First-Principles Study on the Half-Metallicity of New MXene Materials NdNT (T = OH, O, S, F, Cl, and Br).

This work systematically studied the structure, magnetic and electronic properties of the MXene materials NdN and NdNT (T = OH, O, S, F, Cl, and Br) via first-principles calculations based on density functional theory. Results showed that NdNT (T = OH, O, S, F, Cl, and Br) have half-metallic characteristics whose half-metallic band gap width is higher than 1.70 eV. Its working function ranges from 1.83 to 6.50 eV. The effects of strain on its magnetic and electronic structures were evaluated. Results showed that the structure of NdNT (T = OH, O, S, and Br) transitions from a ferromagnetic half-metallic semiconductor to a ferromagnetic metallic and ferromagnetic semiconductor under different strains. By contrast, the structures of NdNF and NdNS were observed to transition from a half-metallic semiconductor to a ferromagnetic metallic semiconductor under different strains. Calculations of the electronic properties of different proportions of the surface functional groups of NdNT (T = OH, O, and F; = 0.5, 1(I, II), and 1.5) revealed that NdNO has the characteristics of semiconductors, whereas NdNO(II) possesses the characteristics of half-metallic semiconductors. The other structures were observed to exhibit the characteristics of metallic semiconductors. Prediction of NdNT (T = OH, O, S, F, Cl, and Br) increases the types of lanthanide MXene materials. They are appropriate candidate materials for preparing spintronic devices.