Resonant x-ray scattering (RXS)

Resonant x-ray scattering (RXS) is a synchrotron-based technique that detects periodic modulations of electronic charge, orbital occupation, or spin in crystalline materials by measuring how x-rays scatter from a sample when their energy is tuned to a specific atomic absorption edge. Under this resonance condition, the scattering signal from valence electrons is dramatically enhanced, giving RXS extraordinary sensitivity to subtle electronic ordering phenomena that are often invisible to conventional x-ray diffraction. By scanning the momentum transferred to the sample, one can map directly in reciprocal space the wave vector, correlation length, and symmetry of the ordered state.

RXS has played a central role in establishing charge-density-wave order as a universal feature of the cuprate high-temperature superconductors and in characterizing its competition with superconductivity, and it continues to be extended through combination with ultrafast light sources and high magnetic fields to probe electronic order under extreme and nonequilibrium conditions.

In our work, RXS provides a powerful complement to photoemission, allowing us to connect momentum-resolved electronic structure to collective ordering phenomena in quantum materials.