Fig. 2

Zero bias spectral features. a, b Kondo resonances over the bright regions of Type 1 and Type 2 junctions, respectively. The zero-bias peaks are mostly detected over four PC rings of Type 1 junctions and over three ZZ rings of Type 2 junctions. c Temperature dependence of the Kondo resonance. All spectra were measured over the same PC site. The half width at half maximum (HWHM) at each temperature is extracted by fitting a Frota function (red dashed lines)⁴⁹ and corrected for the thermal broadening of the tip²⁸. The temperature dependence of HWHM was simulated with the empirical expression \(\frac{1}{2}\sqrt {\left( {\alpha k_{\mathrm {B}}T} \right)^2 + \left( {2k_{\mathrm {B}}T_{\mathrm {K}}} \right)^2}\)²⁹, which reproduces the experimental results with a Kondo temperature T_K ~ 6 K and α = 9.5 (Supplementary Note 3). d Magnetic field dependence of a Kondo resonance (over the same PC site) at the field strengths indicated in the figure. e Double-peak features around zero bias over Type 3 junctions. f Split-peak dI/dV features for nanostructures with different sizes, determined by the number of precursor units in each chGNR, labeled L and R in e. The gap width increases with the length of the ribbons (see Supplementary Fig. 16a in Supplementary Note 8). The red dashed lines are fits to our spectra using a model for two coupled spin-1/2 systems³¹. The spectra in c, d were acquired with a metal tip, while the others with a CO-terminated tip