Nonlocal magnetoelectric switching in spiral multiferroics

Magnetoelectric multiferroics, which host both magnetism and ferroelectric polarization, enable switching of the magnetic order by electric fields, which is vital for spintronics and information storage devices. Spiral multiferroics have long held a promise for electric control of magnetization, although how the magnetic switching occurs under an applied electric field remains enigmatic. We find that, in contrast to all known bulk ferroics, where switching dynamics is confined to domain walls, in spiral multiferroics it can have a nonlocal nature. Such dynamics requires not only the rotation of spins within walls but also in an entire adjacent domain. This unprecedented nonlocal dynamics, where the outermost wall accelerates as it gets closer to the surface, gives faster switching in miniature devices. The inner walls do not move at all, giving a vanishing dielectric response. Our findings establish a paradigm of nonlocal switching dynamics in ferroic materials.