http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Kuklin, A.,Kuzubov, A.,Kovaleva, E.,Mikhaleva, N.,Tomilin, F.,Lee, H.,Avramov, P. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.2
<P>Half-metallic ferromagnetic materials with planar forms are promising for spintronics applications. A wide range of 2D lattices like graphene, h-BN, transition metal dichalcogenides, etc. are non-magnetic or weakly magnetic. Using first principles calculations, the existence of graphene-like hexagonal chromium nitride (h-CrN) with an almost flat atomically thin structure is predicted. We find that freestanding h-CrN has a 100% spin-polarized half-metallic nature with possible ferromagnetic ordering and a high rate of optical transparency. As a possible method for stabilization and synthesis, deposition of h-CrN on 2D MoSe2 or on MoS2 is proposed. The formation of composites retains the half-metallic properties and leads to the reduction of spin-down band gaps to 1.43 and 1.71 eV for energetically favorable h-CrN/MoSe2 and h-CrN/MoS2 configurations, respectively. Calculation of the dielectric functions of h-CrN, h-CrN/MoSe2 and h-CrN/MoS2 exhibit the high transparency of all three low-dimensional nanomaterials. The honeycomb CrN may be considered as a promising fundamental Half-2D material for a variety of potential applications of critical importance.</P>
Avramov, Paul,Kuzubov, Alexander A.,Kuklin, Artem V.,Lee, Hyosun,Kovaleva, Evgenia A.,Sakai, Seiji,Entani, Shiro,Naramoto, Hiroshi,Sorokin, Pavel B. American Chemical Society 2017 The Journal of physical chemistry A Vol.121 No.3
<P>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 pi-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.</P>
Kovaleva, Evgenia A.,Kuzubov, Alexander A.,Avramov, Pavel V.,Kholtobina, Anastasia S.,Kuklin, Artem V.,Tomilin, Felix N.,Sorokin, Pavel B. Elsevier 2017 Computational materials science Vol.139 No.-
<P><B>Abstract</B></P> <P>Atomic and electronic structure of LSMO-based composites with carbon nanotubes were studied by means of density functional theory with respect to the termination of LSMO surface. The deformation of the tubes caused by the lattice mismatch with the substrate leads to a major change in their electronic structure. The surface terminated with Mn-O layer provides much stronger interaction with carbon nanotubes than Sr-O terminated one does. The interaction with transition metal atoms is essential for spin polarization of the nanotube while no spin injection was observed for Sr-O-supported tubes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Kuklin, Artem V.,Kuzubov, Alexander A.,Kovaleva, Evgenia A.,Lee, Hyosun,Sorokin, Pavel B.,Sakai, Seiji,Entani, Shiro,Naramoto, Hiroshi,Avramov, Paul Elsevier 2017 Journal of magnetism and magnetic materials Vol.440 No.-
<P><B>Abstract</B></P> <P>Induced spin polarization of π-conjugated carbon and <I>h</I>-BN low dimensional fragments at the interfaces formed by deposition of pentacene molecule and narrow zigzag graphene and <I>h</I>-BN nanoribbons on MnO<SUB>2</SUB>-terminated LSMO(001) thin film was studied using GGA PBE+U PAW D3-corrected approach. Induced spin polarization of π-conjugated low-dimensional fragments is caused by direct exchange with Mn ions of LSMO(001) MnO-derived surface. Due to direct exchange, the pentacene molecule changes its diamagnetic narrow-band gap semiconducting nature to the ferromagnetic semiconducting state with 0.15eV energy shift between spin-up and spin-down valence bands and total magnetic moment of 0.11μ<SUB>B</SUB>. Direct exchange converts graphene nanoribbon to 100% spin-polarized half-metal with large amplitude of spin-up electronic density at the Fermi level. The direct exchange narrows the <I>h</I>-BN nanoribbon band gap from 4.04 to 1.72eV in spin-up channel and converts the <I>h</I>-BN ribbon semiconducting diamagnetic nature to a semiconducting magnetic one. The electronic structure calculations demonstrate a possibility to control the spin properties of low-dimensional π-conjugated carbon and <I>h</I>-BN fragments by direct exchange with MnO-derived LSMO(001) surface for spin-related applications.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ohtomo, M.,Yamauchi, Y.,Sun, X.,Kuzubov, A.,Mikhaleva, N.,Avramov, P.,Entani, S.,Matsumoto, Y.,Naramoto, H.,Sakai, S. Royal Society of Chemistry 2017 Nanoscale Vol.9 No.6
<P>We report the structural analysis and spin-dependent band structure of hydrogenated boron nitride adsorbed on Ni(111). The atomic displacement studied by using the normal incidence X-ray standing wave (NIXSW) technique supports the H-B(fcc):N(top) model, in which hydrogen atoms are site-selectively chemisorbed on boron atoms and N atoms remain on top of Ni atoms. The distance between the Ni plane and nitrogen plane did not change after hydrogenation, which implies that the interaction between Ni and N is 3d-pi orbital mixing (donation and back-donation) even after hydrogenation of boron. The remaining pi* peaks in near-edge X-ray absorption fine structure (NEXAFS) spectra are a manifestation of the rehybridization of sp(2) into sp(3) states, which is consistent with the N-B-N bonding angle derived from NIXSW measurement. The SPMDS measurement revealed the spin asymmetry appearing on hydrogenated h-BN, which was originated from a p related orbital with back donation from the Ni 3d state. Even though the atomic displacement is reproduced by the density functional theory (DFT) calculation with the H-B(fcc):N(top) model, the experimental spin-dependent band structure was not reproduced by DFT possibly due to the self-interaction error (SIE). These results reinforce the site-selective hydrogenation of boron and pave the way for efficient design of BN nanomaterials for hydrogen storage.</P>
Kovaleva, E.A.,Melchakova, Iuliia,Mikhaleva, N.S.,Tomilin, F.N.,Ovchinnikov, S.G.,Baek, Woohyeon,Pomogaev, V.A.,Avramov, P.,Kuzubov, A.A. Elsevier 2019 The Journal of physics and chemistry of solids Vol.134 No.-
<P><B>Abstract</B></P> <P>Electronic structure and magnetic properties of the family of first-row transition metal dihalides (TM<I>Hal</I> <SUB>2</SUB>, TM = V, Cr, Mn, Fe, Co, Ni; H = Br, I) monolayers were studied by means of density functional theory. Strong electron correlations were taken into account by implementing Hubbard U correction in a simplified scheme proposed by Dudarev et al. (U<SUB>eff</SUB>). U<SUB>eff</SUB> correction essentially affects electronic structure of TM<I>Hal</I> <SUB>2</SUB> widening the band gap and witnessing their highly spin-polarized nature. Two different ligand orientations namely, H and T configurations of monolayers were considered. Unlike others, Fe<I>Hal</I> <SUB>2</SUB> monolayers tend to form H structure when U<SUB>eff</SUB> correction is included.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Atomic and electronic structures of TM<I>Hal</I> <SUB>2</SUB> monolayers were studied by DFT + U method. </LI> <LI> H and T configurations of monolayers were considered. </LI> <LI> Effective Hubbard U correction strongly affects properties of TM<I>Hal</I> <SUB>2</SUB> monolayers. </LI> </UL> </P>