Determining the Short-Range Spin Correlations in Cuprate Chain Materials   with Resonant Inelastic X-ray Scattering
  We report a high-resolution resonant inelastic soft x-ray scattering study of the quantum magnetic spin-chain materials Li2CuO2 and CuGeO3. By tuning the incoming photon energy to the oxygen K-edge, a strong excitation around 3.5 eV energy loss is clearly resolved for both materials. Comparing the experimental data to many-body calculations, we identify this excitation as a Zhang-Rice singlet exciton on neighboring CuO4-plaquettes. We demonstrate that the strong temperature dependence of the inelastic scattering related to this high-energy exciton enables to probe short-range spin correlations on the 1 meV scale with outstanding sensitivity. 
Claude Monney, Valentina Bisogni, Ke Jin Zhou, Roberto Kraus, Vladimir   N. Strocov, Gunter Behr, Jiri Malek, Roman Kuzian, ...
cond-mat.str-el