Control of Room-Temperature Magnetoelectric Effect via the Initial Electric Phase State in Sr $_{3}$Co $_{2}$Fe$_{24}$ O$_{41}$ Hexaferrite

The effects of the initial sweeping magnetic field $(H_{\mathrm{i}})$ on the room-temperature magnetoelectric (ME) effect for polycrystalline Z-type hexaferrite Sr $_{3}$ Co $_{2}$ Fe $_{24}$ O $_{41}$ were investigated. The results show that both the electric polarization $(P)$ and ME coefficient $(\alpha)$ can be effectively controlled by $H_{\mathrm{i}}$ via its corresponding initial electric phase state. The $P$ and $\alpha$ reach the maximum 13.5 $\mu$ C/m $^{2}$ and $3.2\times 10^{{-10}}$ s/m, respectively, when sweeping the magnetic field $(H)$ from the low-field ferroelectric region. These values are more than three times those obtained while sweeping $H$ from $-\hbox{6}$ kOe in the ferroelectric-paraelectric transition region. Interestingly, the initial electric state was found to have a memory characteristic for nonvolatile ME response. The present research provides insight for the understanding of ME coupling effect in hexaferrite materials and will give impetus to explore novel ME functional devices.