Ablation laser fluence as an effective parameter to control superconductivity in Ba1−xKxBiO3 films

Potassium doping in insulating BaBiO3 induces superconductivity, with high superconducting transition temperatures, Tc, of up to 31 K in bulk. We investigated growth control of superconducting properties of BKBO films, by varying laser fluence using pulsed laser deposition technique. As cation stoichiometry, especially potassium concentration in BKBO films, was sensitively changed with laser fluence, we were able to precisely control Tc of BKBO films. Following the trend of the bulk phase diagram, Tc showed the highest value of 24.5 ± 0.5 K at the optimal stoichiometry. This result can provide optimal guidance for the synthesis of high-quality BKBO films, and demonstrates the effectiveness of laser fluence to study emerging superconducting phenomena in PLD-grown complex oxide thin films.