Seminarium Fizyki Materii Skondensowanej

Layered copper oxides are prototypical strongly correlated electron systems, evolving with chemical doping from the antiferromagnetic Mott insulating state, through the high-temperature superconducting phase, to the correlated metallic regime. Thanks to developments in spectroscopic techniques, a fairly complete mapping of quantum spin and charge fluctuations across the phase diagram has now become available for several cuprate families, which provides a testing ground for present theoretical models of those materials. I will summarize our recent theoretical study of collective spin (paramagnon) and charge (plasmon) excitations in the correlated metallic state of copper oxides.We find that paramagnon excitations persist down to the hole-overdoped regime and are less coherent on the electron-doped side of the phase diagram, in agreement with experiment. The role of strong electronic correlations and the underlying fermiology in stabilizing the magnetic excitations will be discussed. Finally, I will mention possible extensions to other classes of strongly correlated condensed-matter systems.