Separating the causes of orbital ordering in LaSr₂Mn ₂O₇ using resonant soft x-ray diffraction

Resonant soft x-ray diffraction has been used to probe the temperature dependent orbital and magnetic structure of LaSr₂Mn₂O ₇. 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 () orbital and (0, 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.