The manipulation of single magnetic molecules may enable new strategies for high-density information storage and quantum-state control. However, progress in these areas depends on developing techniques for addressing individual molecules and controlling their spin. Here, we report success in making electrical contact to individual magnetic N@C(60) molecules and measuring spin excitations in their electron tunnelling spectra. We verify that the molecules remain magnetic by observing a transition as a function of magnetic field that changes the spin quantum number and also the existence of non-equilibrium tunnelling originating from low-energy excited states. From the tunnelling spectra, we identify the charge and spin states of the molecule. The measured spectra can be reproduced theoretically by accounting for the exchange interaction between the nitrogen spin and electron(s) on the C(60) cage.

SynthesisFig. S1. Steps in the synthesis protocols, described in detail in the Methods section of the main text. Additional Experimental DetailsAs verification of the ability of our apparatus to produce results consistent with those published previously, we measured several molecules studied by Venkataraman and collaborators. In Fig. S2 we show results for four diaminoalkanes (with 3, 4, 10, and 12 carbons). The conductance values we obtain are in good agreement with the previous measurements.1 A linear fit to log(G) as a function of the number of methylene groups yields a conductance decay constant of 0.91 ± 0.03 per methylene group, which is in excellent agreement with the value reported by Venkataraman et al. 1 These data also show that we are able to measure conductance values as low as 1 × 10 --6 G 0.