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

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 $1\mathrm{eV}\le \mathrm{\Delta E}\le 15\mathrm{eV}$ has been measured in detail with the data analysis focusing on the energy loss region $1\mathrm{eV}\le \mathrm{\Delta E}\le 5\mathrm{eV}$, which includes a strong peak located at $\Delta E\approx 2\mathrm{eV}$. We observe a clear dispersion of up to $0.5\mathrm{eV}$ in the measured $\text{q}$ 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 $\text{q}=(h,h,0)$, $h=0.1-0.5$, 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.

References in corpus (3)

• Reentrant Orbital Order and the True Ground State of LaSr2Mn2O7
• Resonant inelastic x-ray scattering study of hole-doped manganites La1-xSrxMnO3 (x=0.2 and 0.4)
• Hard x-ray spectroscopy in NaxCoO2 and superconducting NaxCoO2 - yH2O: A view on the bulk Co electronic properties