Fig. 1: Temperature–doping (T–x) phase diagram of Nd_1−xSr_xNiO₂ inferred from electrical transport.

T₁ is the temperature below which ρ_ab(T) deviates from the T-linear behaviour found at T≥ 250 K; T₂ and T_n are the temperatures above which ρ_ab(T) deviates from a T² and Tⁿ(n = 1.45 ± 0.05) dependence, respectively; T₀ is the temperature at which ρ_ab(T) shows a minimum (above 5 K); T_c is the critical temperature defined using the 50% ρ_n criterion and \({T}_{{{{\rm{c}}}}}^{{\prime} }\) is the onset temperature of superconducting fluctuations as signalled by a steep upturn in dρ_ab/dT. Error bars reflect the uncertainties derived from two independent extraction methods (see Supplementary Figs. 1 and 2 for details). Open and filled symbols correspond to measurements taken in zero and large (>10 T) magnetic fields, respectively, except for T_c and \({T}_{{{{\rm{c}}}}}^{{\prime} }\) that are extracted from zero-field resistivity data. The T–x phase diagram is dissected at optimal doping x_opt ≈ 0.17 into an underdoped region (UD; x ≤ 0.16) within which the correlation-driven insulating state dρ/dT < 0; grey shading) is found and an overdoped region (OD; x ≥ 0.175) in which a non-Fermi liquid resistivity (Δρ(T) ∝ T^1.45±0.05) is found below T_n ~ 50 K. A small region of T² resistivity, marked by blue shadings, emerges beyond x ≥ 0.275. Finally, an asymmetric fan-shaped region of T-linear resistivity, marked by red shading, is found above the apex of the SC dome. A similar fan of high-T T-linear resistivity is also seen in LSCO (ref. ⁶¹) albeit emerging at a higher temperature.