Chemical bonding and electronic structure at hetero-interfaces: the case of perovskite oxides

Jean-Luc Maurice 1Cécile Carretero 1Karim Bouzehouane 1Marie-José Casanove 2Sabrina Guyard 1Jean-Pierre Contour 1Christian Colliex 3

1. Unité Mixte de Physique CNRS/Thales associée à l'Université Paris-Sud, Domaine de Corbeville, Orsay 91404, France
2. CEMES CNRS, BP 4347, Toulouse 31055, France
3. Laboratoire de Physique des Solides Université Paris-Sud (CNRS UMR8502), Orsay 91405, France

Abstract

The generic perovskite unit cell is a simple cube of formula ABO3 where A and B are respectively a large and a small cation. Depending on the nature of cations, the substitutions on either cationic site, and the amount and possible order of oxygen vacancies, perovskite oxides span an extremely wide range of solid state electronic and magnetic properties. Associating them by epitaxy creates a large field of research towards applications in the microelectronics area, in a context where silicon-based technology faces major challenges.

In <100> directions, perovskites are stacks of {200} planes of alternate compositions AO and BO2; there are thus two possibilities of stacking sequence at a {100} interface. Depending on the valency of the different cations in presence, these two may have dramatically different properties: at the interface between the insulators LaAlO3 and SrTiO3 for instance, high-mobility carriers were detected in the case of the -LaO-TiO2- sequence while the sequence -AlO2-SrO- was found insulating [1].

In order to reproduce the metallic -LaO-TiO2- interface, we have grown LaAlO3 onto TiO2-terminated (001) SrTiO3 using pulsed laser deposition; the samples obtained were conducting indeed. We have then observed this interface at the atomic level by aberration-corrected high-resolution transmission electron microscopy and electron energy loss spectroscopy. On the basis of our experimental observations, we discuss in this communication the origin of the measured electronic properties.

[1] A. Ohtomo and H. Y. Hwang, Nature 427, 423 (2004)

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Presentation: invited oral at E-MRS Fall Meeting 2005, Symposium F, by Jean-Luc Maurice
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-13 12:37
Revised:   2009-06-07 00:44
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