Plasmon excitations in the bilayer cuprate YBa2 Cu3 O7-δ

The dielectric properties of a system of 2D conducting sheets has a number of unique consequences for its plasmons, high-energy fluctuations of mobile charges from their electrostatic equilibrium.  Doped superconducting cuprates appear to meet all these requirements and plasmons with a strong linear dispersion down to low in-plane q have been extensively measured in single-layered systems using RIXS, this feature being characteristic of low-dimensional systems.  However, comparable studies in multi-layered cuprates are still lacking. During this seminar, I will present our findings on plasmons in the bilayer cuprate YBa₂Cu₃O_{7- δ} which have been based on RIXS measurements collected at the oxygen-K edge alongside an RPA model which is in good agreement with the data.