Large Polarization Switching and High-Temperature Magnetoelectric Coupling in Multiferroic GaFeO3 Systems.

GaFeO3-type iron oxides are promising multiferroics due to the coexistence of large spontaneous magnetization and polarization near room temperature. However, the high leakage current and difficulties associated with synthesizing single crystals make it difficult to achieve two important features in the system: a large ferroelectric polarization switching and magnetoelectric coupling at a high-temperature region. Herein, we report successful achievement of these features by preparing high-quality Sc-doped GaFeO3 single crystals (ScxGa1-x/2Fe1-x/2O3 with x = 0-0.3) using the floating zone method. The x ≥ 0.05 crystals exhibit a leakage current 104 times lower than the x = 0 crystals, highlighting the importance of Sc doping. Because of the reduced leakage current, the Sc-doped crystals exhibit large ferroelectric polarization switching along the c-axis with a remanent polarization of 22-25 μC/cm2, which is close to the theoretically predicted polarization value of 25-28 μC/cm2. In addition, the Sc-doped crystals exhibit ferrimagnetism with magnetic anisotropy along the a-axis. Furthermore, a magnetic-field-induced modulation of polarization is observed in the x = 0.15 crystal even at a relatively high temperature, i.e., 100 K.