Figure 1.

Phase-coherent electron transport through a porphyrin nanoribbon-graphene device. (a) Simplified scheme of phase-coherent electron transport through a graphene–Ni-FP8 porphyrin nanoribbon–graphene junction (top) and full chemical structure of Ni-FP8 (bottom, THS = trihexylsilyl). In the top panel, solubilizing groups on porphyrins (3,5-bis(trihexylsilyl)phenyl) and pyrenes (dodecyloxy) have been omitted for clarity. (b) Device architecture. The pink rectangular area in the middle represents the local platinum gate electrode under a 10 nm layer of HfO₂ (transparent light blue); the rectangular areas (pink) at both ends represent the source and drain platinum electrodes, which are in contact with the bowtie-shaped graphene (purple). (c) Differential conductance (G = dI_sd/dV_sd) map measured as a function of bias voltage (V_sd) and gate voltage (V_g) and (d) differential conductance as a function of V_g at V_sd = 0 mV (pink curve) and V_sd = 10 mV (blue curve) for Ni-FP8 device 1 at 4.2 K. The conductance is plotted in a logarithmic scale as the ratio to conductance quantum G₀ = 2e²/h, where e is the elementary charge and h is Planck’s constant. The N – 1 charge state is highlighted by a gray diamond.