Giant vertical magnetization shift induced by spin canting in a Co/Ca ₂Ru_0.98Fe_0.02FeO₄ heterostructure

We present a study of exchange bias generated at the interface between a polycrystalline Co film sputtered on a cleavage plane of single-crystal Ca ₂Ru_0.98Fe_0.02FeO₄. The exchange bias is accompanied by an extremely large vertical magnetization shift that is characterized by 60% of the saturation magnetization in a 70-kOe cooling field. This phenomenon is seldom observed in other heterostructures. The effects of cooling-field amplitude and temperature on the exchange bias indicate that the magnetization shift results from a ferromagnetic contribution of canted moments in Ca₂Ru_0.98Fe_0.02O₄. A Type-I training effect is also observed, in which the hysteresis loop shrinks from both sides with cycling of the applied field.