 (2007).\\[0pt] [3] N.Pavlenko, T.Kopp, E.Y.Tsymbal, G.A.Sawatzky, and J.Mannhart, cond-mat/arXiv:1105.1163 (2011)

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Authors

  • Natalia Pavlenko

    Institute of Physics, University of Augsburg (Germany); Institute for Condensed Matter Physics, Lviv (Ukraine)

  • Thilo Kopp

    University of Augsburg, Germany, Institute of Physics, University of Augsburg (Germany)

  • Evgeny Tsymbal

    University of Nebraska, Lincoln, Department of Physics and Astronomy, University of Nebraska-Lincoln, University of Nebraska - Lincoln, Department of Physics and Astronomy,University of Nebraska-Lincoln

  • George A. Sawatzky

    Department of Physics and Astronomy, University of British Columbia, Vancouver, Department of Physics and Astronomy, University of British Columbia, Canada

  • Jochen Mannhart

    Max Planck Institute for Solid State Research, Max Planck Institute for Solid State Research, Stuttgart (Germany)