Figure 4.

Transport measurements and the related phase diagram

(A) Temperature-dependent resistivity (2–300 K) measured for representative samples with different doping levels.

(B) Top: phase diagram of Nd_1−xSr_xNiO₂. Open circles (squares) represent T_c of 10% R (T_c of 90% R), as defined to be the temperatures at which the resistivity is 10% (90%) of the one at 20 K. Bottom: phase diagram of La_2−xSr_xCuO₄.

(C) Hall coefficient as a function of x at 20 K, crossing zero between x = 0.175 and 0.2. The inset displays a two-band schematic (electron pocket, e⁻ band; hole pocket, h⁺ band). The arrow indicates the downward shift of the Fermi level E_F with increasing x. Adapted from Li et al.¹⁰⁴

(D) Temperature dependence of resistivity for Nd_1−xSr_xNiO₂ (x = 0, 0.2, 0.4) bulk samples. Adapted from Li et al.¹¹⁶