The magnetic and dielectric properties of multiferroic Sr- substituted Zn2-Y hexagonal ferrites

The magnetic and dielectric properties of Sr-substituted Zn$_{2}$-Y hexagonal ferrites (Ba$_{2 - x}$Sr$_{x}$Zn$_{2}$Fe$_{12}$O$_{22}$, $1.0 \le x \le 1.5$) are studied in this paper. Sr substitution will lead to the variation of cation occupation, which influences both the magnetic and electric properties. As Sr content $x$ rises from 1.0 to 1.5, magnetic hysteresis loop gets wider gradually and the permeability drops rapidly due to the transformation from ferrimagnetic to antiferromagnetic phase. Moreover, permittivity rises with increasing Sr content. Under a certain external magnetic field, the phase transition of helical spin structure of Ba$_{0.5}$Sr$_{1.5}$Zn$_{2}$Fe$_{12}$O$_{22}$ at about 295\,K seems to open a possibility for the room-temperature ferroelectricity induced by magnetic field. But its low resistivity prevents the observation of ferroelectric and magnetoelectric properties at room-temperature.