arXiv subjects

A. T. Hatke

Publications and source records attributed to A. T. Hatke.

30 records · Page 2Linked to original sources

arXiv2011

Multiphoton microwave photoresistance in a high-mobility two-dimensional electron gas

We report on experimental and theoretical studies of microwave-induced resistance oscillations in a two-dimensional electron gas over a wide range of microwave intensities. We observe a distinct crossover from linear to sublinear power dependence of the oscillation amplitude and a concomitant narrowing of the oscillation extrema. To explain our observations we propose a theory based on the quantum kinetic equation at arbitrary microwave power. Taken together, these findings demonstrate a crucial role of multiphoton processes at elevated microwave intensities.

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arXiv2011

Microwave photoresistance in a two-dimensional electron gas with separated Landau levels

Theories of microwave-induced resistance oscillations in high-mobility two-dimensional electron gas predict that with decreasing oscillation order $n$ or with increasing frequency $ω$ the photoresistance maxima should appear closer to the cyclotron resonance harmonics due to increased Landau level separation. In this experimental study we demonstrate that while for a given $ω$ the peaks do move towards the harmonics with decreasing $n$, there is no corresponding movement with increasing $ω$ for a given $n$. These findings show that the positions of the photoresistance maxima cannot be directly linked to the Landau level separation challenging our current understanding of the phenomenon.

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arXiv2011

Giant microwave photoresistivity in a high-mobility quantum Hall system

We report the observation of a remarkably strong microwave photoresistivity effect in a high-mobility two-dimensional electron system subject to a weak magnetic field and low temperature. The effect manifests itself as a giant microwave-induced resistivity peak which, in contrast to microwave-induced resistance oscillations, appears only near the second harmonic of the cyclotron resonance and only at sufficiently high microwave frequencies. Appearing in the regime linear in microwave intensity, the peak can be more than an order of magnitude stronger than the microwave-induced resistance oscillations and cannot be explained by existing theories.

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arXiv2011

Non-linear response of a high mobility two-dimensional electron system near the second harmonic of the cyclotron resonance

Recent experiments on microwave-irradiated high-mobility two-dimensional electron systems revealed a novel photoresistivity peak in the vicinity of the second cyclotron resonance harmonic. Here we report on the nonlinear transport measurements and demonstrate that the peak can be induced by modest dc fields and that its position is not affected even by strong dc fields, in contrast to microwave-induced resistance oscillations that shift to higher magnetic fields. These findings reinforce the notion that the peak cannot be described by existing models and provides important constraints for further theoretical considerations.

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arXiv2011

Hall field-induced resistance oscillations in tilted magnetic fields

We have studied the effect of an in-plane magnetic field on Hall field-induced resistance oscillations in high mobility two-dimensional electron systems. We have found that the oscillation frequency depends only on the perpendicular component of the magnetic field but the oscillation amplitude decays exponentially with an in-plane component. While these findings cannot be accounted for by existing theories of nonlinear transport, our analysis suggests that the decay can be explained by an in-plane magnetic field-induced modification of the quantum scattering rate.

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arXiv2010

Zero differential resistance in two-dimensional electron systems at large filling factors

We report on a state characterized by a zero differential resistance observed in very high Landau levels of a high-mobility two-dimensional electron system. Emerging from a minimum of Hall field-induced resistance oscillations at low temperatures, this state exists over a continuous range of magnetic fields extending well below the onset of the Shubnikov-de Haas effect. The minimum current required to support this state is largely independent on the magnetic field, while the maximum current increases with the magnetic field tracing the onset of inter-Landau level scattering.

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arXiv2009

Non-linear Magnetoresistance Oscillations in Intensely Irradiated Two-Dimensional Electron Systems Induced by Multi-Photon Processes

We report on magneto-oscillations in differential resistivity of a two-dimensional electron system subject to intense microwave radiation. The period of these oscillations is determined not only by microwave frequency but also by its intensity. A theoretical model based on quantum kinetics at high microwave power captures all important characteristics of this phenomenon which is strongly nonlinear in microwave intensity. Our results demonstrate a crucial role of the multi-photon processes near the cyclotron resonance and its harmonics in the presence of strong dc electric field and offer a unique way to reliably determine the intensity of microwaves acting on electrons.

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arXiv2009

Role of electron-electron interactions in nonlinear transport in 2D electron systems

We study the temperature evolution of the non-linear oscillatory magnetoresistance in a high-mobility two-dimensional electron system subject to a strong dc electric field. We find that the decay of the oscillation amplitude with increasing temperature originates primarily from increasing quantum scattering rate entering the Dingle factor. We attribute this behavior to electron-electron interaction effects.

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arXiv2009

Phonon-induced Resistance Oscillations in Very-high Mobility 2D Electron Systems

We report on temperature dependence of acoustic phonon-induced resistance oscillations in very high mobility two-dimensional electron systems. We observe that the temperature dependence is non-monotonic and that higher order oscillations are best developed at progressively lower temperatures. Our analysis shows that, in contrast to Shubnikov-de Haas effect, phonon-induced resistance oscillations are sensitive to electron-electron interactions modifying the single particle lifetime.

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arXiv2009

Temperature Dependence of Microwave Photoresistance in 2D Electron Systems

We report on the temperature dependence of microwave-induced resistance oscillations in high-mobility two-dimensional electron systems. We find that the oscillation amplitude decays exponentially with increasing temperature, as $\exp(-αT^2)$, where $α$ scales with the inverse magnetic field. This observation indicates that the temperature dependence originates primarily from the modification of the single particle lifetime, which we attribute to electron-electron interaction effects.

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arXiv2008

Microwave Photoresistance in dc-driven 2D Systems at Cyclotron Resonance Subharmonics

We study microwave photoresistivity oscillations in a high mobility two-dimensional electron system subject to strong dc electric fields. We find that near the second subharmonic of the cyclotron resonance the frequency of the resistivity oscillations with dc electric field is twice the frequency of the oscillations at the cyclotron resonance, its harmonics, or in the absence of microwave radiation. This observation is discussed in terms of the microwave-induced sidebands in the density of states and the interplay between different scattering processes in the separated Landau level regime.

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arXiv2008

Non-linear magnetotransport in microwave-illuminated two-dimensional electron systems

We study magnetoresistivity oscillations in a high-mobility two-dimensional electron system subject to both microwave and dc electric fields. First, we observe that the oscillation amplitude is a periodic function of the inverse magnetic field and is strongly suppressed at microwave frequencies near half-integers of the cyclotron frequency. Second, we obtain a complete set of conditions for the differential resistivity extrema and saddle points. These findings indicate the importance of scattering without microwave absorption and a special role played by microwave-induced scattering events antiparallel to the electric field.

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