Separating the causes of orbital ordering in LaSr2Mn2O7 using resonant soft x-ray diffraction

Resonant soft x-ray diffraction has been used to probe the temperature dependent orbital and magnetic structure of LaSr2Mn2O7. Previous crystallographic studies have shown that this material has almost no MnO6 oxygen displacements due to Jahn-Teller distortions at low temperatures. Within the low-temperature A-type antiferromagnetic phase, we found strong intensity at the (&frac {1}{4},frac {1}{4},0;) orbital and (,0, 1) magnetic reflections. This shows that even in the near absence of Jahn-Teller distortions, this compound is strongly orbitally ordered. A fit to the Mn L-edge resonance spectra demonstrates the presence of orbital ordering of the Mn3+ ions with virtually no Jahn-Teller crystal field in addition to possible Mn3+ and Mn2+-like valence fluctuations.