Artem V. Kuklin

Contact-induced spin polarization in BNNT(CNT)/TM (TM=Co, Ni) nanocomposites

The interaction between carbon and BN nanotubes (NT) and transition metal Co and Ni supports was studied using electronic structure calculations. Several configurations of interfaces were considered, and the most stable ones were used for electronic structure analysis. All NT/Co interfaces were found to be more energetically favorable than NT/Ni, and conductive carbon nanotubes demonstrate slightly stronger bonding than semiconducting ones. The presence of contact-induced spin polarization was established for all nanocomposites. It was found that the contact-induced polarization of BNNT leads to the appearance of local conductivity in the vicinity of the interface while the rest of the nanotube lattice remains to be insulating.

Two-Dimensional Lattices of VN: Emergence of Ferromagnetism and Half-Metallicity on Nanoscale

Two-dimensional (2D) ferromagnets with high spin-polarization ratio and high Curie temperature are crucial for developing next-generation spintronic nanodevices. Using first-principles calculations, we predict two polymorphic modifications ( t-VN and h-VN) of 2D VN lattices that have robust intrinsic ferromagnetic properties and high Curie temperatures. Whereas t-VN has 99.9% of spin polarization at the Fermi level, h-VN possesses a half-metallic type of conductivity and keeps it after contact with semiconducting MoS2, which can be used as the substrate for h-VN synthesis and valley polarized contacts. Magnetocrystalline anisotropy energy of 2D VN polymorphs is found to be at least an order larger than those of Fe and Ni bulks. The phonon spectra and ab initio molecular dynamic simulation prove that 2D VN lattices have a high thermodynamic stability. These advantages demonstrate that the VN monolayers should be promising candidates for low-dimensional spintronic devices.

Theoretical Investigation of the Interfaces and Mechanisms of Induced Spin Polarization of 1D Narrow Zigzag Graphene- and h-BN Nanoribbons on a SrO-Terminated LSMO(001) Surface

The structure of the interfaces and the mechanisms of induced spin polarization of 1D infinite and finite narrow graphene- and h-BN zigzag nanoribbons placed on a SrO-terminated La1-xSrxMnO3 (LSMO) (001) surface were studied using density functional theory (DFT) electronic structure calculations. It was found that the π-conjugated nanofragments are bonded to the LSMO(001) surface by weak disperse interactions. The types of coordination of the fragments, the strength of bonding, and the rate of spin polarization depend upon the nature of the fragments. Infinite and finite graphene narrow zigzag nanoribbons are characterized by the lift of the spin degeneracy and strong spin polarization caused by interface-induced structural asymmetry and oxygen-mediated indirect exchange interactions with Mn ions of LSMO support. Spin polarization changes the semiconducting nature of infinite graphene nanoribbons to half-metallic state with visible spin-up density of states at the Fermi level. The h-BN nanoribbon binding energy is weaker than graphene nanoribbon ones with noticeably shorter interlayer distance. The asymmetry effect and indirect exchange interactions cause spin polarization of h-BN nanoribbon as well with formation of embedded states inside the band gap. The results show a possibility to use one-atom thick nanofragments to design LSMO-based heterostructures for spintronic nanodevices with h-BN as an inert spacer to develop different potential barriers.

Theoretical investigation of the structure and properties of the VN(111) monolayer on the MgO(111) surface

The VN(111) monolayer on the MgO(111) surface has been simulated and optimized in terms of the density functional theory (DFT) calculations. The most favorable arrangement of vanadium nitride on the surface of the magnesium oxide plate has been found. The band structure and densities of states for the VN(111) monolayer have been calculated. It has been concluded based on the densities of states for the VN monolayer on the MgO surface that this structure exhibits properties of a diluted magnetic semiconductor.

Theoretical investigation of the adsorption and diffusion of hydrogen on the surface and in the bulk of the intermetallic compound Mg2Ni

The intermetallic compound Mg2Ni as a potential material for hydrogen storage has been investigated theoretically. The sorption and diffusion of a hydrogen atom in the bulk and on the surface of this material, as well as the step-by-step process of dissociative chemisorption of a H2 molecule on the surface, have been considered. The dependence of the sorption energy of atomic hydrogen on the structural characteristics of the intermetallic compound Mg2Ni has been analyzed.