Doping and temperature dependence of Mn 3d states in A-site ordered manganites

TL;DR

This study investigates how doping and temperature affect the electronic structure of A-site ordered manganites, revealing complex interactions between orbital, charge, and magnetic states through combined experimental and theoretical analysis.

Contribution

It provides new insights into the doping and temperature dependence of Mn 3d states, highlighting the role of oxygen holes and magnetic correlations in these materials.

Findings

Spectral changes with doping are dominated by oxygen hole distribution.

Temperature effects are primarily due to increased magnetic correlations.

Neutron diffraction reveals structural changes correlating with electronic states.

Abstract

We present a systematic study of the electronic structure in A-site ordered manganites as function of doping and temperature. The energy dependencies observed with soft x-ray resonant diffraction (SXRD) at the Mn L_{2,3} edges are compared with structural investigations using neutron powder diffraction as well as with cluster calculations. The crystal structures obtained with neutron powder diffraction reflect the various orbital and charge ordered phases and show an increase of the Mn-O-Mn bond angle as function of doping and temperature. Cluster calculations show that the observed spectral changes in SXRD as a function of doping are more pronounced than expected from an increase in bandwitdh due to the increase in Mn-O-Mn bond angle, and are best described by holes that are distributed at the neighbouring oxygen ions. These holes are not directly added to the Mn 3d shell, but centered at the Mn site. In contrast, the spectral changes in SXRD as function of temperature are best described by an increase of magnetic correlations. This demonstrates the strong correlations between orbitals and magnetic moments of the 3d states.