A brief perspective of high temperature superconductivity in the cuprates: Strong correlations combined with superexchange match experiment

Abstract: High temperature superconductivity encompasses the cuprates, nickelates, iron pnictides, and LaH$<em>x$ compounds. The first three groups of compounds involve in the pairing electrons, which are strongly to moderately correlated, whereas in the last class of systems specific phonon excitations. In this overview we concentrate first on the (semi)quantitative theory of high T$</em>{C}$ superconductivity in the cuprates based on our original vibrational approach beyond the renormalized mean field theory. The model we explore mainly is $t$-$J$-$U$ model containing both the superexchange (kinetic energy) combined with strong interelectronic correlations. Selected equilibrium and dynamic-excitation properties are analyzed briefly. General questions regarding the pseudogap and two--dimensional character of those systems are raised.