Superconducting nitrides: Versatile thin-film platforms for cryogenic technologies (Topical Review)

Forty years after the discovery of high-temperature superconductivity, this field continues to advance not only through the pursuit of ever-increasing critical temperatures but also due to the development of superconducting materials optimized for practical quantum and cryogenic technologies. This review examines the evolving role of superconducting nitrides as a technologically important class of materials complementing high-Tc superconductors by combining robust superconducting properties with chemical stability, mechanical hardness, and scalable thin-film fabrication. We summarize recent advances in both established and novel nitride superconductors, including NbN, NbTiN, TiN, MoN, VN, nitridized aluminum, and recently discovered unconventional chromium-based nitrides. The main attention is given to the comparative evolution from Nb to NbN and NbTiN as thin-film platforms for superconducting electronics and quantum photonics. While Nb remains a foundational material for classical Josephson electronics and accelerator technologies, two other nitride superconductors are increasingly finding applications at the forefront of multifunctional superconducting systems due to their higher critical temperatures, larger energy gaps, increased durability, and compatibility with nanoscale architectures. We argue that NbTiN, in particular, has the potential to become a unifying platform linking superconducting logic, quantum electronics and photonics.