Spin-polarized Dirac cones and topological nontriviality in a metal–organic framework Ni₂C₂₄S₆H₁₂

Abstract

Dirac cones in the band structure make a great contribution to the unique electronic properties of graphene. But the spin-degeneracy of Dirac cones limits the application of graphene in spintronics. Here, using first-principles calculations, we propose a two-dimensional (2D) metal-organic framework (MOF), Ni2C24S6H12, with spin-polarized Dirac cones at the six corners of the Brillouin zone (BZ). Ferromagnetism is quite stable with a high Curie temperature (630 K) as revealed by Monte Carlo simulation within the Ising model. Taking spin-orbit coupling into account, band gaps are opened up at the Dirac point (5.9 meV) and Γ point (10.4 meV) in the BZ, making Ni2C24S6H12 a Chern topological insulator which is implemented for achieving the quantum anomalous Hall effect. These interesting properties enable Ni2C24S6H12 to be a promising candidate material for spintronics device applications.

Recent advances in Dirac spin-gapless semiconductors

“…76 Owing to the above properties, it is reasonable to consider thiophene as a potential material for use in a 2D MOF system. By means of first-principles calculations, Lin et al 77 Fig. 7) containing 176 atoms to carry out ab initio molecular dynamics (AIMD) simulations, as this kind of system is dynamically stable at room temperature.…”

Dirac Material Graphene

“…All the Dirac species are described by hexagon packing of two-atom primitive cells. However, 'the primitive cell' may be considerably complicated as it takes place in the case of s-triazines with primitive cells composed of either C 6 N 6 or C 12 N 6 , and C 24 N 6 H 12 molecular compositions [24], graphitic carbon nitride (GCN) with C 14 N 10 as a primitive cell [25], beautiful hexagon patterned lace of NiC 8 S 2 H 4 molecules [26], the FeB 2 monolayer with graphene-like boron sheet [27], an impressive number of MXenes [28] (a new class of inorganic 2D compounds [29]), just appeared new compounds InSe [30] and so forth. The conservation of the hexagon packing of primitive cells mentioned above protects the presence of Dirac cones in the electronic spectra of all the species.…”

“…Only two calculations related to GCN C 14 N 10 [25] and metal-organic framework with primitive cell Ni 2 C 24 S 6 H 12 [26] were obtained taking into account that electrons with α and β spins are correlated and separated in space. The open-shell approach immediately revealed the spin-polarization of the electronic spectra just doubling the band number and combining them in α and β sets.…”

Dirac Material Graphene

“…All the Dirac species are described by hexagon packing of two-atom primitive cells. However, 'the primitive cell' may be considerably complicated as it takes place in the case of s-tirazines with primitive cells composed of either C 6 N 6 or C 12 N 6 , and C 24 N 6 H 12 molecular compositions [24], graphitic carbon nitride (GCN) with C 14 N 10 as a primitive cell [25], beautiful hexagon patterned lace of NiC 8 S 2 H 4 molecules [26], the FeB2 monolayer with graphene-like boron sheet [27], an impressive number of MXenes [28] (a new class of inorganic 2D compounds [29]), just appeared new compounds InSe [30] and so forth. The conservation of the hexagon packing of primitive cells mentioned above protects the presence of Dirac cones in the electronic spectra of all the species.…”

“…Virtually all the Dirac spectra discussed above were calculated not paying attention to if the studied system is open-or closed-shell one and exploiting closed-shell formalism. Only calculations related to GCN C 14 N 10 [25] and metal-organic framework with primitive cell Ni 2 C 24 S 6 H 12 [26] were obtained taking into account that electrons with  and  spins are correlated and separated in space. The open-shell approach immediately revealed spinpolarization of the electronic spectra just doubling the band number and combining them in  and  sets.…”