Biphenylene Molecules with Iron Atoms: A New Half-Metallic Ferromagnetic MOFs for Advanced Spintronic Devices

Abstract

Metal–organic frameworks (MOFs) represent a versatile class of materials with tunable physical properties, including magnetism. However, designing atomically precise, large-scale two-dimensional (2D) MOFs with strong magnetic coupling remains a major theoretical and experimental challenge. In this theoretical study, we investigate a novel 2D MOF structure based on biphenylene (BP) molecules coordinated with iron atoms (Fe-BP), using first-principles density functional theory (DFT) calculations. Our results reveal that the Fe-BP system exhibits a strong magnetic exchange interaction, with an exchange energy of approximately 233 meV, indicating robust ferromagnetic coupling. The system is predicted to be both ferromagnetic and half-metallic, and displays a large magnetic anisotropy energy (MAE) of –47.81 meV, favoring in-plane magnetization. These magnetic properties originate from strong π–d electron interactions between the organic ligands and the iron centers. The calculations also suggest the presence of complex spin interactions beyond conventional superexchange mechanisms. This theoretical work highlights the potential of Fe-BP as a promising platform for two-dimensional metallic and ferromagnetic engineering, combined with its high magnetic stability. It also highlights its potential as a promising platform for high-temperature 2D spintronic applications, with tunable magnetic and electronic properties.