Unravelling the ‘strange metal puzzle’ through the study of charge density fluctuations in overdoped cuprates

The strange metal phase, one of the grand challenges of strongly correlated systems, generally occurs close to a quantum critical point (QCP). This picture is also accepted in HTS: a QCP is postulated at p*, where the pseudogap ends at T→0. This scenario is overturned by recent experiments, hinting at a subordinal role of pseudogap. This either implies the absence of a QCP, or the presence of a QCP having different origin. To unravel this puzzle, we propose to study with RIXS charge density fluctuations (CDF), which permeate the strange metal at pp* and, if so, their doping dependence. The results will tell us if the HTS physics is connected to a quantum critical scenario, and if CDF are the quantum fluctuations related to the QCP.