Fig. 4: Non-Fermi-liquid resistivity power law in overdoped Nd_1−xSr_xNiO₂.

a ρ_ab(T) and corresponding derivative dρ_ab/dT of a highly overdoped Nd_1−xSr_xNiO₂ (x = 0.275). A moderate magnetic field of 14 T can suppress SC completely without inducing a noticeable MR. The prominent curvature in dρ_ab/dT suggests that the normal-state ρ_ab(T) can be described by a power-law behaviour Δρ(T) ∝ Tⁿ with 1 < n < 2, for which n = 1.41 ± 0.02 is found. b ρ_ab(T) and d\({\rho }_{ab}^{*}\)/dT (normalised by their respective 50-K values) for 0.25 ≥ x ≥ 0.175. For x = 0.25 and 0.225, extrapolated normal-state zero-field resistivity is shown in open squares (see Supplementary Fig. 12). Faint coloured lines in dρ_ab/dT panels are fits made to the 34-T data between 3T₀ (vertical dashed lines) and 30 K, assuming a power-law resistivity ρ(T) = ρ₀ + α_nTⁿ. c Extracted low-T resistivity power-law exponent n. A constant value of n = 1.45 ± 0.05 (red shading) is found over a wide doping range. d Prefactor of the power-law resistivity α_n versus residual resistivity ρ₀, assuming n = 1.45 for all OD films. The error bars in α_n correspond to the geometric uncertainties of measured samples, typical of 15%. e Main panel: Residual-free resistivity Δρ_ab = ρ_ab(T) − ρ₀ versus T^1.45 for 0.175 ≤ x ≤ 0.275. Inset: Corresponding plot for 0.3 ≤x≤ 0.325. Open and filled symbols are data measured under zero and large applied magnetic fields (34 T for 0.175 ≤ x ≤ 0.25; 14 T for x = 0.275; 12 T for x≥0.30), respectively.