Fig. 2: Magnetic-field responses of the superconducting SSNO, SCSE_0.06, SCSE_0.12 and SCE_0.2 thin films.

a–h Are ρ(T) under varying magnetic field perpendicular (parallel) to the NiO₂ planes of SSNO, SCSE_0.06, SCSE_0.12 and SCE_0.2 films. Inset of (a) is a schematic of the sample cross-section. Insets of (b–d) show the zoom-in data around the onset of the superconducting transitions: negative magnetoresistance can be seen above the transitions. Insets of (e–h) show the mutual inductance results for each sample, where the superconducting diamagnetic response can be clearly observed. i–l The variation of the upper critical field \({\mu }_{0}{H}_{{{{\rm{c}}}}2\perp }\) and μ₀H_c2// (estimated against the T_c definition described in the main text) of SSNO, SCSE_0.06, SCSE_0.12 and SCE_0.2 fitted with the Ginzburg-Landau (G-L) equations, where applicable. m–p The vortex activation energy U₀/k_B as a function of magnetic field μ₀H for the SSNO, SCSE_0.06, SCSE_0.12 and SCE_0.2 thin films under magnetic fields applied parallel and perpendicular to the NiO₂ planes. The data are fitted with a power-law relationship U₀ ~ H^-α, extracted from the Arrhenius plot of ρ(T) using the thermally activated flux flow (TAFF) model.