DOI: 10.1038/nature14004

The technological appeal of multiferroics is the ability to control magnetism with electric field1–3. For devices to be useful, such control must be achieved at room temperature. The only single-phase multiferroicmaterial exhibiting unambiguous magnetoelectric coupling at room temperature is BiFeO3 (refs 4 and 5). Its weak ferromagnetismarises from the canting of the antiferromagnetically aligned spins by the Dzyaloshinskii–Moriya (DM) interaction. Prior theory considered the symmetry of the thermodynamic ground state and concluded that direct 180-degree switching of the DMvector by the ferroelectric polarization was forbidden. Instead, we examined the kinetics of the switching process, something not considered previously in theoretical work. Here we show a deterministic reversal of the DMvector and canted moment using an electric field at roomtemperature. First-principles calculations reveal that the switching kinetics favours a two-step switching process. In each step the DMvector and polarization are coupled and 180-degree deterministic switching of magnetization hence becomes possible, in agreement with experimental observation. We exploit this switching to demonstrate energy-efficient control of a spin-valve device at room temperature. The energy per unit area required is approximately an order of magnitude less than that needed for spin-transfer torque switching.Given that theDMinteraction is fundamental to single phase multiferroics and magnetoelectrics our results suggest ways to engineermagnetoelectric switching and tailor technologically pertinent functionality for nanometre-scale, low-energy-consumption, non-volatile magnetoelectronics.