Electronic and magnetic properties regulation of finite to infinite half sandwich organo-transition-metal-complexes functionalized graphene

Abstract

Using first principles calculations, we systematically investigated the structural, electronic and magnetic properties of half-sandwiched organo-ligand (OL)-transition metal (TM) ligands functionalized single-layer graphene (SLG) with diverse arrangement patterns, including zero-dimension (0D) TM_nOL– (OL: Bz = C₆H₆, Np = C₁₀H₈, Ant = C₁₄H₁₀, TM = Ti, Cr, Mn, Fe, n = 1, 2, 3) and 1D organometallic molecule wires, [TMC₄H₂]_∞ and [TM₂C₆H₂]_∞. In the studied structures, most TM atoms favor the hollow site of graphene, while a few favor the top site. All systems are chemically stable and the half-sandwiched TM_nOL– ligands are covalently bonded with graphene. Interestingly, most TM_nOL@Gs are ferromagnetic with the largest magnetic moment of 2.96 μ_B for Cr₃Ant@G₇₇. In addition, ferri–ferromagnetic properties are found for Fe₂Np@G₇₇ and Fe₃Ant@G₇₇, while antiferromagnetic properties are found for Ti₃Ant@G₇₇. With the exception of FeBz@G₃₃, all the TMBz@G₃₃ and TMBz@G₆₆ are semiconductors and the band gap of CrBz@G₃₃ is as large as ∼1.0 eV. As for FeBz@G, the gap for graphene at the Dirac point is opened to 0.673 eV, 0.581 eV and 0.148 eV within the 4 × 4, 5 × 5 and 6 × 6 supercell, respectively. Moreover, the band gaps for TM₂Np@G₇₇ and TM₃Ant@G₇₇ are largely reduced due to the increased coverage of TM atoms. Furthermore, robust magnetic and electronic properties are found for [TMC₄H₂]_∞@G and [TMC₆H₂]_∞@G, in which the magnetic moment of [MnC₄H₂]_∞@G and [FeC₆H₂]_∞@G per cell unit is rather large at around 2.36 μ_B and 4.43 μ_B, respectively. Most [TMC₄H₂]_∞@Gs and [TMC₆H₂]_∞@Gs are metals, while [MnC₄H₂]_∞@G is transformed to be a semiconductor.