2 research outputs found
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 (<i>t</i>-VN and <i>h</i>-VN) of 2D VN lattices that have robust intrinsic ferromagnetic properties
and high Curie temperatures. Whereas <i>t</i>-VN has 99.9%
of spin polarization at the Fermi level, <i>h</i>-VN possesses
a half-metallic type of conductivity and keeps it after contact with
semiconducting MoS<sub>2</sub>, which can be used as the substrate
for <i>h</i>-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
Superatom Molecular Orbitals of Endohedral C<sub>82</sub>
Understanding superatom molecular orbital (SAMO) states
in fullerene
derivatives has been in the limelight ever since the first discovery
of SAMOs owing to the fundamental interest in this topic as well as
to the possible applications in molecular switches and other organic
electronics. Nevertheless, very few reports have been published on
SAMO states of larger fullerenes so far. Using density functional
theory, we attempt to partially remedy this situation by presenting
a study on SAMO states in C82 and its Ca and Sc endohedrally
doped derivatives, comparing results with previous relevant findings
for C60. We find that C82 possesses higher SAMO
energies compared to C60, as associated with the symmetry
of the molecule, and that endohedral doping leads to energetically
favorable side positions of Ca and Sc inside the C82 cage.
Among the two, Sc@C82 has more stable SAMO states compared
to Ca@C82 as reflected by the shift in the density of states,
while the charge states are found to be similar. In the case of the
monolayer form, the pz- and 2s-SAMO orbitals
overlap with the nearest neighbors, causing parabolic band dispersion
with the formation of near free electron states and that the SAMO
state energies move closer to the Fermi energy compared to the related
molecules. These findings provide promising information about the
distribution of SAMO states in C82 fullerene, which can
be further relevant in studies of SAMO states of higher fullerenes
and for coming applications of these systems