High transition temperature superconductivity in the cuprates has remained one of the most intriguing and mysterious phenomena in condensed matter physics. Numerous experiments have suggested that the cuprates exhibit a pairing state that differs from conventional BCS theory. Furthermore, the appearance of an anisotropic gap in the electronic density of states above the critical temperature, dubbed the “pseudogap” phase, has led to countless speculations on the nature of strongly correlated electrons in these cuprates. Here, I will give a quick historical overview of high-temperature superconductivity. I will go over a few proposed candidates of the potential source of the pseudogap in the cuprates. Finally, I will discuss how angle-resolved photoemission spectroscopy (ARPES) experiments can further our understanding of the pseudogap phase.
