Eur. Phys. J. B 74, 457-461 (2010)
https://doi.org/10.1140/epjb/e2010-00117-3

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

¹ Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
² Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa, 50011, USA
³ Institut Laue-Langevin, BP 156, 38042 Grenoble Cedex 9, France
⁴ Institut für Experimentalphysik/Festkörperphysik, Ruhr-Universität Bochum, 44780 Bochum, Germany

Corresponding author: h.f.li@hotmail.com

Received: 3 November 2009
Revised: 22 February 2010
Published online: 7 April 2010

Abstract

Soft X-ray resonant scattering studies at the Mn L_{II, III}- and the La M_{IV, V}- edges of single-crystal LaSr₂Mn₂O₇ are reported. At low temperatures, below T_N ≈ 160 K, energy scans with a fixed momentum transfer at the A-type antiferromagnetic (0 0 1) reflection around the Mn L_{II, III}-edges with incident linear σ and π polarizations show strong resonant enhancements. The splitting of the energy spectra around the Mn L_{II, 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 M_{IV, V}-edges with σ polarization has been observed up to 300 K, with an anomaly appearing around the orbital-ordering transition temperature, T_OO ≈ 220 K, suggesting a strong coupling (competition) between them.