Spin glass behavior and exchange bias effect in GaFeO3-type iron oxide

GaFeO₃-type iron oxide is a promising room-temperature multiferroic material due to its large magnetization and polarization. To expand the scope of its application, it is crucial to control the magnetic properties. Based on introducing the ferromagnetic (FM) Fe₃O₄ in the antiferromagnetic (AFM) GaFeO₃ to build the FM-AFM interface by changing the Ga/Fe ratio, Ga_0.69Fe_1.31O₃ (GFO) was successfully grown by the floating zone method. The resulting sample was characterized by X-ray diffraction (XRD), and its magnetic properties were measured using a superconducting quantum interference device (SQUID). The temperature-dependent AC susceptibility measurement shows that the spin glass-like behavior of GFO at temperatures close to 50 K is a manifestation of the geometrical frustration arising from cation site disorder. In addition, the magnetic property measurement shows that the magnetic transition temperature Tc is at 650 K, which is introduced by Fe₃O₄ and suppresses the ferromagnetic transition around 320 K of GFO. Interestingly, the observed exchange bias effect, which does not exist in the bulk GaFeO₃-type family, is attributed to the formation of an FM/AFM interface due to the existence of FM Fe₃O₄ in the GFO. This study provides a new perspective on the properties of the GaFeO₃-type family for potential applications in spintronic devices.