Field-Induced Superconductivity in Ce-doped LaSb₂

Breaking of time-reversal symmetry by magnetic fields and ordering generally suppresses T_c in spin-singlet superconductors. However, in rare cases, an interplay can be engineered which is conducive to magnetic-field induced superconductivity from a metal at zero field. Here we use epitaxial, ultra-thin LaSb₂ doped with Ce to demonstrate a parallel field-induced superconducting dome. Analysis of the dome reveals quantitative insight into the competing depairing effects and their evolution with magnetic field and temperature. At low fields, suppression of magnetic fluctuations on the cerium site enhances superconducting T_c as the magnetic field is increased. As the field is increased further, T_c reaches a maximum and subsequently deacreses due to the depairing effects of the applied field. The evolution of the perpendicular critical field is analyzed and reveals anomalous temperature dependence that can also be explained by the polarization of magnetic impurities. The experiments therefore realize a platform in which various pair-breaking regimes can be dynamically tuned between, allowing access to an underexplored interplay between magnetism and superconductivity in thin-film crystalline superconductors.