Twisted Nodal Superconductors

Recent proposals for the realization of time-reversal symmetry breaking and topological superconductivity in twisted nodal superconductors (TNSs) have led to a surge of theoretical and experimental studies of these systems, marking one of the newest entries in the rapidly growing field of moiré materials. The interplay between order parameters of the separate layers makes TNSs unique, leading to additional emergent phenomena in regimes usually not of importance in moiré physics, such as bulk interfaces and large twist angles. We review the physics of TNSs, highlighting both similarities and qualitative differences with other moiré platforms. Although inspired by the rise of moiré materials, the field is anchored in studies of unconventional superconductivity preceding the moiré era, which we discuss in detail. In addition to summarizing the developments at the present stage, we present a detailed outlook on the major open questions in the field and some of the most exciting future directions.