Fig. 4: Engineering exchange-interaction strength in diradical nanographene dimers.
a From left to right: Chemical structure, nc-AFM image (Resonant frequency: 29 KHz, Oscillation amplitude: 160 pm), Constant-height current image (Bias voltage: 1 mV), and simulated LDOS map of a diradical nanographene dimer with minimum spin density overlap of the two spins. b From left to right: Chemical structure, nc-AFM image (Resonant frequency: 29 KHz, Oscillation amplitude: 160 pm), Constant-height current image (Bias voltage: 1 mV), and simulated LDOS map of a diradical nanographene dimer with maximum spin density overlap of the two spins. c dI/dV spectra spectra taken on the two locations marked in a. The presence of Kondo resonances at each unit in the dimer suggest a negligible exchange interaction. d–e dI/dV spectra and numerical calculated dI2/dV2 spectra taken on the two locations marked in b. Two symmetric peaks have been detected, suggesting an antiferromagnetic coupled ground state with exchange-interaction strength of 42 meV. f Summarized exchange-interaction strength of three dimer configurations C1–C3 marked in Figs. 3 and 4. Scale bars: 0.3 nm.
