Enhanced Exchange Bias Effect by Modulating Relative Ratio of Magnetic Ions in Y₂Co_2−xMn_xO₆ (x = 1.0–1.9)

It has recently been reported that the exchange bias (EB) phenomenon in double-perovskite Y₂CoMnO₆ ceramic arises from additional antiferromagnetic (AFM) clusters formed by the anti-sites of ionic disorders in the dominant ferromagnetic (FM) phase. To extensively examine the role of ionic orders and versatile magnetic interactions, we measure the magnetic properties of Y₂Co_{2 − x}Mn_xO₆ (x = 1.0–1.9) compounds with different relative ratios of the magnetic ions. Upon increasing the ratio of Mn ions, the FM transition temperature is gradually lowered with a greatly enhanced EB effect for x ≥ 1.4. The measurement of heat capacity and AC magnetic susceptibility in the compound with x = 1.5 suggests the formation of magnetic cluster-glass state from short-range FM order with comparable AFM clusters generated by the formation of Mn³⁺–O²⁻–Mn³⁺ bonds. The dependence of the EB effect on the cooling field reveals the maximum EB field at 2 K to be H_EB = 3.19 kOe. The large EB effect originates from the adjusted proportions of FM and AFM phases and the improved interfacial pinning of exchange coupling in the cluster-glass state. Our results, based on intricate magnetic correlations and phases, provide essential clues for exploring suitable ceramic compounds for magnetic functional applications.