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arXiv · 1007.2283

d-d Excitations in Bilayer Manganites Probed by Resonant Inelastic X-ray Scattering

F. Weber·S. Rosenkranz·J. -P. Castellan·R. Osborn·J. F. Mitchell·H. Zheng·D. Casa·J. H. Kim·T. Gog
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Abstract

We report a high resolution resonant inelastic x-ray scattering investigation of the bilayer manganites La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ with $x = 0.36$ and $0.5$. The momentum dependence along the crystallographic $(110)$ direction for energy losses $1\,\rm{eV} \leq ΔE \leq 15\,\rm{eV}$ has been measured in detail with the data analysis focusing on the energy loss region $1\,\rm{eV} \leq ΔE \leq 5\,\rm{eV}$, which includes a strong peak located at $ΔE \approx 2\,\rm{eV}$. We observe a clear dispersion of up to $0.5\,\rm{eV}$ in the measured $\textbf{q}$ range, which is direct evidence of the non-local character of this excitation. Further, we found that the intensity in this low energy region strongly depends on both the reduced wave vector $\textbf{q} = (h, h, 0)$, $h = 0.1 - 0.5$, and temperature, i.e. different ordered phases. Results can be explained via an intersite $d-d$ charge transfer excitation, proposed for pseudo-cubic manganites, where the hopping rate is strongly increased (decreased) by ferromagnetic (antiferromagnetic) alignment of neighboring in-plane Mn ion core spins.

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F. Weber, S. Rosenkranz, J. -P. Castellan, R. Osborn, J. F. Mitchell, H. Zheng, D. Casa, J. H. Kim, T. Gog. 2010-07-14. d-d Excitations in Bilayer Manganites Probed by Resonant Inelastic X-ray Scattering. https://doi.org/10.1103/physrevb.82.085105

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