Suppression of the critical thickness threshold for conductivity at the LaAlO3/SrTiO3 interface

Perovskite materials engineered in epitaxial heterostructures have been intensely investigated during the last decade. The interface formed by an LaAlO 3 thin film grown on top of a TiO 2 -terminated SrTiO 3 substrate hosts a two-dimensional electronic system and has become the prototypical example...

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Bibliographic Details
Published in:Nature communications 2014-07, Vol.5 (1), p.4291-4291, Article 4291
Main Authors: Lesne, E., Reyren, N., Doennig, D., Mattana, R., Jaffrès, H., Cros, V., Petroff, F., Choueikani, F., Ohresser, P., Pentcheva, R., Barthélémy, A., Bibes, M.
Format: Article
Language:English
Subjects:
639/301/119/544
639/301/119/995
Cobalt
Condensed Matter
Electrons
Humanities and Social Sciences
multidisciplinary
Physics
Science
Science (multidisciplinary)
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Summary:Perovskite materials engineered in epitaxial heterostructures have been intensely investigated during the last decade. The interface formed by an LaAlO 3 thin film grown on top of a TiO 2 -terminated SrTiO 3 substrate hosts a two-dimensional electronic system and has become the prototypical example of this field. Although controversy exists regarding some of its physical properties and their precise origin, it is universally found that conductivity only appears beyond an LaAlO 3 thickness threshold of four unit cells. Here, we experimentally demonstrate that this critical thickness can be reduced to just one unit cell when a metallic film of cobalt is deposited on top of LaAlO 3 . First-principles calculations indicate that Co modifies the electrostatic boundary conditions and induces a charge transfer towards the Ti 3 d bands, supporting the electrostatic origin of the electronic system at the LaAlO 3 /SrTiO 3 interface. Our results expand the interest of this low-dimensional oxide system from in-plane to perpendicular transport and to the exploration of elastic and inelastic tunnel-type transport of (spin-polarized) carriers. The thin highly conducting electron layer at the interface of LaAlO 3 grown on SrTiO 3 is of promise for nanoscale electronics. Here, the authors show that, by depositing a thin cobalt film on top of LaAlO 3 , the minimum thickness of LaAlO 3 needed for this conducting layer to form can be reduced to one unit cell.
ISSN:2041-1723
2041-1723
DOI:10.1038/ncomms5291