Tuning superconductivity by rare-earth element doping in Bi-based high T_C cuprate superconductors

Motivated by over three decades of studies on elemental doping of high temperature cuprate superconductors, we explore the superconducting mechanism by studying its enemies. By understanding how superconductivity can be “killed” with elemental substitution, we hope to glean insights into the factors critical to enabling it. We identify cerium and praseodymium as the two elements most effective at suppressing superconductivity in Bi₂Sr₂CaCu₂O₈ (Bi-2212) without directly substituting copper, and incorporate them into the crystal lattice at varying concentrations. Making use of 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 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.