Using first principles calculations, we systematically studied the electronic and magnetic properties of half sandwich organometallic ligand-functionalized single layer graphene, (FeCp)n@SLGs (n = 1, 2), with different adsorption sites and coverage concentrations. Our results show that all the (FeCp)n@SLGs are quite stable having high binding energies. Except the nonmagnetic FeCp@G44-S1, all the complexes are found to be robust ferromagnets. In particular, the magnetic moments of (FeCp)2@G33-D1, (FeCp)2@G33-D2, (FeCp)2@G33-D3 and (FeCp)2@G44-D1 per unit cell are as large as 2.0 μB, 1.64 μB, 2.0 μB and 1.30 μB, respectively. Among the studied systems, spin polarized band gaps are opened in the Dirac points of FeCp@G33-S, (FeCp)2@G33-D1, (FeCp)2@G44-S2, (FeCp)2@G44-S3, and (FeCp)2@G44-D5, in which (FeCp)2@G33-D1 is transformed into an intrinsic semiconductor. Moreover, displacing Fe by Co or Ni element is found to induce an increasement in magnetic moment or induce a transition from metal to half metal.

The energetics and electronic and magnetic properties of G/MS2 hybrid structures embedded with 3d transition metal atoms, TM@(G/MS2) (G = graphene; M = W, Mo; TM = Sc–Ni), have been systematically studied using first-principles calculations. TM atoms were found to be covalently bound to two-sided graphene and MS2 layers with sizable binding energies of 4.35–7.13 eV. Interestingly, a variety of electronic and magnetic properties were identified for these TM@(G/MS2) systems. Except for TM = Ni, all other systems were ferromagnetic, due to exchange splitting of the TM 3d orbitals. In particular, four TM@(G/MoS2) systems (TM = V, Mn, Fe, Co) and three TM@(G/WS2) systems (TM = Mn, Fe, Co) were half-metals or quasi half-metals, while Ni@(G/MoS2) and Ni@(G/WS2) were semiconductors with bandgaps of 33 and 37 meV, respectively. Further quasi-particle scattering theory analysis demonstrated that the origin of semiconducting or half-metallic properties could be well understood from the variation in on-site energy by the transition metal dichalcogenide substrate or the different on-site scattering potential induced by TM atoms. Our findings propose an effective route for manipulating the electronic and magnetic properties of graphene@MS2 heterostructures, allowing their potential application in modern spintronic and electronic devices.

We perform a systematic investigation on the ground state of the easy-plane S=1 spin model with ferromagnetic nearest-neighbor and antiferromagnetic next-nearest-neighbor interactions using the Density Matrix Renormalization Group (DMRG) method. By analyzing the chirality order parameter, the spin correlation function and the spin structure factor, we determine the phase diagram. A chiral phase is identified in an intermediate frustration region even when the anisotropic value Δ is small. In addition, the spin-fluid phase with power-law decaying correlation exists for the anisotropic case when the frustration strength α is small. When α is large, the ground state is of the short-range-ordered incommensurate phase.

The effect of transition metal atoms on the electronic and magnetic properties of defective bilayer graphene (TM@dBLGs, TM = Ti-Fe) have been systematically studied by first principles calculations. Mixed covalent and ionic bonding is demonstrated between transition metal atoms and on-site graphene layers. Except Ti and Fe, all the TM@dBLG systems anchored by V, Cr and Fe atoms are found to be robust ferromagnetic. Different from the metallic pristine BLG, a number of TM@dBLGs are transformed to be semiconductors, of which, the band gaps of GTiG_SV_H, GVG_SV_H and G(N)FeG_SV are about 361 meV, 219 meV and 147 meV, respectively. In comparison, the B/N doped TM@dBLGs exhibit distinct electronic and magnetic properties due to the charge redistribution. Our findings propose an effective route to manipulate the electronic and magnetic properties of graphene, which allows its potential application in modern spintronic and electronic devices.Download high-res image (290KB)Download full-size image

The structural, electronic, and magnetic properties of transition metal atoms intercalated bilayer graphene, [GTMG]x/y, (x, y is integer, TM = Ti, Cr, Mn, Fe) with different TM/carbon hexagons ratios and insertion patterns, are systematically studied by density functional theory calculations. All the studied systems are thermodynamically stable and competitive ionic–covalent bonding characters are dominated in the TM–graphene interaction. Most studied systems are ferromagnetic; particularly, [GCrG]1:18, [GCrG]1:9, [GFeG]1:6(1), and [GTMG]1:6(2) (TM = Cr, Mn, Fe) exhibit large magnetic moment of 4.43, 5.60, 7.02, 10.85, 9.04, and 5.19 μB per unit cell, respectively. In contrast, [GCrG]1:8 and [GFeG]1:8 are ferrimagnetic, while eight other [GTMG]x/y are nonmagnetic. Moreover, five intercalation nanostructures of [GTMG]1:18 (TM = Ti, Mn), [GTMG]1:9 (TM = Ti, Mn) and [GTiG]1:6 are semiconductors with the gaps of 0.141/0.824 eV, 0.413/0.668 eV, and 0.087 eV, respectively. Comparison on different isomers with same TM/carbon hexagons ratios showed that the electronic and magnetic properties of these [GTMG]x/y are largely dependent on the TM atoms arrangement. For thus, an effective way to control the electronic and magnetic properties of graphene based nanostructures is proposed.

We systematically studied the structural, electronic, and magnetic properties of B/N-doped BzTMCp*TMBz/CpTMCp*TMCp (Bz = C6H6; Cp = C5H5; Cp* = C5–xDxH5; D = B, N; x = 1, 2; TM = V, Cr, Mn, Fe) sandwich clusters and their infinite molecular wires using first-principle calculations. It is found that the B/N-doped ligands do not degrade the linear stacked sandwich configurations compared with the pristine hydrocarbon ligand complexes. Different from the N-doped complexes, the B-doped ligands lead to more charge transfers from metal atoms, and such behavior allows for the enhanced structure stabilities and adds the advantage of electronic and magnetic properties manipulation. Moreover, the B-doped ligand makes the one-dimensional sandwich molecular wires conserve half metallic properties of the pristine molecular wires, undergo half metal–semiconductor transition, and vice versa. Thus, a novel strategy for efficient tailoring of the electronic and magnetic properties of metal–ligand sandwich complexes is presented.