Generation of electric polarization with rotating magnetic field in helimagnet ZnCr2Se4

Application of magnetic field (H) can produce the ferroelectric polarization (P) in a proper screw helimagnet, ZnCr2Se4. While rotating H, we observed the cyclic generation of polarization current arising from the change of P in the conical spin structure. Versatile variations of P in magnitude and sign are observed while changing the direction and magnitude of H. The behaviors are ascribed to the rotation of the spin cones and the conserving or reversing spin-helicity upon the flop of the screw propagation vector, as affected by the competition among the magnetic anisotropy, inclination of the cone axis to H, and the P domain-wall stability.