Dependence of the Jahn-Teller distortion in LaMn 1-x ScxO3 on the isovalent Mn-site substitution

16th International Conference on X-ray Absorption Fine Structure

Subías, G.^1 ; Cuartero, V.^2 ; Blasco, J.^1 ; García, J.^1 ; Meneghini, C.^3 ; Aquilanti, G.^4

Instituto de Ciencia de Materiales de Aragón, Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, C/ Pedro Cerbuna 12, Zaragoza

50009, Spain^1

ESRF-The European Synchrotron, 71, Avenue des Martyrs, Grenoble, France^2

Dipartimento di Scienze, Università Roma TRE, Via della Vasca Navale 84, Rome

00146, Italy^3

Elettra-Sincrottrone Trieste, S.S. 14, Km 163.5, Trieste, Basovizza

34149, Italy^4

关键词: Ferromagnetic behaviors;    Local structure;    Mn site substitution;    Orthorhombic distortion;    Spin flipping;    Sub-lattices;    Substituted compounds;    Superexchanges;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/712/1/012119/pdf
DOI  :  10.1088/1742-6596/712/1/012119

来源: IOP

【 摘 要 】

We investigated the relative importance of removing the Mn3+Jahn-Teller distortion in driving ferromagnetism in LaMn1-xScxO3combining x-ray powder diffraction and x-ray absorption spectroscopy at the Mn and Sc K-edges. By increasing the Sc content, the orthorhombic distortion of the Pbnm cell in LaMnO3decreases but the unit-cell remains slightly distorted in LaScO3. Besides, the nearly tetragonal-distorted MO6in LaMnO3continuously evolves into a nearly regular one in LaScO3. On the other hand, x-ray absorption spectra show that the MnO6octahedron remains Jahn-Teller distorted and the ScO6octahedron is nearly regular along the whole series. Moreover, the ordering of the Mn3+Jahn-Teller distortion is not disrupted in the ab plane for any Sc concentration. This contrasts with the Ga- substituted compounds, where a regular MnO6is found for x>0.5. However, both LaMn0.5Sc0.5O3and LaMn0.5Ga0.5O3show ferromagnetic behavior independently of the presence (or not) of Jahn-Teller distorted Mn3+. Thus, our results point to the Mn-sublattice dilution as the main effect in driving ferromagnetism in these manganites over local structure effects previously proposed by the spin flipping or the vibronic superexchange models.