Probing the spin polaron excitations in electron-doped cuprates

A recent breakthrough in the understanding of charge dynamics in cuprates is the discovery and characterization of the three-dimensional plasmon in electron-doped superconductors. This, however, represents only one of the two types of collective charge modes in the cuprates. As well as the three- dimensional plasmon, t-J model calculations also predict the presence of a spin polaron excitation, which is a lower energy mode that arises from the formation of a narrow polaronlike band of spin correlation dressed bosons. This proposal will use Cu L-edge resonant inelastic x-ray scattering (RIXS) measurements of La2-xCexCuO4 (LCCO) to discover the spin polaron excitation and characterize its momentum and doping dependence. The properties of this mode will provide critical information about the unconventional electron liquid that hosts high-temperature superconductivity, how it interacts with spin correlations and deepen our understanding of the t-J model and its validity.