Mn K edge resonant X-ray scattering of half-doped manganites
1 Institut de Ciència de Materials de Barcelona-CSIC, Campus Universitari de Bellaterra, 08193 Bellaterra, Spain
2 Instituto de Ciencia de Materiales de Aragón, Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009 Zaragoza, Spain
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Revised: 23 March 2012
Published online: 15 June 2012
We here revisit the concepts of the so-called charge and orbital order in half-doped manganites through the analysis of recent resonant X-ray scattering experiments at the Mn K edge on three different systems: Nd0.5Sr0.5MnO3, Bi0.5Sr0.5MnO3 and La0.5Sr1.5MnO4. By means of a semiempirical method and ab initio multiple scattering calculations we conclude that the description of the charge-localized phases is consistent with a model where two Mn atoms are occupying different crystallographic sites (Mn1, Mn2) displaying an electronic occupation that is mainly determined by the structural distortions. Regarding the local structure of these Mn sites, these distortions produce little variations on the charge density associated to the different crystallographic sites. Accordingly, the resulting bimodal distribution of charges is in all cases far from the theoretical arrangement of integer valence states.
© EDP Sciences, Springer-Verlag, 2012