Dissipationless Multiferroic Magnonics

We propose that the magnetoelectric effect in multiferroic insulators with a coplanar antiferromagnetic spiral order, such as BiFeO₃, enables electrically controlled magnonics without the need of a magnetic field. Applying an oscillating electric field in these materials with a frequency as low as household frequency can activate Goldstone modes that manifest fast planar rotations of spin, whose motion is essentially unaffected by crystalline anisotropy. Combining with spin ejection mechanisms, such a fast planar rotation can deliver electricity at room temperature over a distance of the magnetic domain, which is free from energy loss due to Gilbert damping in an impurity-free sample.