Vacancies Engineering in Molybdenum Boride MBene Nanosheets to Activate Room‐Temperature Ferromagnetism

Abstract The rapid development of low energy dissipation spintronic devices has stimulated the search for air‐stable 2D nanomaterials possessing room‐temperature ferromagnetism. Here the experimental realization of 2D Mo 4/3 B 2 nanosheets is reported with intrinsic room‐temperature ferromagnetic characteristics by vacancy engineering. These nanosheets are synthesized by etching the bulk MAB phase (Mo 2/3 Y 1/3 ) 2 AlB 2 into Mo 4/3 B 2 nanosheets in ZnCl 2 molten salt. The Mo 4/3 B 2 nanosheets show robust intrinsic ferromagnetic properties, with a saturation magnetic moment of 0.044 emu g −1 at 300 K, while vacancy‐free MoB MBene exhibits paramagnetism. It is elucidated that the Mo‐vacancy defect generates large density of states near the Fermi surface and spontaneously spin‐split bands through first‐principles calculations, which contributes to the non‐zero magnetic moment in Mo 4/3 B 2 nanosheets. This work lays the groundwork for activating the magnetic properties of MBene nanosheets by vacancy engineering, offering the possibilities for development of practical spintronic devices.