Dispersion and energy scale of collective charge excitations in cuprates

Determine the dispersion relation and characteristic energy scale of the collective charge excitation mode in hole-doped cuprate superconductors near the charge-ordering wave vector by isolating its spectral weight from overlapping phonon contributions in oxygen K-edge resonant inelastic x-ray scattering measurements.

Background

Recent high-resolution RIXS studies on cuprates have revealed phonon anomalies and low-energy modes near the charge-ordering wave vector, suggesting the presence of charge density fluctuations. However, the weak charge signal overlaps with multiple phonon modes, making it experimentally challenging to extract the intrinsic charge-excitation spectral weight.

Because of this interference, essential information about the charge excitations—specifically their dispersion and energy scale—has not been directly resolved, limiting the ability to quantify interaction strengths and to connect charge dynamics to superconductivity and strange-metal behavior.