Atomic-resolved depth profile of strain and cation intermixing around LaAlO 3 /SrTiO 3 interfaces

Hicham Zaid (1) , Marie-Hélène Berger (1) , Denis Jalabert (2) , M Walls (3) , R Akrobetu (4) , I Fongkaew (5) , W.R.L. Lambrecht (5) , N.J. Goble (5) , X.P.A. Gao (5) , P Berger (6) , Alp Sehirlioglu (4)

1 CDM - Centre des Matériaux
2 LEMMA - Laboratoire d'Etude des Matériaux par Microscopie Avancée
3 LPS - Laboratoire de Physique des Solides
4 Case Western Reserve University [Cleveland]
5 department of physics
6 LEEL - UMR 3685 - Laboratoire d'Etudes des Eléments Légers

Novel behavior has been observed at the interface of LaAlO 3 /SrTiO 3 heterostructures such as two dimensional metallic conductivity, magnetic scattering and superconductivity. However, both the origins and quantification of such behavior have been complicated due to an interplay of mechanical, chemical and electronic factors. Here chemical and strain profiles near the interface of LaAlO 3 /SrTiO 3 heterostructures are correlated. Conductive and insulating samples have been processed, with thicknesses respectively above and below the commonly admitted conductivity threshold. The intermixing and structural distortions within the crystal lattice have been quantitatively measured near the interface with a depth resolution of unit cell size. A strong link between intermixing and structural distortions at such interfaces is highlighted: intermixing was more pronounced in the hetero-couple with conductive interface, whereas in-plane compressive strains extended deeper within the substrate of the hetero-couple with the insulating interface. This allows a better understanding of the interface local mechanisms leading to the conductivity.

Domaines: Matériaux

Hicham Zaid, Marie-Hélène Berger, Denis Jalabert, M Walls, R Akrobetu, et al.. Atomic-resolved depth profile of strain and cation intermixing around LaAlO 3 /SrTiO 3 interfaces. Scientific Reports, 2016, 6, 28118, 13 p. ⟨10.1038/srep28118⟩. ⟨cea-01336337⟩