Magnetoelectric effects in Co-Ti Co-doped M-Type Barium Hexaferrites

Magnetoelectric multiferroic materials possess both magnetic and ferroelectric properties couple, which have attracted intensive investigations from both fundamental and application potentials such as new concept sensors or high density storage devices. However, update to now most of the single phase multiferroics can only work at low temperatures and large operation magnetic fields. In recent years, people found that hexaferrites with conical spiral spin structure can both improved the working temperature and reduced operation magnetic field. In this work, we applied high level Co-Ti codopping into M-type hexaferrites to form BaFe12-2xCoxTixO19 (x=0~4) ceramics by solid state reaction. Their magnetic, electrical, magnetodielectric and magnetoelectric properties have been investigated by a combination of Physical Properties Measurement System (PPMS) and other testing instruments, which are controlled by a LabVIEW program. It was revealed that Co-Ti codoping can significantly change the magnetization and coercivity of the BaFe12-2xCoxTixO19. Meanwhile, Co-Ti doping can also greatly suppress the leakage current by about three orders (x2). Notably, we observed apparent magnetic field induced ferroelectricity polarization in some compositions, at temperatures below 100K. Finally, magnetodielectric effect (up to 0.9%) at room temperature were obtained in the co-doped sample (x=2). The present results could provide a new route for exploring new type of multiferroic hexaferrites and their potential applications.