Figure 1

(Color online) (a) Typical $17\times 17{\text{nm}}^2$ STM image on a BiO surface of Bi2212 taken at the sample bias voltage $\left(V_{\text{B}}\right)$ of 300 mV and the setup current $\left(I_{\text{set}}\right)$ of 100 pA. (b) Typical tunneling spectra taken at a Zn site (red) and at a site far from Zn site (black) which are scaled by the conductance at the $V_{\text{B}}=+100\text{mV}$. [(c)–(f)] Typical normalized conductance maps at $-1.5\text{mV}$ $\left[g\left(\mathbf{r},-1.5\text{mV}\right)/g\left(\mathbf{r},+100\text{mV}\right)\right]$ taken on $17\times 17{\text{nm}}^2$ regions in four samples which are (c) OD87K, (d) UD83K, (e) UD76K, and (f) pristine, respectively. In these maps, the contrast has been fixed for the comparison among them. (g) A high spatial resolution $g\left(\mathbf{r},-1.5\text{mV}\right)$ map around a Zn site. (h) A schematic illustration of the ${\text{CuO}}_2$ plane. The sites showing the local maximum in the conductance map in (g) marked by red (bold) circles in (h). These figures indicate that the local maximum appear at the Zn, second NN, and third NN sites.Reuse & Permissions

Figure 2

(Color) [(a)–(c)] Gap maps on the same regions as in Figs. 1c, 1d, 1e, respectively. The sites showing Zn resonance are superimposed on the gap maps as the light blue spheres. (d) The average spectrum associated with each $\Delta$, where the color of each gap-average spectrum corresponds to the color scale used in all gap maps. The spectra are normalized by the conductance value at $+100\text{mV}$.Reuse & Permissions

Figure 3

(Color) Statistical analysis of local $\Delta$ on (a) OD87K, (b) UD83K, and (c) UD76K, respectively. In these analyses, we collected both the data in the regions shown in Fig. 1 and those in other regions. The total areas used in the analyses are $57\times 57{\text{nm}}^2$ [(a) OD87K], $48\times 48{\text{nm}}^2$ [(b) UD83K], and $59\times 59{\text{nm}}^2$ [(c) UD76K], respectively. Gray bars in all figures show the histograms of the local $\Delta$ in overall regions including the site showing the Zn resonance. On the other hand, the colored bars show the histograms of the local $\Delta$ at only the sites showing the Zn resonance. We determined the number of the Zn resonance sites per Cu atom to be 0.42 [(a) OD87K], 0.37 [(b) UD83K], and 0.15% [(c) UD76K], respectively, by counting the resonance sites in all regions.Reuse & Permissions