Switching of ferrotoroidal domains via an intermediate mixed state in the multiferroic Y-type hexaferrite Ba0.5Sr1.5Mg2Fe12O22

We report a detailed study of the magnetic field switching of ferrotoroidal/multiferroic domains in the Y-type hexaferrite compound Ba0.5Sr1.5Mg2Fe12O22. By combining data from superconducting quantum interference device (SQUID) magnetometry, magnetocurrent measurements, and resonant x-ray scattering experiments, we arrive at a complete description of the deterministic switching, which involves the formation of a temperaturedependent mixed state in low magnetic fields. This mechanism is likely to be shared by other members of the hexaferrite family, and presents a challenge for the development of high-speed read-write memory devices based on these materials.