We discuss three examples of emergent behavior in correlated electron matter, in which the discovery of scaling of several measured quantities with a single energy scale provides a key clue to a common magnetic origin: the emergence of itinerant (mobile) electronic behavior from the Kondo lattice of localized f electrons found in cerium- and uranium-based heavy fermion materials; the emergence of unconventional superconductivity in the cuprate and “high-temperature” heavy electron Ce- and Pu-based 1-1-5 superconductors; and the emergence of pseudogap behavior in the underdoped and optimally doped cuprate superconductors.We conclude with some speculation on ways in which these novel perspectives might be used to design new materials.

We developed a novel electron-diffraction technique by focusing a small probe above (or below) the sample in an electron microscope to measure charge density and lattice displacement in technologically important materials. The method features the simultaneous acquisition of shadow images within many Bragg reflections, resulting in parallel recording of dark-field images (PARODI). Because it couples diffraction with images, it is thus suitable for studying crystals as well as their defects. We used this technique to accurately locate the charge-carrying holes in superconducting crystals, and to determine displacement vectors across planar faults by comparing the experiments with calculations, and by using fitting and error analyses. Examples are given for complex YBa2Cu3O7 and Bi2Sr2CaCu2O8+δ oxides and the newly discovered MgB2 superconductor.