Exchange-mediated spin–electric control of single molecules on surfaces

Individual magnetic molecules are promising building blocks for quantum technologies owing to their chemical tunability, nanoscale dimensions and ability to self-assemble into ordered arrays. However, exploiting their properties in quantum information processing requires precise local control of their spin. Here we demonstrate spin-electric coupling for two molecular spin systems-iron phthalocyanine (FePc) and Fe-FePc complexes-adsorbed on a surface. We use electron spin resonance combined with scanning tunnelling microscopy to locally address them and electrically tune them using an applied bias voltage. These measurements reveal a nonlinear voltage dependence of the resonance frequency, linked to the energetic position of the molecular orbitals. We attribute this effect to a transport-mediated exchange field from the magnetic tip, providing a large, highly localized and broadly applicable spin-electric coupling mechanism. Finally, we demonstrate that the spin-electric coupling enables all-electrical coherent spin control. In Rabi oscillation measurements of both single and coupled Fe-FePc complexes, we show that the spin dynamics can be tuned using the exchange field, demonstrating a pathway towards electrically controlled quantum operations.