4,866 research outputs found
Photovoltage Detection of Edge Magnetoplasmon Oscillations and Giant Magnetoplasmon Resonances in A Two-Dimensional Hole System
In our high mobility p-type AlGaAs/GaAs two-dimensional hole samples, we
originally observe the B-periodic oscillation induced by microwave (MW) in
photovoltage (PV) measurements. In the frequency range of our measurements (5 -
40 GHz), the period ({\Delta}B) is inversely proportional to the microwave
frequency (f). The distinct oscillations come from the edge magnetoplasmon
(EMP) in the high quality heavy hole system. In our hole sample with a very
large effective mass, the observation of the EMP oscillations is in neither the
low frequency limit nor the high frequency limit, and the damping of the EMP
oscillations is very weak under high magnetic fields. Simultaneously, we
observe the giant plasmon resonance signals in our measurements on the shallow
two-dimensional hole system (2DHS)
Density dependence of microwave induced magneto-resistance oscillations in a two-dimensional electron gas
We have measured the magneto-resistance of a two-dimensional electron gas
(2DEG) under continuous microwave irradiation as a function of electron density
and mobility tuned with a metallic top-gate. In the entire range of density and
mobility we have investigated, we observe microwave induced oscillations of
large amplitude that are B-periodic. These B-periodic oscillations are
reminiscent of the ones reported by Kukushkin \textit{et al}[1] and which were
attributed to the presence of edge-magneto-plasmons. We have found that the
B-periodicity does not increase linearly with the density in our sample but
shows a plateau in the range (2.4-3) 10^{11}\rm cm^{-2} $. In this regime, the
phase of the B-periodic oscillations is found to shift continuously by two
periods.Comment: 5 pages, 4 figure
Theory of the microwave induced zero resistance states in two-dimensional electron systems
The phenomena of the microwave induced zero resistance states (MIZRS) and the
microwave induced resistance oscillations (MIRO) were discovered in the
ultraclean two-dimensional electron systems in 2001 -- 2003 and have attracted
great interest of researchers. In spite of numerous theoretical efforts the
true origin of these effects remains unknown so far. We show that the MIRO/ZRS
phenomena are naturally explained by the influence of the ponderomotive forces
which arise in the near-contact regions of the two-dimensional electron gas
under the action of microwaves. The proposed analytical theory is in agreement
with all experimental facts accumulated so far and provides a simple and
self-evident explanation of the microwave frequency, polarization, magnetic
field, mobility, power and temperature dependencies of the observed effects.Comment: 18 pages, 9 figures, resubmission. Essential modifications/additions:
Section I, Section II.5 and Fig. 5, Section IV, Reference
Nonequilibrium phenomena in high Landau levels
Developments in the physics of 2D electron systems during the last decade
have revealed a new class of nonequilibrium phenomena in the presence of a
moderately strong magnetic field. The hallmark of these phenomena is
magnetoresistance oscillations generated by the external forces that drive the
electron system out of equilibrium. The rich set of dramatic phenomena of this
kind, discovered in high mobility semiconductor nanostructures, includes, in
particular, microwave radiation-induced resistance oscillations and
zero-resistance states, as well as Hall field-induced resistance oscillations
and associated zero-differential resistance states. We review the experimental
manifestations of these phenomena and the unified theoretical framework for
describing them in terms of a quantum kinetic equation. The survey contains
also a thorough discussion of the magnetotransport properties of 2D electrons
in the linear response regime, as well as an outlook on future directions,
including related nonequilibrium phenomena in other 2D electron systems.Comment: 60 pages, 41 figure
Magnetoplasmon resonance in 2D electron system driven into a zero-resistance state
We report on a remarkably strong, and a rather sharp, photoresistance peak
originating from a dimensional magnetoplasmon resonance (MPR) in a high
mobility GaAs/AlGaAs quantum well driven by microwave radiation into a
zero-resistance state (ZRS). The analysis of the MPR signalreveals a negative
background providing experimental evidence for the concept of absolute negative
resistance associated with the ZRS. When a system is further subject to a dc
field, the maxima of microwave-induced resistance oscillations decay away and a
system reveals a state with close-to-zero differential resistance. The MPR
peak, on the other hand, remains essentially unchanged, indicating surprisingly
robust Ohmic behavior under the MPR conditions.Comment: 4 pages, 2 figures; to appear in Phys. Rev. B - Rapid Communication
Microwave photoresistance of a high-mobility two-dimensional electron gas in a triangular antidot lattice
The microwave (MW) photoresistance has been measured on a high-mobility
two-dimensional electron gas patterned with a shallow triangular antidot
lattice, where both the MW-induced resistance oscillations (MIRO) and
magnetoplasmon (MP) resonance are observed superposing on sharp commensurate
geometrical resonance (GR). Analysis shows that the MIRO, MP, and GR are
decoupled from each other in these experiments.Comment: 5 pages, 4 figures, paper accepted by PR
Electrical and radiation characteristics of semilarge photoconductive terahertz emitters
We present experimental characterization of semilarge
photoconductive emitters, including their electrical/photoconductive
parameters and terahertz spectra. A range of emitters
were studied and fabricated on both LT-GaAs and SI-GaAs,
having a variety of electrode geometries. The spatial cone of terahertz
radiation was defined. The dependencies of the photocurrent
and the terahertz power on the bias voltage and the laser power
were determined. A Fourier-transform interferometer is used to
determine the terahertz spectra and to clarify the effects of the
substrate and electrode geometry
- …