The possibility to graft nano-objects directly on its surface makesgraphene particularly appealing for device and sensing applications. Here we reportthe design and the realization of a novel device made by a graphene nanoconstrictiondecorated with TbPc2 magnetic molecules (Pc = phthalocyananine), to electricallydetect the magnetization reversal of the molecules in proximity with graphene. Amagnetoconductivity signal as high as 20% is found for the spin reversal, revealing theuniaxial magnetic anisotropy of the TbPc2 quantum magnets. These results depict thebehavior of multiple-field-effect nanotransistors with sensitivity at the single-molecule level
