Low-Magnetic-Field Control of Electric Polarization Vector in a Helimagnet

The mutual control of the electric and magnetic properties of a solid is currently of great interest because of the possible application for novel electronic devices. We report on the low-magnetic-field (for example, B values of ±30 milliteslas) control of the polarization ( P ) vector in a hexaferrite, Ba 2 Mg 2 Fe 12 O 22 , which shows the helimagnetic spin structure with the propagation vector k 0 parallel to [001]. The B -induced transverse conical spin structure carries the P vector directing perpendicular to both B and k 0 , in accord with the recently proposed spin-current model. Then, the oscillating or multidirectionally rotating B produces the cyclic displacement current via the flexible handling of the magnetic cone axis.