Tuning superconductivity by rare-earth element doping in a high temperature superconductor

Superconductivity has wide potential applications including fusion energy, high-speed magnetic trains, and lossless power transmission. However, the feasibility of these applications is limited by the fact that known superconductors only exist at temperatures far below room temperature and by a lack of understanding of the underlying mechanism behind superconductivity. We explore the superconducting mechanism in a leading high-temperature superconductor by studying its enemies—by understanding how superconductivity can be “killed”, we hope to glean insights into the factors critical to enabling it. We incorporate cerium and praseoudymium, the two elements most effective at suppressing superconductivity in this system without directly substituting copper, into the crystal lattice of Bi₂Sr₂CaCu₂O₈ (Bi-2212). Making use angle-resolved photoemission spectroscopy (ARPES) and single-crystal x-ray diffraction, we investigate the electronic and structural properties of the doped and undoped systems, including charge doping, modulations in the superstructure, substitution site of the Ce/Pr atoms, and changes to the low-energy electronic structures. In doing this, we hope to extract factors that negatively impact superconductivity. This knowledge can not only inform future studies exploring ways to mitigate these negative factors, but also provide insight into microscopic engineering principles to boost superconductivity towards higher temperatures.