Eur. Phys. J. B 53, 23-28 (2006)
https://doi.org/10.1140/epjb/e2006-00340-5

Spectroscopy of La_0.5Sr_1.5MnO₄ orbital ordering: a cluster many-body calculation

¹ European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex, France
² Diamond Light Source, Chilton, Didcot, OX11 0DE, UK
³ CCLRC Daresbury Laboratory, Warrington, WA4 4AD, UK

Corresponding author: ^a mirone@esrf.fr

Received: 24 February 2006
Revised: 19 July 2006
Published online: 6 September 2006

Abstract

Orbital ordering (OO) in La_0.5Sr_1.5MnO₄ has been studied using soft X-ray resonant diffraction (SXRD) at the Mn L_2,3 edges in combination with many-body cluster calculations. The SXRD intensity is modelled in second quantization using a small planar cluster consisting of a central active Mn site with first-neighbour shells comprising O and Mn sites. The effective Hamiltonian includes Slater-Koster parameters and charge transfer and electron correlation energies obtained from previous measurements on manganites. The energy dependence of the SXRD OO peak is calculated using the Jahn-Teller distortions of the oxygen octahedra and in-plane spin correlations as adjustable parameters. These contributions are clearly distinguished above the Néel temperature with a good spectroscopic agreement. The results also suggest a significant charge separation between the Mn sites.