Quantifying octahedral rotations in strained perovskite oxide films

Abstract

Epitaxial strain is a proven route to enhancing the properties of complex oxides, however, the details of how the atomic structure accommodates strain are poorly understood due to the difficulty of measuring the oxygen positions in thin films. We present a general methodology for determining the atomic structure of strained oxide films via x-ray diffraction, which we demonstrate using LaNiO3 films. The oxygen octahedral rotations and distortions have been quantified by comparing the intensities of half-order Bragg peaks, arising from the two unit cell periodicity of the octahedral rotations, with the calculated structure factor. Combining ab initio density functional calculations with these experimental results, we determine systematically how strain modifies the atomic structure of this functional oxide.Comment: 23 pages, 11 figure

Strain-driven spin-state transition and superexchange interaction in LaCoO3:Abinitiostudy

“…2). Since the LS CoO 6 unit is rigid due to covalency of the Co-O bond (bond stretching costs a large amount of energy), strain is mainly accommodated by tilting and rotation of CoO 6 octahedra [47]. Microscopically, this is achieved by changes in the Co-O-Co angles (θ in and θ out in Fig.…”

Elastic properties of rhombohedral, cubic, and monoclinic phases of LaNiO 3 by first principles calculations

“…On one hand, it implies that transformation of rhombohedral LaNiO 3 into monoclinically distorted structure induced by compressive or tensile strains does not have a strong influence on its mechanical behaviour. But on the other hand, one should take into consideration that here we are dealing with a fully relaxed monoclinic system which is slightly different from non-relaxed ones experimentally identified on SrTiO 3 and LaAlO 3 substrates [17]. However, we believe that our elastic parameters pretty reliably describe monoclinic LaNiO 3 as long as the thickness of the film is sufficiently large to prevent from the occurrence of metal-to-insulator transition.…”

“…221) [16] together with monoclinic (C2/c, No. 15) [17] structure that is available under tensile or compressive strains induced by various substrates. We hope that the obtained data will be helpful for many practical applications related to the mechanical behaviour of bulk LaNiO 3 , thin films, and heterostructures.…”

Electronic structure and orbital polarization of LaNiO3with a reduced coordination and under strain: A first-principles study

“…Strain affects most strongly the orbital character of the nickelates 15,[17][18][19][20] . Recently, several papers have focused on how changes in orbital polarization in heterostructures and thin films affect the electronic structure and thereby the macroscopic material properties 15,[17][18][19][20][21][22] .…”