Soft x-ray resonant diffraction study of magnetic structure in magnetoelectric Y-type hexaferrite

The effect of magnetic field on the magnetic structure associated with magnetoelectric properties in a Y-type hexaferrite, Ba_1.3Sr_0.7CoZnFe₁₁AlO₂₂, was investigated by utilizing the soft x-ray resonant diffraction technique. In this hexaferrite, the so-called alternating longitudinal conical phase is stabilized at room temperature and zero magnetic field. Below room temperature, however, this phase is transformed into the so-called transverse conical phase by applying an in-plane magnetic field (≈ 0.3 T). The transverse conical phase persists even after removing the magnetic field. The magnetoelectricity, which is magnetically-induced electric polarization, observed in the hexaferrite is discussed in terms of the temperature-dependent magnetic structure at zero field.