Figure 1

The histogram for about 2000 conductance measurements at $T\sim 5$ K in zero field and in a magnetic field of 250 Oe applied in parallel to the Ni wires.Reuse & Permissions

Figure 2

(a) The conductance (upper panel) and the differential conductance $dI/dV$ (lower panel) in the final stage of breaking, which are measured simultaneously. The four lower panels show the evolution of $dI/dV$ for the regions I, II, III, and IV in the conductance. (b) Effect of magnetic field of $H=250$ Oe on the differential conductance where the magnetic field is applied in parallel with the Ni wire during the stretching. The lower panels show the evolution for the regions V, VI, VII, and VIII in the conductance. The dotted lines are fits by Eq. (1).Reuse & Permissions

Figure 3

Representative spectra of $dI/dV$ from $G\left(0\right)\sim 1.8G_0$ to $\sim$85$G_0$, where $G$(0) increases from (a) to (f). The $dI/dV$ spectra in (d), (e), and (f) enlarge the zero-bias anomaly, while the insets show the whole image. All spectra exhibit the Fano resonance with the anomaly at around zero bias, which can be fitted by the Fano line shape in Eq. (1).Reuse & Permissions

Figure 4

(a) $G\left(0\right)$ dependence of $T_K$ distribution, which is estimated at 14 different $G\left(0\right)$ values from fitting dozens of the conductance curves for each $G\left(0\right)$. To look at the distribution clearly, the distribution is plotted in ten steps, where the counts summed in 10 K steps of $T_K$ are divided by the maximum counts for the step at each $G\left(0\right)$. (b) Histogram of $T_K$ below 15$G_0$ and above 15$G_0$. The continuous line shows the fit of the data to the log-normal distributions of $T_K$, where most frequent values are $T_K=60$ K below 15$G_0$ and $T_K=36$ K above 15$G_0$. (c) The temperature dependence of the amplitude for the zero-bias anomaly, which is obtained by dozens of the conductance curves between 30$G_0$ and 40$G_0$ at each temperature. The continuous lines in the inset show the representative curves at 1.9, 3.5, 6.0, and 10 K.Reuse & Permissions