Atomic-Scale Visualization of the Cuprate Pair Density Wave State

A recent discovery of the pair density wave (PDW) order creates a stir in understanding an underlying physics in the pseudogap states of the cuprate high temperature superconductors. Recent Spectroscopic Imaging Scanning Tunneling Microscopy (SI-STM) measurements on Bi2Sr2CaCu2O8+delta identified that spatially uniform d-wave superconductivity (DSC), d-symmetry charge density wave (CDW), and the PDW play important roles in an intertwined fashion. In this review, we discuss how these different electronic degrees of freedom emerges in electronic structures of the cuprate and discuss how they are related to each other.