Soft X-ray resonant scattering study of single-crystal LaSr2Mn2O7

摘要

Soft X-ray resonant scattering studies at the Mn LII, III- and the La MIV, V- edges of singlecrystal LaSr2Mn2O7 are reported. At low temperatures, below TN ≈ 160 K, energy scans with a fixed momentum transfer at the A-type antiferromagnetic (0 0 1) reflection around the Mn LII, III-edges with incident linear σ and π polarizations show strong resonant enhancements. The splitting of the energy spectra around the Mn LII, III-edges may indicate the presence of a mixed valence state, e.g., Mn3+/Mn4+. The relative intensities of the resonance and the clear shoulder-feature as well as the strong incident σ and π polarization dependences strongly indicate its complex electronic origin. Unexpected enhancement of the charge Bragg (0 0 2) reflection at the La MIV, V-edges with σ polarization has been observed up to 300 K, with an anomaly appearing around the orbital-ordering transition temperature, TOO ≈ 220 K, suggesting a strong coupling (competition) between them.