Superconductivity in nickel-based materials is powered by a bizarre "five-spin polaron" state.
Scientists used to think superconductivity followed simple pairing models where electrons move in unison. In bilayer nickelates, a complex multi-spin structure involving five different magnetic signals acts as the foundation for the effect. This state places a specific hole at the oxygen atoms between layers, which dictates how the electricity flows without resistance. Understanding this five-spin arrangement helps explain why some materials become superconductors at much higher temperatures than others. It challenges existing theories and provides a new blueprint for designing the next generation of lossless power grids.
Interlayer Five-Spin Polaron in Superconducting Bilayer Nickelates
arXiv · 2605.02891
The discovery of high-$T_c$ superconductivity in Ruddlesden-Popper nickelates has sparked substantial effort towards understanding unconventional electronic states beyond a traditional cuprate-like d^9 configurational ground state. An understanding of the interplay between magnetic ground states and multi-orbital physics is key for establishing a microscopic mechanism for superconductivity. In the bilayer nickelates, spin density wave (SDW) order is a prominent feature in the non-superconducting