Indirect RIXS as a direct probe for non-local correlations in Cuprate chains

Recent studies have suggested that one-dimensional cuprate chains and quasi-1D cuprate ladders have a sizeable nearest neighbor attractive interaction V,  which raises questions on the true minimal model for the high-Tc cuprate materials. Most of the evidence so far for an attractive V has come from combined theory-experiment studies of low-energy magnetic excitations or photoemission spectra. Here, we show that the charge excitation spectrum accessible through indirect RIXS at the Cu K-edge offers a clearer signature for V in doped chains. Our findings thus provide novel predictions for experimentally verifying the presence of V.