28 research outputs found
Ab initio and nuclear inelastic scattering studies of FeSi/GaAs heterostructures
The structure and dynamical properties of the FeSi/GaAs(001) interface
are investigated by density functional theory and nuclear inelastic scattering
measurements. The stability of four different atomic configurations of the
FeSi/GaAs multilayers is analyzed by calculating the formation energies and
phonon dispersion curves. The differences in charge density, magnetization, and
electronic density of states between the configurations are examined. Our
calculations unveil that magnetic moments of the Fe atoms tend to align in a
plane parallel to the interface, along the [110] direction of the FeSi
crystallographic unit cell. In some configurations, the spin polarization of
interface layers is larger than that of bulk FeSi. The effect of the
interface on element-specific and layer-resolved phonon density of states is
discussed. The Fe-partial phonon density of states measured for the FeSi
layer thickness of three monolayers is compared with theoretical results
obtained for each interface atomic configuration. The best agreement is found
for one of the configurations with a mixed Fe-Si interface layer, which
reproduces the anomalous enhancement of the phonon density of states below 10
meVComment: 14 pages, 9 figures, 4 table
Lattice dynamics of endotaxial silicide nanowires
Self-organized silicide nanowires are considered as main building blocks of
future nanoelectronics and have been intensively investigated. In
nanostructures, the lattice vibrational waves (phonons) deviate drastically
from those in bulk crystals, which gives rise to anomalies in thermodynamic,
elastic, electronic, and magnetic properties. Hence, a thorough understanding
of the physical properties of these materials requires a comprehensive
investigation of the lattice dynamics as a function of the nanowire size. We
performed a systematic lattice dynamics study of endotaxial FeSi nanowires,
forming the metastable, surface-stabilized -phase, which are in-plane
embedded into the Si(110) surface. The average widths of the nanowires ranged
from 24 to 3 nm, their lengths ranged from several m to about 100 nm. The
Fe-partial phonon density of states, obtained by nuclear inelastic scattering,
exhibits a broadening of the spectral features with decreasing nanowire width.
The experimental data obtained along and across the nanowires unveiled a
pronounced vibrational anisotropy that originates from the specific orientation
of the tetragonal -FeSi unit cell on the Si(110) surface. The
results from first-principles calculations are fully consistent with the
experimental data and allow for a comprehensive understanding of the lattice
dynamics of endotaxial silicide nanowires.Comment: 9 pages, 7 figures, 3 table
Ab initio calculations of magnetic structure and lattice dynamics in Fe/FeSi multilayers
The first principles study on PtC compound
WOS: 000257450300008We have studied structural, thermodynamic, elastic, and electronic properties of platinum carbide (PtC) in zinc-blende and rock-salt structures by performing ab initio calculations within the LDA approximations. Particularly, we have focused on the structural and the pressure dependence of elastic moduli and related quantities. The other basic key properties, such as the lattice constant, cohesive energy, the phase transition pressure, bulk modulus and its pressure derivative are also repeated and compared with the other available experimental and theoretical works. (c) 2008 Elsevier B.V. All rights reserved