Enhancement of room-temperature magnetization in GaFeO3-type single crystals by Al and Sc doping

GaFeO3-type oxides are promising multiferroic materials due to the coexistence of spontaneous magnetization and ferroelectric polarization properties at room temperature. As these ferroic properties feature a large anisotropy, single crystals are required. However, the magnetization of GaFeO3-type single crystals remains low at room temperature. In this study, we largely enhanced the magnetization at room temperature of GaFeO3-type single crystals by increasing the Fe content and co-doping Sc3+ and Al3+. Single crystals of AlxSc0.1−xGa0.6Fe1.3O3 (x = 0.01–0.04) were prepared using the optical floating-zone method. The single crystals were rod-shaped, with a diameter and length of ∼6 mm and 7 cm, respectively. X-ray diffraction measurements confirmed the ferroelectric polarization of the crystals. In addition, they exhibited room-temperature ferrimagnetism, with Curie temperature in the range of 326–338 K; the crystals exhibit magnetic anisotropy along the a-axis. The magnetization of the single crystal at 300 K and 0.3 kOe was 13 emu g−1, which is over ten times larger than those of previously reported single crystals with GaFeO3-type crystal structure.