Antisite disorder-induced exchange bias effect in multiferroic Y₂CoMnO₆

Exchange bias effect in the ferromagnetic double perovskite compound Y₂CoMnO₆, which is also a multiferroic, is reported. The exchange bias, observed below 8 K, is explained as arising due to the interface effect between the ferromagnetic and antiferromagnetic clusters created by antisite disorder in this material. Below 8 K, prominent ferromagnetic hysteresis with metamagnetic "steps" and significant coercive field, H_c ≈ 10 kOe are observed in this compound which has a T_c ≈ 75 K. A model based on growth of ferromagnetic domains overcoming the elastic energy of structurally pinned magnetic interfaces, which closely resembles martensitic-like transitions, is adapted to explain the observed effects. The role of antisite disorder in creating the domain structure leading to exchange bias effect is highlighted in the present work.