Beyond BCS: Pairing Mechanisms, Material Families and the Contested Path to Ambient-Condition Superconductivity

Superconductivity research has moved through an unusually crowded stretch over the last five to sevenyears, and that pace has forced a reconsideration of how tightly the field should still be tied to the BardeenCooper-Schrieffer (BCS) picture of phonon-mediated pairing. Nickelates - first realised as infinite-layerthin films in 2019 and pushed into pressurised bulk Ruddlesden-Popper crystals from 2023 - have joinedthe cuprates and the iron-based compounds as a third correlated-oxide family with its own phase diagramand its own open questions. Hydrogen-dominant superhydrides, compressed inside diamond-anvil cells,keep raising conventional phonon-mediated Tc toward room temperature and, on two now-withdrawn accounts, past it; the credibility cost of those two retractions is addressed here directly rather than foldedquietly into a general narrative of progress. A third, mechanistically distinct route has opened in twisted andproximitized graphene, where superconductivity appears without any parent magnetic order and can bedialled in through twist angle and proximity coupling alone. This review draws these threads together: itseparates what is mechanistically established from what remains proposed, weighs the 2019-2026 record ofmajor claims against how well each has actually been reproduced, and asks what stands between the presentlaboratory demonstrations and superconducting devices that could be deployed at scale. Results now confirmed by independent groups are treated differently from single-laboratory reports, and both are kept distinct from claims the literature has since withdrawn.