Fig. 2

Spatial distribution of the spin excitation on FeTPP. a Characteristic dI/dV spectra of FeTPP measured over one of the two bright pyrrole groups (blue) and over the central Fe ion (red). As a reference, we add a spectrum acquired over the dark pyrroles with the same tip (dashed gray), showing the complete absence of features in this range. (Setpoint: V = 20 mV, I = 300 pA. Lock-in frequency 938 Hz, modulation 50 μV rms). The insets are 1.7 × 1.7 nm² constant current dI/dV maps at V = −15 mV and V = +15 mV of the topography image shown as inset in b. b Stacking plot of point dI/dV spectra (40 curves, 2.5 nm) along the axis of a FeTPP molecule (as shown in the inset). c Symmetric (G_s = \(\frac{1}{2}\left( {G_{{\mathrm {V}} > 0} + G_{{\mathrm {V}} < 0}} \right)\)) and antisymmetric (G_a = \(\frac{1}{2}\left( {G_{{\mathrm {V}} > 0} - G_{{\mathrm {V}} < 0}} \right)\)) components of the dI/dV spectra of a and their flattened spatial distribution along the axis of the FeTPP molecule, as in b