Spectroscopy of orbital ordering in La0.5Sr1.5MnO4 : A many-body cluster calculation

TL;DR

This study models the orbital ordering in La0.5Sr1.5MnO4 using a many-body cluster approach, linking spectroscopic signatures to temperature-dependent distortions and spin correlations.

Contribution

It introduces a detailed cluster model incorporating electron correlation and charge transfer to analyze orbital ordering and its spectroscopic signatures.

Findings

Good agreement between model and experimental spectra.

Orbital ordering varies with oxygen distortion and spin correlation.

Spectroscopic features distinguish temperature effects.

Abstract

We have studied the orbital ordering (OO) in La0.5Sr1.5MnO4 and its soft x-ray resonant diffraction spectroscopic signature at the Mn L2, L3 edges. We have modelled the system in second quantization as a small planar cluster consisting of a central Mn atom, with the first neighbouring shells of oxygen and Mn atoms. For the effective Hamiltonian we consider Slater-Koster parameters, charge transfer and electron correlation energies obtained from previous measurements on manganites. We calculate the OO as a function of oxygen distortion and spin correlation used as adjustable parameters. Their contribution as a function of temperature is clearly distinguished with a good spectroscopic agreement.