Ferroelectric and Magnetic Properties in Room-Temperature Multiferroic GaxFe2-xO3 Epitaxial Thin Films

摘要

GaFeO3-type iron oxide is a promising room-temperature multiferroic material due to its large magnetization. To expand its usability, controlling the ferroelectric and magnetic properties is crucial. In this study, high-quality GaxFe2-xO3 (x = 0-1) epitaxial films are fabricated and their properties are systematically investigated. All films exhibit room-temperature out-of-plane ferroelectricity, showing that the coercive electric field (E-c) decreases monotonically with x. Additionally, the films show in-plane ferrimagnetism with a Curie temperature (TC) > 350 K at x = 0-0.6. The coercive magnetic field (H-c) decreases with x at x <= 0.6, but shows a constant value at x > 0.6, whereas the saturated magnetization (M-s) increases with x at x = 0.6, but decreases with x at x > 0.6. X-ray magnetic circular dichroism reveals that the large magnetization at x <= 0.6 is derived from Fe3+ (3d5) at octahedral sites. The controllable range of the E-c, H-c, and M-s values at room temperature (400-800 kV cm(-1), 1-8 kOe, and 0.2-0.6 mu(B)/f.u.) is very wide and differs from those of well-known multiferroic BiFeO3. Furthermore, the GaxFe2-xO3 films exhibit room-temperature magnetocapacitance effects, indicating that adjusting TC near room temperature is useful to achieve large room-temperature magnetocapacitance behavior.