A review on the exchange bias phenomenon in bulk and nanostructures of Nd2NiMnO6 double perovskite compound

The double perovskite compound Nd₂NiMnO₆ has garnered considerable attention due to its intriguing magnetic properties, particularly the exchange bias effect, which is of great relevance for spintronic and magnetic storage applications. This review provides a comprehensive and comparative analysis of the exchange bias phenomenon observed in various structural forms of Nd₂NiMnO₆ including bulk, nanoparticles, and thin films, emphasizing the distinctions in their origin, magnitude, and tunability. The discussion systematically explores the influence of structural ordering, antisite disorders, interfacial coupling, magnetic anisotropy, grain size, and strain effects on exchange bias behavior. In bulk Nd₂NiMnO₆, exchange bias arises mainly from ferromagnetic/antiferromagnetic interfacial interactions originating due to antisite disorder induced antiphase boundaries. In NdSrNiMnO₆ nanoparticles, exchange bias is described by a core–shell model, where antiferromagnetic cores are surrounded by spin glass shells, and uncompensated spins at the interface contribute to the observed bias. In Nd₂NiMnO₆ thin films, grown on mismatched substrate (LaAlO₃), the exchange bias effect is primarily governed by strain induced antisite disorders leading to ferromagnetic/spin glass interfacial coupling. By correlating these mechanisms across different morphologies, this review highlights how antisite disorder and microstructural engineering critically dictate the exchange bias behavior in Nd₂NiMnO₆ systems. The insights presented here not only deepen the understanding of exchange bias in double perovskite oxides but also offer guidelines for tailoring their magnetic properties for advanced spintronic and multifunctional device applications.