Resonant x-ray scattering in La1-xSr1+xMn0 4 (x 0.5): Incommensurate-lattice modulation vs. Charge-stripe models

Subías, G. (Universidad de Zaragoza) ; García, J. ; Herrero-Martín, J. ; Blasco, J. (Universidad de Zaragoza) ; Sánchez, M.C.

Resumen: Using resonant x-ray scattering at the Mn K-edge, we have investigated the nature of the charge and lattice modulation in the La1-xSr1+xMnO4 (x=0.5 and 0.6) manganites. Resonant reflections (h±e, h±e, 0) and (h±2e, h±2e, 0) of the tetragonal I4/mmm structure with a modulation vector of 2e=l-x were found in the insulating phases of both manganites but the intensity of these reflections is much weaker for La0.4Sr1.6MnO4. Resonant x-ray scattering data for the two samples are well explained by the presence of two types of sinusoidal modulations of the oxygen displacements, transverse and longitudinal to the tetragonal [110] direction. The amplitude of the oxygen displacements for any of the modulations decreases with the hole doping, in agreement with the change from a commensurate (x=0.5) to an incommensurate (x=0.6) ordered phase. The different polarization and azimuthal behaviour of the two sets of resonant reflections rule out any kind of stripe model composed by Mn3+-like and Mn4+-like charge-ordering. The maximum charge disproportionation among the different Mn atoms in the unit cell is about 0.15 e- and 0.04 e- for the x=0.5 and x=0.6 samples, respectively. These results thus confirm the existence of a charge-density-wave ordering in both the commensurate-phase of the half-doped La0.5Sr1.5MnO4 and the incommensurate-phase of the over-doped La0.4Sr1.6MnO4 manganites.

Idioma: Inglés

DOI: 10.1088/1742-6596/519/1/012008

Año: 2014

Publicado en: Journal of physics. Conference series 519, 1 (2014), 012008 [6 pp]
ISSN: 1742-6588

Tipo y forma: Artículo (Versión definitiva)

Área (Departamento): Física de la Materia Condensada (Departamento de Física de la Materia Condensada)