First-principles investigations for the electronic and transport properties of zigzag SiC nanoribbons with Fluorine passivation/adsorption

Nanoribbons with different edge functionalization display interesting electronic properties for various device applications. It requires the necessity of exploring the novel passivating elements commensurate to various technological applications. In this direction, here we have compared the effect of H and F-passivation on the edges of zigzag SiC nanoribbons (ZSiCNR) using density functional theory based calculations. Remarkably, present study reveals that F could be used as an effective passivating element for ZSiCNR similar to widely explored H-passivations. Various possible combinations of F/H are found to have stable structural integrity for practical applications. The effect of F-adatom adsorption is also discussed which present peculiar electronic properties. The half-metallic behavior is observed to be realized via F-adsoprtion which is further confirmed with the transport calculations. The obtained negative differential resistance along the spin dependent electron transport pledges towards wide spread applications of considered ZSiCNR interacting with F.

A theoretical study on the structures and electronic and magnetic properties of new boron nitride composite nanosystems by depositing superhalogen Al13 on the surface of nanosheets/nanoribbons

Inorganic boron nitride (BN) nanomaterials possess outstanding physical and chemical characteristics, and can be considered as an excellent building block to construct new composite nanomaterials. In this work, on the basis of the first-principles computations, a new type of composite nanostructure can be constructed by depositing superhalogen Al13 on the surface of low-dimensional BN monolayer or nanoribbons (BNML/BNNRs). All these Al13-modified BN nanosystems can possess large adsorption energies, indicating that superhalogen Al13 can be stably adsorbed on the surface of these BN materials. In particular, it is revealed that independent of the chirality, ribbon width and adsorption site, introducing superhalogen Al13 can endow the BN-based composite systems with a magnetic ground state with a magnetic moment of about 1.00 μB, and effectively narrow their robust wide band gaps. These new superhalogen-Al13@BN composite nanostructures, with magnetism and an appropriate band gap, can be very promising to be applied in multifunctional nanodevices in the near future.

Adsorbing the 3d-transition metal atoms to effectively modulate the electronic and magnetic behaviors of zigzag SiC nanoribbons

On the basis of first-principles computations, we propose a simple and effective strategy through surface-adsorbing 3d-transition metal (TM) atoms, including Ti, Cr, Mn, Fe and Co, to modulate the electronic and magnetic behaviors of zigzag SiC nanoribbons (zSiCNRs), in view of the unique d electronic structures and intrinsic magnetic moments of TM atoms. It is revealed that like applying an electric field, the adsorption of these transition metal atoms can induce an evident change in the electrostatic potential of the substrate zSiCNRs owing to the electron transfer from the TM atom to the substrate. This can break the magnetic degeneracy of zSiCNRs and solely ferromagnetic (FM) or antiferromagnetic (AFM) metallicity and even intriguing FM or AFM half-metallicity can be observed in the TM-modified zSiCNR systems. Moreover, all these modified systems can exhibit considerably large adsorption energies ranging from -0.872 eV to -4.304 eV, indicating their considerably high structural stabilities. These intriguing findings will be advantageous for promoting excellent SiC-based nanomaterials in the practical application of spintronics and multifunctional nanodevices in the near future.

Quasiparticle energies, exciton level structures and optical absorption spectra of ultra-narrow ZSiCNRs

GW quasiparticle energies, exciton structures and optical absorption spectra of ultra-narrow N-ZSiCNRs.

Room-temperature metal-free ferromagnetism, stability, and spin transport properties in topologically fluorinated silicon carbide nanotubes

A new topologically fluorinated armchair single-walled silicon carbide nanotube has been predicted via first principles density functional theory (DFT) and nonequilibrium Green's function method, as well as ab initio molecular dynamic (MD) simulations.

Zigzag nanoribbons of two-dimensional silicene-like crystals: magnetic, topological and thermoelectric properties

The effects of electron-electron and spin-orbit interactions on the ground-state magnetic configuration and on the corresponding thermoelectric and spin thermoelectric properties in zigzag nanoribbons of two-dimensional hexagonal crystals are analysed theoretically. The thermoelectric properties of quasi-stable magnetic states are also considered. Of particular interest is the influence of Coulomb and spin-orbit interactions on the topological edge states and on the transition between the topological insulator and conventional gap insulator states. It is shown that the interplay of both interactions also has a significant impact on the transport and thermoelectric characteristics of the nanoribbons. The spin-orbit interaction also determines the in-plane magnetic easy axis. The thermoelectric properties of nanoribbons with in-plane magnetic moments are compared to those of nanoribbons with edge magnetic moments oriented perpendicularly to their plane. Nanoribbons with ferromagnetic alignment of the edge moments are shown to reveal spin thermoelectricity in addition to the conventional one.

Adsorbing a PVDF polymer via noncovalent interactions to effectively tune the electronic and magnetic properties of zigzag SiC nanoribbons

On the basis of first-principle computations, we first propose a simple and effective strategy through surface-adsorbing a poly(vinylidene fluoride) (PVDF) polymer via noncovalent interactions to tune the electronic and magnetic behaviors of zigzag SiC nanoribbons (zSiCNRs). It is revealed that depositing the strong electron-withdrawing PVDF polymer with a permanent dipole moment can induce the evident change of the electrostatic potential in the substrate zSiCNRs, like applying an electric field. As a result, this kind of noncovalent surface-modification by a polymer can break the magnetic degeneracy of zSiCNRs independent of the adsorption type and position, and sole ferromagnetic metallicity and even antiferromagnetic half-metallicity can be achieved. Moreover, all PVDF-modified zSiCNR systems can exhibit considerable adsorption energies in the range of -0.436 to -1.315 eV, indicating that these joint systems possess high structural stabilities. These intriguing findings will be advantageous for promoting excellent SiC-based nanomaterials in the applications of spintronics and multifunctional nanodevices in the near future.

Spin effects in thermoelectric phenomena in SiC nanoribbons

Using ab initio methods we calculate the thermoelectric and spin thermoelectric properties of zigzag SiC nanoribbons, asymmetrically terminated with hydrogen. Such nanoribbons display a ferromagnetic ground state, with edge magnetic moments oriented in parallel. Both thermopower and spin thermopower have been determined as a function of chemical potential and temperature. To find the thermoelectric efficiency, the total heat conductance has been calculated, i.e. the electronic and phonon contributions. Numerical results for SiC nanoribbons are compared with those for graphene and silicene ones.

Molecular charge transfer by adsorbing TCNQ/TTF molecules via π–π interaction: a simple and effective strategy to modulate the electronic and magnetic behaviors of zigzag SiC nanoribbons

Molecular charge transfer via simple π–π interaction can be an effective strategy to break the magnetic degeneracy of pristine zSiCNRs.

Hybrid structures of a BN nanoribbon/single-walled carbon nanotube: ab initio study

Hybrid structures of a zigzag edge BN nanoribbon/single-walled carbon nanotube, have been studied via standard spin-polarized density functional theory (DFT) calculations as well as ab initio molecular dynamics (MD) simulations.