Recent development on magnetic properties of MnBi alloys

Permanent magnets are one of the essential components of various devices, including computers, power generators, electric cars, wind turbines, and medical equipment. Since NdFeB magnets have exceptional magnetic properties, such as maximal energy product, remanence, and high coercivity, they now dominate the market. However, these magnets rely heavily on rare earth elements (REEs) such as neodymium, dysprosium, and praseodymium, which are susceptible to price swings and supply chain issues. Researchers and industry professionals are thus very interested in creating rare-earth-free (REF) permanent magnets as substitutes for those that rely on REEs. Manganese bismuth (MnBi) is a magnetic material that is not dependent on rare-earth metals. It has attracted attention due to its high temperature stability, suitable saturation magnetization, affordability, and magnetocrystalline anisotropy. This review examines the magnetic properties of MnBi alloys, with a particular focus on their performance in thin-film and nanoparticle forms. The scalability, cost-effectiveness, challenges, research gaps, and future prospects in employing MnBi for advanced permanent magnet applications are discussed in detail. • This review focuses on the magnetic properties of MnBi alloys. • A particular emphasis is paid on their behavior in thin film and nanoparticle forms. • Key developments in synthesis techniques, phase stability, and performance optimization are discussed. • It provides an overview of the current state and challenges in utilizing MnBi for permanent magnet applications.