https://www.sciencedaily.com/releases/2019/11/191121151209.htm > Both are rule-breakers. Strange metals don't behave like regular metals, whose electrons act independently; instead their electrons behave in some unusual collective manner. For their part, high-temperature superconductors operate at much higher temperatures than conventional superconductors; how they do this is still unknown. > In many high-temperature superconductors, changing the temperature or the number of free-flowing electrons in the material can flip it from a superconducting state to a strange metal state or vice versa.