Surfaces, Interfaces and Films

Evidence of strain induced structural change in hetero-epitaxial NdNiO₃ thin films with metal-insulator transition

P. Laffez^a1, O. I. Lebedev^a2, P. Ruello^a1, R. Desfeux^a3, G. Banerjee^a4 and F. Capon^a1

Laboratoire de Physique de l'État Condensé, UMR CNRS 6087, Université du Maine, avenue O. Messiaen, 72085 Le Mans Cedex, France

EMAT, University of Antwerp, Groeonenborgerlaan 171, 2020 Antwerp, Belgium

Laboratoire de Physico-Chimie des Interfaces et Applications, Université d'Artois, rue Jean Souvraz, SP 18, 62307 Lens Cedex, France

Exp. Cond. Matter Physics Division, Saha Institute of Nuclear Physics 1/AF Bidhan Nagar, Calcutta 700064, India

Abstract

Neodymium nickelate thin films have been prepared on NdGaO₃ substrates by RF magnetron sputtering and post-annealing treatment under oxygen pressure. Transport properties are found to depend strongly on film thickness. Thick films show transport properties close to bulk ceramics, while very thin films exhibit a large transition from metal to insulator which occurs over a wide temperature range with high resistivity. Structure and surface morphology of the films have been investigated by Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM). Thin films (≈17 nm) grow heteroepitaxially, while thicker films (≈73 nm) show a granular structure. The thinnest sample suggests a symmetry change induced by the epitaxial strain of the substrate. This paper discusses the relationship between microstructure and transport properties.

(Received January 13 2003)

(Revised October 14 2003)

(Accepted October 17 2003)

(Online publication December 2 2003)

PACS:

• 73.50.-h – Electronic transport phenomena in thin films;
• 71.30.+h – Metal-insulator transitions and other electronic transitions;
• 73.61.-r – Electrical properties of specific thin films

patrick.laffez@univ-lemans.fr