9,609 research outputs found
Coulomb Drag and Spin Coulomb Drag in the presence of Spin-orbit Coupling
Employing diagrammatic perturbation theory, we calculate the (charge) Coulomb
drag resistivity and spin Coulomb drag resistivity
in the presence of Rashba spin-orbit coupling.
Analytical expressions for and are
derived, and it is found that spin-orbit interaction produces a small
enhancement to and in the ballistic regime
while is unchanged in the diffusive regime. This enhancement in the
ballistic regime is attributed to the enhancement of the nonlinear
susceptibility (i.e. current produced through the rectification of the thermal
electric potential fluctuations in the passive layer) while the lack of
enhancement in the diffusive regime is due to the suppression by disorder.Comment: 8 pages, 2 figure
Exchange-Rate Systems and Interest-Rate Behaviour: The Experience of Hong Kong and Singapore
The Currency Board System in Hong Kong and the monitoring band system in Singapore are important benchmarks for two different exchange-rate systems. In this paper we consider the implications of the two exchange-rate systems on the interest-rate behaviour of the two economies. We examine the domestic-US interest differentials under the two exchange-rate regimes during the Asian Financial Crisis as well as the pre- and post-crisis periods. Using a bivariate generalized autoregressive conditional heteroscedasticity model, we also investigate whether there is any change in the correlation between the domestic and US interest rates due to the Asian Financial Crisis.
Energy Relaxation of Hot Dirac Fermions in Graphene
We develop a theory for the energy relaxation of hot Dirac fermions in
graphene. We obtain a generic expression for the energy relaxation rate due to
electron-phonon interaction and calculate the power loss due to both optical
and acoustic phonon emission as a function of electron temperature
and density . We find an intrinsic power loss weakly
dependent on carrier density and non-vanishing at the Dirac point ,
originating from interband electron-optical phonon scattering by the intrinsic
electrons in the graphene valence band. We obtain the total power loss per
carrier within the range of electron
temperatures . We find optical (acoustic) phonon
emission to dominate the energy loss for in the density range .Comment: 5 page
Ballistic Hot Electron Transport in Graphene
We theoretically study the inelastic scattering rate and the carrier mean
free path for energetic hot electrons in graphene, including both
electron-electron and electron-phonon interactions. Taking account of optical
phonon emission and electron-electron scattering, we find that the inelastic
scattering time and the mean free path
for electron densities . In particular, we find that the mean free path exhibits a
finite jump at the phonon energy due to electron-phonon
interaction. Our results are directly applicable to device structures where
ballistic transport is relevant with inelastic scattering dominating over
elastic scattering.Comment: 4 page
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