270 research outputs found
Gas Doping on the Topological Insulator Bi2Se3 Surface
Gas molecule doping on the topological insulator Bi2 Se3 surface with
existing Se vacancies is investigated using first-principles calculations.
Consistent with experiments, NO2 and O2 are found to occupy the Se vacancy
sites, remove vacancy-doped electrons and restore the band structure of a
perfect surface. In contrast, NO and H2 do not favour passivation of such
vacancies. Interestingly we have revealed a NO2 dissociation process that can
well explain the speculative introduced "photon-doping" effect reported by
recent experiments. Experimental strategies to validate this mechanism are
presented. The choice and the effect of different passivators are discussed.
This step paves the way for the usage of such materials in device applications
utilizing robust topological surface states
Controllable magnetic correlation between two impurities by spin-orbit coupling in graphene
Two magnetic impurities on the edge of a zigzag graphene nanoribbon strongly
interact with each other via indirect coupling, which can be mediated by
conducting carriers. By means of Quantum Monte Carlo (QMC) simulations, we find
that the spin-orbit coupling and the chemical potential in
system can be used to drive the transition of local-spin exchange from
ferromagnetism to anti-ferromagnetism. Since the tunable ranges for
and in graphene are experimentally reachable, we thus open the
possibilities for its device application. The symmetry in spatial distribution
is broken by the vertical and the transversal spin-spin correlations due to the
effect of spin-orbit coupling, leading to the spatial anisotropy of spin
exchange, which distinguish our findings from the case in normal Fermi liquid.Comment: 7 pages, 3 figures and 1 table. This paper has been accepted in
Scientific Report
The absorption spectrum of hydrogenated silicon carbide nanocrystals from ab initio calculations
The electronic structure and absorption spectrum of hydrogenated silicon
carbide nanocrystals (SiCNC) have been determined by first principles
calculations. We show that the reconstructed surface can significantly change
not just the onset of absorption, but the \emph{shape} of the spectrum at
higher energies. We found that the absorption treshold of the reconstructed
SiCNs cannot be accurately predicted from traditional density functional theory
calculations.Comment: 4 pages, 3 figures, 1 tabl
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