Electronic and magnetic excitations in the "half-stuffed" Cu--O planes of Ba$_2$Cu$_3$O$_4$Cl$_2$ measured by resonant inelastic x-ray scattering

S. Fatale; C. G. Fatuzzo; P. Babkevich; N. E. Shaik; J. Pelliciari; X. Lu; D. E. McNally; T. Schmitt; A. Kikkawa; Y. Taguchi; Y. Tokura; B. Normand; H. M. Rønnow; M. Grioni

doi:10.1103/physrevb.96.115149

arXiv · 1709.03427

Electronic and magnetic excitations in the "half-stuffed" Cu--O planes of Ba$_2$Cu$_3$O$_4$Cl$_2$ measured by resonant inelastic x-ray scattering

S. Fatale·C. G. Fatuzzo·P. Babkevich·N. E. Shaik·J. Pelliciari·X. Lu·D. E. McNally·T. Schmitt·A. Kikkawa·Y. Taguchi·Y. Tokura·B. Normand·H. M. Rønnow·M. Grioni

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Abstract

We use resonant inelastic x-ray scattering (RIXS) at the Cu L$_3$ edge to measure the charge and spin excitations in the "half-stuffed" Cu--O planes of the cuprate antiferromagnet Ba$_2$Cu$_3$O$_4$Cl$_2$. The RIXS line shape reveals distinct contributions to the $dd$ excitations from the two structurally inequivalent Cu sites, which have different out-of-plane coordinations. The low-energy response exhibits magnetic excitations. We find a spin-wave branch whose dispersion follows the symmetry of a CuO$_2$ sublattice, similar to the case of the "fully-stuffed" planes of tetragonal CuO (T-CuO). Its bandwidth is closer to that of a typical cuprate material, such as Sr$_2$CuO$_2$Cl$_2$, than it is to that of T-CuO. We interpret this result as arising from the absence of the effective four-spin inter-sublattice interactions that act to reduce the bandwidth in T-CuO.

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S. Fatale, C. G. Fatuzzo, P. Babkevich, N. E. Shaik, J. Pelliciari, X. Lu, D. E. McNally, T. Schmitt, A. Kikkawa, Y. Taguchi, Y. Tokura, B. Normand, H. M. Rønnow, M. Grioni. 2017-09-11. Electronic and magnetic excitations in the "half-stuffed" Cu--O planes of Ba$_2$Cu$_3$O$_4$Cl$_2$ measured by resonant inelastic x-ray scattering. https://doi.org/10.1103/physrevb.96.115149

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