graphene was mechanically exfoliated from highly - oriented pyrolytic graphite onto si / sio2 substrates .
surface hybrids were obtained by immersion in a solution of [ fe4(l)2(dpm)6 ] in 1,2-dichloroethane : dichloromethane ( 9/1 , v / v ) at room temperature , followed by washing with isopropanol .
bulk samples of the hybrids were prepared by first sonicating 8.4 mg of graphite powder in 20 ml of the solvent mixture for 48 hrs , followed by adding 11.5 mg of [ fe4(l)2(dpm)6 ] in 20 ml of the same mixture , followed by stirring for 45 min and final filtering through ptfe membranes ( 0.2 m pore size ) .
magnetic measurements were corrected for the diamagnetism of the sample and sample holder , as independently determined .
a home - built micro - squid susceptometer inside a dilution refrigerator was used for zero - field measurements , with extremely small ac field amplitudes ( 50 moe ) and the data corrected by the bare graphene signal .
afm images were acquired with a bruker icon system in tapping mode , using olympus ac200ts cantilevers .
maldi - tof spectra were recorded using a laser pulsed at ~4 hz , while the xps spectra were obtained with a monochromatized al - k source ( 1486.6 ev ) , see si for details .
electronic devices were fabricated using a pmma resist , e - beam lithography and thermally evaporated au / ti .
 controlling the dynamics of spins on surfaces is pivotal to the design of spintronic1 and quantum computing2 devices . 
 proposed schemes involve the interaction of spins with graphene to enable surface - state spintronics3,4 , and electrical spin - manipulation4 - 11 . 
 however , the influence of the graphene environment on the spin systems has yet to be unraveled12 . here 
 we explore the spin - graphene interaction by studying the classical and quantum dynamics of molecular magnets13 on graphene . 
 while the static spin response remains unaltered , the quantum spin dynamics and associated selection rules are profoundly modulated . 
 the couplings to graphene phonons , to other spins , and to dirac fermions are quantified using a newly - developed model . 
 coupling to dirac electrons introduces a dominant quantum - relaxation channel that , by driving the spins over villain s threshold , gives rise to fully - coherent , resonant spin tunneling . 
 our findings provide fundamental insight into the interaction between spins and graphene , establishing the basis for electrical spin - manipulation in graphene nanodevices . 
Methods
Supplementary Material