Doping of 3d Transition Metals o n Monolayer o f Graphene a nd Borophene

We Study the doping of various metallic 3d transition metal (TM) atoms like iron (Fe), Cobalt (Co), Copper (Cu) and Nickel (Ni) on monolayer of the borophene and graphene. These 2D layers show energy dispersion and metalloid properties because its band gap is very less or near to zero. We explored borophene is semi-metallic with the titled Dirac cone and graphene is semi metallic whose conduction and valence bands meets at Dirac cone. We analyzed the adsorption of 3d transition metal (TM) on the 2D layers through density functional theory (DFT) based calculations. In this paper, we observed the most suitable and acceptable adsorption site for each adatom, and calculated the binding energy per atom, density of states and magnetic moment of resulting borophene and graphene-adatom system. Here, we find that Nickel (Ni) is perfect as electron doping and iron (Fe) is the most effective for magnetically doped borophene. In the case of graphene we find that Co is most suitable for magnetically doping and Cu is best for electron doping.

Robust Dirac spin gapless semiconductors in a two-dimensional oxalate based organic Honeycomb-Kagome lattice

Two-dimensional (2D) ferromagnetic materials with intrinsic and robust spin-polarized Dirac cone are of great interest to explore exciting physics and to realize spintronic devices. Using comprehensive ab initio calculations, herein...

Superconductivity in the two-dimensional nonbenzenoid biphenylene sheet with Dirac cone

During the past decade, two-dimensional materials have attracted much attention in superconductivity due to their feasible physical properties and easy chemical modifications. Herein, we use a recently literature reported novel biphenylene sheet (BP sheet) for investigating superconductivity-related physical properties. The electronic states of BP sheet that appeared near the Fermi level are composed of pz orbital of carbon due to sp2 hybridization. Also, an anisotropic Dirac cone is formed just above the Fermi level by crossing two bands comprised of different carbon atoms. One of the two bands is quasi-flat thus leading to a peak of electronic density of states above the Fermi level. In addition, the rotational-vibration phonon mode of the six-membered carbon ring is strongly coupled with electrons. The electron-phonon coupling induces the superconductivity of 6.2 K in BP sheet. Furthermore, both small uniaxial strains and electronic doping can take the Dirac cone and high electronic density of state close to the Fermi level and further raise the superconducting critical temperature to 27.4 K and 21.5 K, respectively. The obtained result suggests that BP sheet with Dirac fermions and superconductivity can be a potential material for the development of future superconducting devices.

Acoustic Tunneling Study for Hexachiral Phononic Crystals Based on Dirac-Cone Dispersion Properties

Acoustic tunneling is an essential property for phononic crystals in a Dirac-cone state. By analyzing the linear dispersion relations for the accidental degeneracy of Bloch eigenstates, the influence of geometric parameters on opening the Dirac-cone state and the directional band gaps’ widths are investigated. For two-dimensional hexachiral phononic crystals, for example, the four-fold accidental degenerate Dirac point emerges at the center of the irreducible Brillouin zone (IBZ). The Dirac cone properties and the band structure inversion problem are discussed. Finally, to verify acoustic transmission properties near the double-Dirac-cone frequency region, the numerical calculation of the finite-width phononic crystal structure is carried out, and the acoustic transmission tunneling effect is proved. The results enrich and expand the manipulating method in the topological insulator problem for hexachiral phononic crystals.