Monney, ClaudeBisogni, ValentinaZhou, Ke-JinKraus, RobertoStrocov, Vladimir N.Behr, GuenterMalek, JiriKuzian, RomanDrechsler, Stefan-LudwigJohnston, SteveRevcolevschi, AlexandreBuechner, BerndRonnow, Henrik M.Van Den Brink, JeroenGeck, JochenSchmitt, Thorsten2013-03-282013-03-282013-03-28201310.1103/PhysRevLett.110.087403https://infoscience.epfl.ch/handle/20.500.14299/90737WOS:000315141600030We 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 us to probe short-range spin correlations on the 1 meV scale with outstanding sensitivity. DOI: 10.1103/PhysRevLett.110.087403MPBHtext::journal::journal article::research article