Magnetic and Polar Properties' Optimization in the Magnetoelectric Ga2-xFexO3 Compounds

The influence of the iron content on the magnetic, polar, and magnetoelectric properties of Ga2-xFexO3 (x = 1.0; x = 1.4) polycrystalline samples was studied by a combined magnetic (SQUID) and structural (X-ray and temperature-dependent neutrons diffraction) study. As expected, the samples showed a ferrimagnetic structure, with moments aligned along the c axis. The Neel temperature increases with x, from 210 K for GaFeO3 to 360 K for Ga0.6Fe1.4O3. The magnetic moment is close to 3.8 mu B per iron atom for all compositions. The structural investigations show a decrease in the distortion parameters with increasing iron content, and computation of the polarization with a point-charge model gives a similar significant and temperature-independent value of approximate to 20 mu C/cm(2) for both compositions. This study clearly indicates that magnetic properties can be strongly enhanced by increasing the Fe content in the cell, while the non-negligible polarization value is preserved. Because the magnetoelectric coupling is also predicted to be preserved when increasing the iron content to x = 1.4, this composition is the most appropriate for applications.