Single-band fluorides akin to infinite-layer cuprate superconductors

Abstract Recent experimental discoveries of infinite- and finite-layer nickelate superconductors have highlighted the importance of a single-band $${d}_{{x}²-{y}²}$$ Fermi surface for enabling unconventional superconductivity similar to cuprates. Motivated by this, we use density functional theory (DFT) and dynamical mean-field theory (DMFT) to identify two infinite-layer fluorides—KNiF ₂ and KPdF ₂ —as promising candidates. Both materials exhibit strong correlations, structural stability, a single-band $${d}_{{x}²-{y}²}$$ Fermi surface, and an antiferromagnetic Mott insulating state for the undoped parent compound. However, in KNiF ₂ , overly strong correlations suppress spin fluctuations, preventing the electron pairing and superconducting states at finite temperatures. In contrast, KPdF ₂ offers tunable superconducting behavior. Using dynamical vertex approximation (DΓA), we show that 20% hole doping on SrTiO ₃ and 10% electron doping on MgO substrate yield superconducting transition temperatures of 65 K and 63 K, respectively, demonstrating the material’s potential through doping and substrate engineering.