Superconductivity in Layered Structures of Rare‐Earth Carbide Halides

Densely packed double layers of metal atoms (M = Y, La, Lu), C2 groups in the octahedral holes formed by them, and layers of halogen atoms (X) over those of the M atoms provides a good description of the structure of the M2C2X2 phase shown on the right. The finding that these two-dimensional metallic systems can be super-conducting, can contribute enormously to an understanding of the attraction between conducting electrons in superconductors.