Determining the nature of the high energy quasi-circular dynamic correlations in cuprates with polarimetric RIXS

Dynamic fluctuations from periodic charge order correlations pervade the phase diagram of cuprate superconductors, perhaps more so than superconductivity. Recent advances in the energy resolution of resonant inelastic x-ray scattering (RIXS) instruments operating in soft x-ray regime enabled the detection of these fluctuations over energy and momentum. We recently performed two Cu-L3 RIXS studies on Bi2Sr2CaCu2O8+x (Bi2212) [2-3] and discovered dynamic fluctuations peaking at |q|=qCO along ALL in-plane directions in double layer Bi2212 – a ring-like pattern with finite energy-loss and radius equal to charge order wave vector magnitude. These correlations connect to the static charge order in the cuprates given the |q|=qCO relation. However, the charge-like nature of these dynamic correlations has not yet been experimentally determined. We propose using polarimetric RIXS to identify whether the high-energy quasi-circular dynamic correlations in Bi2212 are charge or spin in nature.