What Do We Know About Iron-Chalcogenide Superconductors for Potential Quantum Computing?

The superconducting iron chalcogenides have recently attracted significant attention due to their unique combination of superconductivity, nontrivial electronic topology, and magnetism within a single material. This convergence raises the possibility of topological superconductivity, which could serve as a platform for hosting Majorana zero modes (MZMs), potentially for fault-tolerant quantum computing. Evidence of MZMs has been reported on the surface of the superconducting iron chalcogenide FeSe_1-xTe_x. In this presentation, I will review recent studies on the bulk and surface states of Fe_1+yTe_1−xSe_x single crystals grown at Brookhaven National Laboratory. These crystals have been extensively utilized worldwide, contributing to numerous studies on the topological properties of iron chalcogenides. I will then present our findings from scanning probes, angle-resolved photoemission spectroscopy (ARPES), and transport measurements conducted on these single crystals. Our research reveals a wide range of compositional inhomogeneity and variability in superconducting and topological properties among the iron chalcogenides, indicating that precise compositional and electronic phase control is crucial for leveraging these materials in quantum computing applications.