In cuprates, as doping $p$ is reduced from the overdoped side through the quantum critical point $p^*$, a transition in Hall number density of carriers is observed, in which this number of carriers reduces from $1+p$ holes per copper site to $p$ holes per copper site. The connection of this $1+p$ to $p$ transition with pseudogap and with superconductivity is discussed. A "panoramic" view or a "broad-brush" discussion is presented in which Anderson's "unhappy" electrons take on a central stage.
Categories: cond-mat.supr-con cond-mat.str-el