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Resonant phonon scattering in quantum Hall systems driven by dc electric fields.
W Zhang1, M A Zudov, L N Pfeiffer
1School of Physics and Astronomy, University of Minnesota, Minneapolis, MN 55455, USA.
Physical Review Letters
|February 1, 2008
Summary
We found that applying a DC electric field significantly alters acoustic phonon scattering in 2D electron systems. This field can tune resistance oscillations and enhance phonon resonances, even at low temperatures.
Area of Science:
- Condensed matter physics
- Solid-state physics
Background:
- Two-dimensional electron systems (2DES) exhibit unique electronic properties due to quantum confinement.
- Landau levels arise from applying a magnetic field to 2DES, leading to quantized energy states.
- Acoustic phonon scattering plays a crucial role in electron dynamics and transport properties.
Purpose of the Study:
- To investigate the influence of DC electric fields on resonant acoustic phonon scattering in 2DES.
- To understand the interplay between DC-induced effects, Landau levels, and impurity scattering.
- To explore the nonlinear DC response and extreme transport regimes.
Main Methods:
- Utilizing DC excitation to spatially tilt Landau levels in 2DES.
- Measuring resistance changes under varying DC electric fields and temperatures.
- Analyzing the nonlinear DC response and electron drift velocity effects.
Main Results:
- DC electric fields were observed to strongly modify phonon resonances, converting resistance maxima to minima and vice versa.
- Phonon resonances were dramatically enhanced in the nonlinear DC response, detectable even at low temperatures.
- A resistance maximum was observed as electron drift velocity approached the speed of sound, alongside a DC-induced zero-differential resistance state.
Conclusions:
- DC-induced (de)tuning of resonant acoustic phonon scattering, coupled with inter-Landau level impurity scattering, explains most observed phenomena.
- The study highlights the significant impact of DC electric fields on electron-phonon interactions in 2DES.
- Novel transport phenomena, including zero-differential resistance, were revealed under specific DC excitation conditions.
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