Magnetic properties of Single Crystal GaFeO3

kappa-Al2O3-type GaFeO3 is a promising multiferroic material due to the coexistence of a large spontaneous magnetization and polarization near room temperature. In the current study, we present the magnetic properties of single crystalline GaFeO3 and compare it with that of epsilon-Fe2O3. Magnetic measurements revealed that spontaneous magnetization appears below 540 K in two steps, similar to that reported for epsilon-Fe2O3. Partial magnetic ordering takes place at 540 K (T-N1), with Fe3+ ions in two distorted octahedral sites ordering antiparallel to one another. Upon further cooling at 200 K (T-N2), the remaining Fe3+ ions in regular octahedra and tetrahedra order antiparallel to one another. Substitution of Ga for Fe in epsilon-Fe2O3 leads to a decrease in T-N1 and T-N2 from 850 to 540 K and from 480 to 200 K, respectively, caused by a dilution of magnetic Fe by nonmagnetic Ga and preferential site occupation of Ga.