Local tetragonal distortion inLa0.7Sr0.3MnO3straine

Abstract

We report on an angular resolved X-ray Absorption Spectroscopy study of La 0.7 Sr 0.3 MnO 3 thin films epitaxially grown by pulsed laser deposition on slightly mismatched substrates which induce tensile or compressive strains. XANES spectra give evidence of tetragonal distortion within the MnO 6 octahedra, with opposite directions for tensile and compressive strains. Quantitative analysis has been done and a model of tetragonal distortion reflecting the strain has been established. EXAFS data collected in plane for tensile substrate confirm the change in the Mn − O average bond distance and the increase of Mn − Mn length matching with the enlargement of the cell parameter. From these results we conclude that there is no significant change in the Mn − O − Mn angle. Our observations conflict with the scenarios which this angle is the main driving parameter in the sensitivity of manganite films properties to external strains and suggest that the distortion within the octahedra plays a key role in the modification of the transport and magnetic properties.

Local atomic and electronic structures of epitaxial strained LaCoO3thin films

“…[20][21][22][23] In addition to affecting the spin state as discussed above, distortion and rotation of oxygen octahedra can alter magnetic properties by changing the magnetic exchange energy, which increases with additional overlap between Co(3d) derived e g and O(2p) orbitals, W . In this way, strain induced changes in Co-O hybridization can modify the magnetic properties of ferromagnetic perovskite oxides.…”

“…In this way, strain induced changes in Co-O hybridization can modify the magnetic properties of ferromagnetic perovskite oxides. 20,23 Increased Co-O hybridization has also been posited as a requirement for ferromagnetic ordering in LCO. 6 In order to provide insight into the nature of ferromagnetism in epitaxial LCO, we have undertaken a detailed investigation of the local and electronic structures of LCO thin films.…”

Stability of Ni sites across the pressure-induced insulator-to-metal transition in YNiO3

“…This increased overlap is less significant for localized 1s levels than for 4p delocalized ones and, consequently, the absorption edge shifts towards higher energies. For small shifts the bond length reduction (δR) and the associated edge shift (δE) are almost linearly related 24,25 . However, due to the mixture of close Ni bonds such linear relationship does not strictly apply in Y N iO 3 , and the evolution of the edge yields only a qualitative analysis.…”

Ab initioelectronic and magnetic structure in La0.66Sr0.33MnO3: strain and correlation effects

“…Effects induced by this approximation are quantitatively hard to predict; moreover, experiments suggest the tilting angle not to be strongly affected by different strain conditions. [26] The inplane lattice constants a are chosen according to the LAO, NGO, LSAT and STO bulk experimental values [6]; this is of course an approximation, and the theoretical substrate lattice constants might be used, as well. In some cases (i.e.…”