The Saga of Superconductivity: 100, 40, and 1 year later

"Free-flowing currents in superconductors have attracted the attention of scientists and the public since their discovery more than 100 years ago at 4K by Heike Kamerlingh Onnes. Nowadays, superconductivity is extremely relevant owing to the need for reducing our energy consumption and to find ways to generate clean energy using fusion reactors.

Achieving superconductivity at higher temperatures is fundamental to its technological application. Thus, the search for a room temperature superconductor is constant with claims of room temperature superconductivity every few years. The promise seemed to be materialized after the discovery of High Temperature superconductors (HTS) by K. Alexander Müller and J. Georg Bednorz almost 40 years, surpassing liquid nitrogen temperatures. Indeed, soon after we were inundated by predictions of a great future.

These predictions have failed (utterly) because of materials and thermodynamic reasons. Namely, the ceramic nature of these materials made it impossible to make wires directly and the high temperature of the transition temperature led to new superconducting phases that cannot carry supercurrents. Since then, we continually receive news (so far unfounded) of room temperature superconductivity or other great discoveries.

In this colloquium, I will discuss the importance of the different states of the matter and phase transitions, and how can we use this knowledge to determine if these new ‘superconductors’ are real. I will also show some important aspects of the history of superconductivity and key factors needed to make them useful for technological applications. In particular, work done at Los Alamos National Laboratory to improve the performance of HTS using the highest, non-destructive magnets available in the world. To finalize, I will highlight what a truly ‘useful’ superconductor looks like, and why the search for room temperature superconductivity might not be the way to go."