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

Zhang, Liangzhu; Xing, Shucheng; He, Tian; Wu, Wei-Bin; Zhang, An-Lei; Guo, Zhoubin; Das, Pratteek; Zheng, Shuanghao et al. · Adv Mater · 2025

basic_science · Level V

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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<sub>4/3</sub>B<sub>2</sub> nanosheets is reported with intrinsic room-temperature ferromagnetic characteristics by vacancy engineering. These nanosheets are synthesized by etching the bulk MAB phase (Mo<sub>2/3</sub>Y<sub>1/3</sub>)<sub>2</sub>AlB<sub>2</sub> into Mo<sub>4/3</sub>B<sub>2</sub> nanosheets in ZnCl<sub>2</sub> molten salt. The Mo<sub>4/3</sub>B<sub>2</sub> nanosheets show robust intrinsic ferromagnetic properties, with a saturation magnetic moment of 0.044 emu g<sup>-1</sup> 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<sub>4/3</sub>B<sub>2</sub> 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.