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.