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Article Dans Une Revue Journal of Physics: Condensed Matter Année : 2008

The role of strain-induced structural changes in the metal insulator transition in epitaxial SmNiO3 films

Résumé

The present work is devoted to explaining the role of epitaxial strain in the structure and the metal–insulator (MI) transition in SmNiO3 (SNO) films deposited on LaAlO3 (LAO) and SrTiO3 (STO) substrates. X-ray reciprocal space mapping and valence bond calculations allow us to show that in-plane compressive strain (for SNO/LAO) stabilizes Ni3+ in the orthorhombically distorted structure with the result that films exhibit a sharp MI transition at 120 ◦C, whereas in-plane tensile strain (for SNO/STO) stabilizes Ni2+, implying the creation of oxygen vacancies, which is accompanied by a ‘flattening' of the resistivity curves together with a huge increase of the overall resistivity. As SNO films are deposited on STO, we demonstrate that strain relaxation acts like the temperature or the rare-earth size, increasing the Ni–O–Ni bond angles. Hence in-plane tensile strain shifts the MI transition towards high temperatures. The flattening of the resistivity curve observed for SNO/STO can be understood by taking into account the inhomogeneous strain distribution across the film thickness (strain gradient) while the increase in resistivity has been ascribed to the homogeneous part of the strain.
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Dates et versions

hal-00266274 , version 1 (21-03-2008)

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Florine Conchon, Alexandre Boulle, René Guinebretière, Eric Dooryhee, Jean-Louis Hodeau, et al.. The role of strain-induced structural changes in the metal insulator transition in epitaxial SmNiO3 films. Journal of Physics: Condensed Matter, 2008, 20, pp.145216-1-145216-7. ⟨10.1088/0953-8984/20/14/145216⟩. ⟨hal-00266274⟩
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