Periodical polarization reversal modulation in multiferroic MnWO4 under high magnetic fields

We report polarization reversal periodically controlled by the electric field in multiferroic MnWO4with a pulsed field up to 52 T. The electric polarization cannot be reversed by successive opposite electric fields in low magnetic fields(< 14 T) at 4.2 K, whereas polarization reversal is directly achieved by two opposite electric fields under high magnetic fields(< 45 T). Interestingly, the polarization curve of rising and falling fields for H∥u(magnetic easy axis) is irreversible when the magnetic field is close to 52 T. In this case, the rising and falling polarization curves can be individually reversed by the electric field, and thus require five cycles to recover to the initial condition by the order of the applied electric fields(+E,-E,-E, +E, +E). In addition, we find that ferroelectric phase Ⅳ can be tuned from parallel to antiparallel in relation to ferroelectric phase AF2 by applying a magnetic field approximated to the c axis.