63 research outputs found
Screening effects in the electron-optical phonon interaction
We show that recently reported unusual hardening of optical phonons
renormalized by the electron-phonon interaction is due to the neglect of
screening effects. When the electron-ion interaction is properly screened
optical phonons soften in three dimension. It is important that for
short-wavelength optical phonons screening is static while for long-wavelength
optical phonons screening is dynamic. In two-dimensional and one-dimensional
cases due to crossing of the nonperturbed optical mode with gapless plasmons
the spectrum of renormalized optical phonon-plasmon mode shows split momentum
dependence.Comment: 7 page
Coherent description of electrical and thermal impurity-and-phonon limited transport in simple metals
The electrical resistivity, thermoelectric power and electronic thermal
conductivity of simple (isotropic) metals are studied in a uniform way.
Starting from results of a variational solution of the Boltzmann equation, a
generalized Matthiessen rule is used in order to superpose the inelastic (or
not) electron-phonon and elastic electron-impurity scattering cross sections
("matrix elements"). The temperature dependence relative to these processes is
given through simple functions and physical parameters over the usually
investigated range of temperature for each transport coefficient. The coherence
of such results is emphasized.Comment: 22 pages, 5 figures; to appear in International Journal of Modern
Physics
Coulomb blockade in quantum dots under AC pumping
We study conductance through a quantum dot under Coulomb blockade conditions
in the presence of an external periodic perturbation. The stationary state is
determined by the balance between the heating of the dot electrons by the
perturbation and cooling. We analyze two cooling mechanisms: electron exchange
with the cold contacts and emission of phonons. Together with the usual linear
Ohmic heating of the dot electrons we consider possible effects of dynamic
localization. The combination of the abovementioned factors may result in a
drastic change of the shape of the Coulomb blockade peak with respect to the
usual equilibrium one.Comment: 12 pages, 8 figure
Non-ohmicity and energy relaxation in diffusive 2D metals
We analyze current-voltage characteristics taken on Au-doped indium-oxide
films. By fitting a scaling function to the data, we extract the
electron-phonon scattering rate as function of temperature, which yields a
quadratic dependence of the electron-phonon scattering rate on temperature from
1K down to 0.28K. The origin of this enhanced electron-phonon scattering rate
is ascribed to the mechanism proposed by Sergeev and Mitin.Comment: 7 pages, 6 figure
Plasmon attenuation and optical conductivity of a two-dimensional electron gas
Journal ArticleIn a ballistic two-dimensional electron gas, the Landau damping does not lead to plasmon attenuation in a broad interval of wave vectors q≤kF . Similarly, it does not contribute to the optical conductivity σ(ω,q) in a wide domain of its arguments, EF>ω>qvF , where EF , kF , and vF are, respectively, the Fermi energy, wave vector, and velocity of the electrons. We identify processes that result in the plasmon attenuation in the absence of Landau damping. These processes are: the excitation of two electron-hole pairs, phonon-assisted excitation of one pair, and a direct plasmon-phonon conversion. We evaluate the corresponding contributions to the plasmon linewidth and to the optical conductivity
Effects of Electron-Electron and Electron-Phonon Interactions in Weakly Disordered Conductors and Heterostuctures
We investigate quantum corrections to the conductivity due to the
interference of electron-electron (electron-phonon) scattering and elastic
electron scattering in weakly disordered conductors. The electron-electron
interaction results in a negative -correction in a 3D conductor. In
a quasi-two-dimensional conductor, ( is the thickness, is
the Fermi velocity), with 3D electron spectrum this correction is linear in
temperature and differs from that for 2D electrons (G. Zala et. al., Phys.
Rev.B {\bf 64}, 214204 (2001)) by a numerical factor. In a
quasi-one-dimensional conductor, temperature-dependent correction is
proportional to . The electron interaction via exchange of virtual phonons
also gives -correction. The contribution of thermal phonons interacting
with electrons via the screened deformation potential results in -term and
via unscreened deformation potential results in -term. The interference
contributions dominate over pure electron-phonon scattering in a wide
temperature range, which extends with increasing disorder.Comment: 6 pages, 2figure
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