High-temperature superconductivity is perhaps one of the most compelling problems in contemporary physics. Despite their highly defective structures they exhibit a robust superconducting (SC) ground state. Worldwide efforts to understand their SC mechanism have been ongoing since their discovery in the mid-eighties. These research efforts are propelled by our natural proclivity to unravel inner-workings of the world around us on one hand and an unending hope of discovering a route to room-temperature superconductors on the other. The more we learn about these systems, however, the more elusive they appear. In conventional superconductors SC electrons appear uniform or homogeneous. One of the hallmarks of high-temperature superconductors is how different they are in this respect. Numerous experiments, such as electron microscopic studies, indicate that copper-oxide superconductors are electronically \"inhomogeneous\" even in their SC state. Although no general consensus of their origin exists, it is believed that an understanding of their microscopic nature may hold the key to unlock their mystery. This colloquium focuses on how x-ray scattering studies have shaped our understanding of inhomogeneous natures and of the role of intrinsic \"defects\" in electronic phase diagram of these superconductors. These studies have revealed an intrinsically modulated structure on a \"hierarchy\" of length scales rendering the material to be patchy and susceptible to Fermi-surface effects. Being intrinsic these modulations are inescapable and, in turn, inevitably influence all electronic properties of these compounds.
*Use of the Advanced Photon Source is supported by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357
Host: Stefan Kycia