370 research outputs found
Spin Hall effect in the kagome lattice with Rashba spin-orbit interaction
We study the spin Hall effect in the kagom\'{e} lattice with Rashba
spin-orbit coupling. The conserved spin Hall conductance (see
text) and its two components, i.e., the conventional term
and the spin-torque-dipole term , are numerically
calculated, which show a series of plateaus as a function of the electron Fermi
energy . A consistent two-band analysis, as well as a Berry-phase
interpretation, is also given. We show that these plateaus are a consequence of
the various Fermi-surface topologies when tuning . In particular,
we predict that compared to the case with the Fermi surface encircling the
point in the Brillouin zone, the amplitude of the spin Hall
conductance with the Fermi surface encircling the points is twice
enhanced, which makes it highly meaningful in the future to systematically
carry out studies of the -valley spintronics.Comment: 7 pages, 3 figures. Phys. Rev. B (in press
Magnetic coupling properties of rare-earth metals (Gd, Nd) doped ZnO: first-principles calculations
The electronic structure and magnetic coupling properties of rare-earth
metals (Gd, Nd) doped ZnO have been investigated using first-principles
methods. We show that the magnetic coupling between Gd or Nd ions in the
nearest neighbor sites is ferromagnetic. The stability of the ferromagnetic
coupling between Gd ions can be enhanced by appropriate electron doping into
ZnO:Gd system and the room-temperature ferromagnetism can be achieved. However,
for ZnO:Nd system, the ferromagnetism between Nd ions can be enhanced by
appropriate holes doping into the sample. The room-temperature ferromagnetism
can also be achieved in the \emph{n}-conducting ZnO:Nd sample. Our calculated
results are in good agreement with the conclusions of the recent experiments.
The effect of native defects (V, V) on the
ferromagnetism is also discussed.Comment: 5 pages, 5 figure
Superconductivity in iron telluride thin films under tensile stress
By realizing in thin films a tensile stress state, superconductivity of 13 K
was introduced into FeTe, an non-superconducting parent compound of the iron
pnictides and chalcogenides, with transition temperature higher than that of
its superconducting isostructural counterpart FeSe. For these tensile stressed
films, the superconductivity is accompanied by the softening of the first-order
magnetic and structural phase transition; and also, the in-plane extension and
out-of-plane contraction are universal in all FeTe films independent of sign of
lattice mismatch, either positive or negative. Moreover, the correlations were
found exist between the transition temperatures and the tetrahedra bond angles
in these thin films.Comment: 4 pages, 4 figures, accepted by Physical Review Letter
Effect of Ka-band Microwave on the spin dynamics of electrons in a GaAs/Al0.35Ga0.65As heterostructure
We report experimental results of the effect of Ka-band microwave on the spin
dynamics of electrons in a 2D electron system in a GaAs/Al0.35Ga0.65As
heterostructure, via time-resolved Kerr rotation measurements. While the
microwave reduces the transverse spin lifetime of the bulk GaAs when its
frequency is close to the Zeeman splitting of the electrons in the magnetic
field, it significantly increases that of electrons in the 2D electron system,
from 745 ps to 1213 ps. Such a microwave-enhanced spin lifetime is ascribed to
the microwave-induced electron scattering which leads to a motional narrowing
of spins via DP mechanism
Spin precession and electron spin polarization wave in [001]-grown quantum wells
We theoretically study the spatial behaviors of spin precessions modulated by an effective magnetic field in a two-dimensional electron system with spin-orbit interaction. Through analysis of interaction between the spin and the effective magnetic field, we find some laws of spin precession in the system, by which we explain some previous phenomena of spin precession, and predict a controllable electron spin polarization wave in [001]-grown quantum wells. The shape of the wave, like water wave, mostly are ellipse-like or circle-like, and the wavelength is anisotropic in the quantum wells with two unequal coupling strengths of the Rashba and Dresselhaus interactions, and is isotropic in the quantum wells with only one spin orbit interaction
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