Superconductivity at 100-Where we've been and where we're going

Basic scientific questions and tantalizingly revolutionary applications have been intertwined throughout the 100-year history of superconductivity. Within two years of his discovery of superconductivity in 1911, H. Kamerlingh Onnes imagined high-field applications for superconducting wires, only to have his hopes dashed by limitations of upper critical field and critical current density. Over the next 98 years, a scientific tango would play out repeatedly between (1) discovering and understanding new superconductors, often with higher transition temperature values and (2) improving these materials' upper critical field and critical current values while keeping manufacturing costs down. In this article, we take stock of where the field currently stands, with mature, developing, and recently discovered superconductors, and try to give a sense of where it may be going.