2,100 research outputs found
On the temperature dependence of ballistic Coulomb drag in nanowires
We have investigated within the theory of Fermi liquid dependence of Coulomb
drag current in a passive quantum wire on the applied voltage across an
active wire and on the temperature for any values of . We assume
that the bottoms of the 1D minibands in both wires almost coincide with the
Fermi level. We come to conclusions that 1) within a certain temperature
interval the drag current can be a descending function of the temperature ;
2) the experimentally observed temperature dependence of the drag
current can be interpreted within the framework of Fermi liquid theory; 3) at
relatively high applied voltages the drag current as a function of the applied
voltage saturates; 4) the screening of the electron potential by metallic gate
electrodes can be of importance.Comment: 7 pages, 1 figur
Low temperature electron-phonon resonance in dc-current-biased two-dimensional electron systems
Effects of resonant acoustic phonon scattering on magnetoresistivity are
examined in two-dimensional electron systems at low temperatures by using a
balance-equation magnetotransport scheme direct controlled by the current. The
experimentally observed resonances in linear resistivity are shown to result
from the conventional bulk phonon modes in a GaAs-based system, without
invoking leaky interface phonons. Due to quick heating of electrons, phonon
resonances can be dramatically enhanced by a finite bias current. When the
electron drift velocity increases to the speed of sound, additional and
prominent phonon resonance peaks begin to emerge. As a result, remarkable
resistance oscillation and negative differential resistivity can appear in
nonlinear transport in a modest mobility sample at low temperatures, which is
in agreement with recent experiments.Comment: 7 pages, 5 figures, published versio
Low Field Magnetic Response of the Granular Superconductor LaSrCuO
The properties of the low excitation field magnetic response of the granular
high temperature (HTSC) superconductor LaSrCuO have been analyzed at low
temperatures. The response of the Josephson currents has been extracted from
the data. It is shown that intergrain current response is fully irreversible,
producing shielding response, but do not carry Meissner magnetization. Analysis
of the data shows that the system of Josephson currents freezes into a glassy
state even in the absense of external magnetic field, which is argued to be a
consequence of the d-wave nature of superconductivity in LaSrCuO. The
macroscopic diamagnetic response to very weak variations of the magnetic field
is shown to be strongly irreversible but still qualitatively different from any
previously known kind of the critical-state behaviour in superconductors.
A phenomenological description of these data is given in terms of a newly
proposed ``fractal'' model of irreversibility in superconductors.Comment: LATEX, twocolumns, 22 pages including 20 eps-figure
- …