Greg Stewart/SLAC National Accelerator Laboratory
A SLAC/Stanford study found that a recently discovered family of nickelate superconductors differs in surprising ways from a related family, the cuprates. Both come in 2D oxide planes (red, green, and grey spheres representing copper, nickel and oxygen ions, respectively) separated by layers of a rare earth material (gold spheres). Cuprates are inherently insulators, and even when they’re doped to add free-flowing electrons (blue spheres), as shown here, their electrons rarely leave to interact with other layers of material. But these nickelates are inherently metals. Even in the non-doped state depicted here, their electrons mix with electrons from the rare-earth layers in a way that creates a 3D metallic state.