Temperature dependence of the Magnetic Structure in Co -Ti doped M-type Hexaferrites

The field of magnetoelectric (ME) multiferroics is driven by the promise of controlling magnetism using applied electric fields, offering the possibility of a new generation of ultra-low power data storage. Among the few room temperature single-phase ME multiferroics reported, hexaferrites show potential for device applications as they exhibit a low field ME effect at room temperature. In samples of SrTi2Co2Fe8O19, Wang et al observed a large electric field-control of the magnetization even without a magnetic bias field, which should not be possible for a longitudinal conical order assuming the normally dominant inverse Dzyaloshinskii-Moriya interaction is responsible for the polarization. However, a unique magnetic-ion induced displacive electric polarization has been recently established in (Ba,Sr)Fe12O19 which may explain the findings of Wang et al. It is also clear from recent literature that the temperature dependent magnetic order in these materials if still far from being well understood hence we are tackling this problem by combined neutron and resonant soft X-ray diffraction studies.
In this proposal we aim to investigate the magnetic order in Co-Ti doped M-type hexaferrites and give a definitive answer to the mechanism of electric polarization in this system by characterising the conical order and its temperature / field dependence