Linear polarization study of microwave-radiation-induced magnetoresistance oscillations: Comparison of power dependence to theory

Applied Physics Letters

2018

We present a microscopic theory on the observation of a beating pattern in the radiation-induced magnetoresistance oscillations at very low magnetic field. We consider that such a beating pattern develops as a result of the coupling between two oscillatory components: the first is a system of electron Landau states being harmonically driven by radiation. The second is a lattice oscillation, i.e., an acoustic phonon mode. We analyze the dependence of the beating pattern on temperature, radiation frequency and power. We conclude that the beating pattern is an evidence of the radiation-driven nature of the irradiated Landau states that makes them behave as a collective plasma oscillation at the radiation frequency. Thus, the frequency of such plasmons could be tuned from microwave to terahertz in the same nanodevice with an apparent technological application. PACS numbers:Beating patterns show up when there are two oscillatory contributions coexisting and coupled in the same physical system. For instance, beating patterns can be observed in magnetoresistance (R xx ) of two-dimensional electron systems (2DES) when there are two populated conduction electron subbands involved in the transport. This situation gives rise to the well-known magneto-intersubband scattering oscillations (MISO) 1,2 . They can also be obtained in R xx of 2DES with strong Rashba spin-orbit coupling 3,4 . For both cases the two oscillatory subsystems are the two sets of broadened Landau levels of slightly different energies. On the other hand, two important physical effects in magnetotransport of 2DES

mentioning

confidence: 99%

Beating pattern in radiation-induced oscillatory magnetoresistance in 2DES: Coupling of plasmon-like and acoustic phonon modes

Applied Physics Letters

2018

“…As an example of this lack of consensus, the two, in principle accepted theories 28,32 on RIRO are no longer so relevant because they cannot explain basic features such as the 1/4-cycle phase shift in the oscillation minima 1,44 or the sublinear power law dependence of RIRO 18,20 . And they can not explain either more recent experimental evidence, for instance, about polarization 21,22 . Therefore, we have to admit that to date, RIRO and ZRS are still open issues that remain in the cutting edge of condensed matter physics regarding radiation-mater interaction.…”

mentioning

confidence: 82%

Microscopic theory for radiation-induced zero-resistance states in 2D electron systems: Franck-Condon blockade

Applied Physics Letters

2017

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We present a microscopic model on radiation-induced zero resistance states according to a novel approach: Franck-Condon physics and blockade. Zero resistance states rise up from radiationinduced magnetoresistance oscillations when the light intensity is strong enough. The theory starts off with the radiation-driven electron orbit model that proposes an interplay of the swinging nature of the radiation-driven Landau states and the presence of charged impurity scattering. When the intensity of radiation is high enough it turns out that the driven-Landau states (vibrational states) involved in the scattering process are spatially far from each other and the corresponding electron wave functions do not longer overlap. As a result, it takes place a drastic suppression of the scattering probability and then current and magnetoresistance exponentially drop. Finally zero resistance states rise up. This is an application to magnetotransport in two dimensional electron systems of the Franck-Condon blockade, based on the Franck-Condon physics which in turn stems from molecular vibrational spectroscopy. PACS numbers:Radiation-induced magnetoresistance (R xx ) oscillations (RIRO) 1,2 turn up in high mobility two-dimensional electron systems (2DES) under illumination at low temperature (T ∼ 1K) and low magnetic fields (B) perpendicular to the 2DES. When increasing radiation power (P ), maxima and minima oscillations increase but the latter evolve into zero resistance states (ZRS) 1,2 . Many experiments 3-20 and theoretical explanations have been proposed to understand these effects but no consensus among the people devoted to this field has been reached yet. As an example of this lack of consensus, the two, in principle accepted theories 28,32 on RIRO are no longer so relevant because they cannot explain basic features such as the 1/4-cycle phase shift in the oscillation minima 1,44 or the sublinear power law dependence of RIRO 18,20 . And they can not explain either more recent experimental evidence, for instance, about polarization 21,22 . Therefore, we have to admit that to date, RIRO and ZRS are still open issues that remain in the cutting edge of condensed matter physics regarding radiation-mater interaction. And this is especially true in the case of ZRS, maybe the most intriguing and challenging effect that shows up in this field. Despite the fact that plenty of theories have been developed for RIRO, when it comes to ZRS only a few theoretical models have been put forward 23,31,46,50,51 . In general they predict negative R xx , while it was not experimentally confirmed. On the other hand, the most accepted theory on ZRS is based on the formation of current and electrical field domains 46 ; the key is the existence of an inhomogeneous current flowing through the sample due to the presence of a domain structure. Yet, this is a macroscopical model that overlooks any microscopic approach on ZRS.In this letter we develop a microscopic theory for ZRS that is based on the radiation-driven electron orbit model. The model, in t...

“…They are so surprising and intriguing that to date there is not a clear consensus on the physical origin of such remarkable effects. After a lot of experiments and theoretical models we have to admit that the origin of both, specially the one of ZRS, remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Plasmon–Phonon Coupling in Radiation‐Induced Resistance Oscillations: Beating Pattern and Phase Reversal

Physica Status Solidi (b)

2019

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This article presents a theoretical study on the experimental observation of two different kinds of beating patterns in the microwave-induced resistance oscillations at very low magnetic field in a high mobility two-dimensional electron system. In the first pattern there was no phase reversal through the beat, however, the latter experiments present a clear phase reversal of π. Based on a model that considers that the beating pattern is produced as a result of the coupling between a system of electron Landau states harmonically driven by radiation and an acoustic phonon mode, the contradictory results are explained through a different intensity coupling in terms of amplitude. In the scenario of the non-phase-reversal case, the dependence on radiation frequency and temperature is studied as well as the possibility of observation of more than one beat by lowering temperature and microwave power. It is concluded that both results can be explained with the same theoretical model that in turn is based on the microwave-driven electron orbit model that was previously developed to explain microwave-induced resistance oscillations.however the latter [33] presents a phase reversal of π. In this article we try to explain this apparent contradictory behavior based on