Immediately prior to the discovery of cuprate high-temperature superconductors (HTS) the American Physical Society was proposing to remove superconductivity as a specific topic in the Physical Review journals and the March meetings. The field had somewhat stagnated. That decision was vetoed by Neil Ashcroft from Cornell University who was at the time Chair of the Condensed Matter Section. Since then, starting with cuprates, there has been an ongoing explosion of new materials and discoveries, resulting finally in the achievement of room-temperature superconductivity in hydrides, predicted long ago by Ashcroft. At the same time, applications of cuprate HTS have also escalated rapidly including, for example, the development of prototype coils for fusion Tokamaks. Will the field stagnate again? It’s hard to imagine now. This talk will identify a number of continuing challenges for the field. Cuprate physics remains a puzzle in both the under- and over-doped regimes, and for different reasons. How can the already high-performing cuprates be further enhanced? And how can the huge pressures needed for room-temperature hydride superconductivity be circumvented? There is still much to be done and much to be gained.

Keywords: cuprates, hydrides, critical current, pressure