Superconductors are materials in which electrical current flows with a resistance of zero, typically below specific temperatures. In conventional superconductors, this state of matter emerges when two electrons bind together at low temperatures, forming so-called Cooper pairs.

Yet some materials, referred to as unconventional superconductors, exhibit superconductivity under unusual conditions and cannot be explained by conventional theories. Understanding these unusual cases could lead to the development of superconductors that can operate at high enough temperatures to be used in real-world devices with less refrigeration.

Researchers at Harvard University and the University of Stuttgart theoretically demonstrated that an unusual form of graphene, known as valley-imbalanced rhombohedral tetralayer graphene, could host unconventional superconducting states.