FIGURE 4. Analysis of the relationship between Ni scattering resonances and local .

Spectral surveys were acquired at 4.2 K on two as-grown Ni-doped Bi-2212 samples, both with tunnel junction resistance of 1 G set at V = -100 mV. Using the +18 mV LDOS image of each survey, the locations of Ni resonances were identified by the strong resonance peak at +18 mV in their dI/dV spectra⁶. For 30% of these resonances, the full particle–hole symmetric signature (spatial and spectroscopic) of a Ni resonance⁶ was directly confirmed. The location of the Ni resonances can be correlated with the local value of extracted from these same two surveys. a, The location of the Ni resonances (red dots) superimposed on the simultaneously acquired gap map of an area 600 Å 600 Å. No Ni resonances are observed in regions where > 50 meV. b, Histograms derived from a combined analysis of the above spectral survey on 0.2% Ni-doped Bi-2212, and an independent 568 Å 568 Å survey on 0.5% Ni-doped Bi-2212. For each Ni resonance, the local is determined by the spatial average of over a 13 Å square region centred on the impurity. Using this information, we plot in red a combined histogram of observed Ni resonances versus from both samples. The combined histogram of from the same two surveys is shown in grey.