A Resonant soft x-ray powder diffraction study to determine the orbital ordering in A-site ordered SmBaMn2O6

TL;DR

This study uses soft X-ray resonant powder diffraction to identify orbital ordering in SmBaMn2O6, revealing an orbital reorientation transition at 210 K and associated changes in magnetic and charge properties.

Contribution

It provides direct experimental evidence of orbital ordering and reorientation in SmBaMn2O6 using resonant diffraction techniques, contrasting with previous indirect methods.

Findings

Orbital ordering of (x2-z2)/(y2-z2) type confirmed.

Orbital reorientation transition occurs at 210 K.

Charge localization increases below 210 K.

Abstract

Soft X-ray resonant powder diffraction has been performed at the Mn L2,3 edges of A-site ordered SmBaMn2O6. The energy and polarization dependence of the (1/2 1/2 0) reflection provide direct evidence for a (x2-z2)/(y2-z2) type orbital ordering in contrast to the single layer manganite. The temperature dependence of the reflection indicates an orbital reorientation transition at 210 K, below which the charge and orbital ordered MnO2 sheets show AAAA type of stacking. The concurring reduction of the ferromagnetic super exchange correlations leads to further charge localization.