Field-induced magnetoelectric effect in polycrystalline Ba0.5Sr1.5Co2Fe11AlO22 hexaferrite

Magnetoelectric effect, i.e. the magnetic field induced ferroelectricity or the electric field induced magnetization, has attracted considerable attention due to the interesting physics involved and the potential practical applications[1, 2]. Ferroelectricity induced by complex magnetic orders, such as spiral orders, will exhibit giant magnetoelectric effect[3]. It is, thus, expected that Y-type hexafer-rites with the spiral magnetic order can possess both ferroelectricity and ferromagnetism. In this work, we investigated the magnetic field dependence of magnetic and dielectric responses of the polycrystalline Ba
_0.5
Sr
₁
.
₅
Co
₂
Fe
₁₁
AlO
₂₂
hexaferrite. It is found that the spin transverse cone can persist down to zero-H up to 200 K, but at high temperature, a different zero-H phase will appear. The magnetoelectric coefficient α was calculated by α=dP/dH. At 200 K, the maximum value of α near zero field of the sample was 1481 ps/m.