5 research outputs found
Radiation-Induced "Zero-Resistance State" and the Photon Assisted Transport
We demonstrate that the radiation induced "zero-resistance state" observed in
a two-dimensional electron gas is a result of the non-trivial structure of the
density of states of the systems and the photon assisted transport. A toy model
of a structureless quantum tunneling junction where the system has oscillatory
density of states catches most of the important features of the experiments. We
present a generalized Kubo-Greenwood conductivity formula for the photon
assisted transport in a general system, and show essentially the same nature of
the transport anomaly in a uniform system.Comment: 4 pages, 3 figures. Please send comment to [email protected]. This
version added a paragraph to discuss the implication of negative conductanc
Magnetotransport in two-dimensional electron gas at large filling factors
We derive the quantum Boltzmann equation for the two-dimensional electron gas
in a magnetic field such that the filling factor . This equation
describes all of the effects of the external fields on the impurity collision
integral including Shubnikov-de Haas oscillations, smooth part of the
magnetoresistance, and non-linear transport. Furthemore, we obtain quantitative
results for the effect of the external microwave radiation on the linear and
non-linear transport in the system. Our findings are relevant for the
description of the oscillating resistivity discovered by Zudov {\em et al.},
zero-resistance state discovered by Mani {\em et al.} and Zudov {\em et al.},
and for the microscopic justification of the model of Andreev {\em et al.}. We
also present semiclassical picture for the qualitative consideration of the
effects of the applied field on the collision integral.Comment: 28 pages, 19 figures; The discussion of the role of the effect of the
microwave field on the distribution function is revised (see also
cond-mat/0310668). Accepted in Phys. Rev.
A classical model for the negative dc conductivity of ac-driven 2D electrons near the cyclotron resonance
A classical model for {\em dc} transport of two dimensional electrons in a
perpendicular magnetic field and under strong irradiation is considered. We
demonstrate that, near the cyclotron resonance condition, and for {\em linear}
polarization of the {\em ac} field, a strong change of the diagonal component,
, of the {\em dc} conductivity occurs in the presence of a {\em weak}
nonparabolicity of the electron spectrum. Small change in the electron
effective mass due to irradiation can lead to negative , while the
Hall component of the {\em dc} conductivity remains practically unchanged.
Within the model considered, the sign of depends on the relative
orientation of the {\em dc} and {\em ac} fields, the sign of the detuning of
the {\em ac} frequency from the cyclotron resonance, and the sign of
nonparabolic term in the energy spectrum.Comment: 4 pages, 1 figur
Radiation induced oscillatory Hall effect in high mobility GaAs/AlGaAs devices
We examine the radiation induced modification of the Hall effect in high
mobility GaAs/AlGaAs devices that exhibit vanishing resistance under microwave
excitation. The modification in the Hall effect upon irradiation is
characterized by (a) a small reduction in the slope of the Hall resistance
curve with respect to the dark value, (b) a periodic reduction in the magnitude
of the Hall resistance, , that correlates with an increase in the
diagonal resistance, , and (c) a Hall resistance correction that
disappears as the diagonal resistance vanishes.Comment: 4 pages text, 4 color figure