Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

Kamaraju, N.; Pan, W.; Ekenberg, U.; Gvozdić, Dejan M.; Boubanga-Tombet, S.; Upadhya, P. C.; Reno, John L.; Taylor, Antoinette; Prasankumar, R. P.

doi:10.1063/1.4906282

Cited by 8 publications

(4 citation statements)

References 31 publications

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“…Furthermore, Γ SR is inversely proportional to the carrier effective mass, m * , indicating that SR decay of CR is stronger in narrow bandgap semiconductors, e.g., InSb. In a 2D hole gas (2DHG), on the other hand, weaker SR decay is expected due to the much heavier effective mass; this was confirmed by recent experiments in a highmobility GaAs 2DHG, where Γ SR was comparable with the intrinsic dephasing rate γ ⊥ [167]. In general, SR decay of CR could also happen in 3D semiconductors, but the scattering rate there is expected to be higher because of a continuous spectrum of carriers.…”

Section: Theory Of Superradiant Decay Of Coherent Crmentioning

confidence: 73%

Dicke superradiance in solids [Invited]

et al. 2016

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Recent advances in optical studies of condensed matter systems have led to the emergence of a variety of phenomena that have conventionally been studied in the realm of quantum optics. These studies have not only deepened our understanding of light-matter interactions but also introduced aspects of many-body correlations inherent in optical processes in condensed matter systems. This article is concerned with the phenomenon of superradiance (SR), a profound quantum optical process originally predicted by Dicke in 1954. The basic concept of SR applies to a general N -body system where constituent oscillating dipoles couple together through interaction with a common light field and accelerate the radiative decay of the whole system. Hence, the term SR ubiquitously appears in order to describe radiative coupling of an arbitrary number of oscillators in many situations in modern science of both classical and quantum description. In the most fascinating manifestation of SR, known as superfluorescence (SF), an incoherently prepared system of N inverted atoms spontaneously develops macroscopic coherence from vacuum fluctuations and produces a delayed pulse of coherent light whose peak intensity ∝ N 2 . Such SF pulses have been observed in atomic and molecular gases, and their intriguing quantum nature has been unambiguously demonstrated. In this review, we focus on the rapidly developing field of research on SR phenomena in solids, where not only photon-mediated coupling (as in atoms) but also strong Coulomb interactions and ultrafast scattering processes exist. We describe SR and SF in molecular centers in solids, molecular aggregates and crystals, quantum dots, and quantum wells. In particular, we will summarize a series of studies we have recently performed on semiconductor quantum wells in the presence of a strong magnetic field. In one type of experiment, electron-hole pairs were incoherently prepared, but a macroscopic polarization spontaneously emerged and cooperatively decayed, emitting an intense SF burst. In another type of experiment, we observed the SR decay of coherent cyclotron resonance of ultrahigh-mobility two-dimensional electron gases, leading to a decay rate that is proportional to the electron density. These results show that cooperative effects in solid-state systems are not merely small corrections that require exotic conditions to be observed; rather, they can dominate the nonequilibrium dynamics and light emission processes of the entire system of interacting electrons.

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Section: Theory Of Superradiant Decay Of Coherent Crmentioning

confidence: 73%

Dicke superradiance in solids [Invited]

et al. 2016

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“…The higher mobility than our previous report of m~6 10 5 cm 2 V −1 s −1 (t~30 tr ps) for 0.8% strain may be linked to the larger E HH,LH . The apparent oscillation in t THz at different filling factors may be related to the variation in LL occupancy [32][33][34], as the CR linewidth depends on the width of the unoccupied region of the final LL. This point is elucidated in the JDOS description later in the manuscript.…”

Section: Mobilitymentioning

confidence: 99%

Terahertz quantum Hall effect for spin-split heavy-hole gases in strained Ge quantum wells

et al. 2016

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Spin-split heavy-hole gases in strained germanium quantum wells were characterized by polarisationresolved terahertz time-domain spectroscopy. Effective masses, carrier densities, g-factors, transport lifetimes, mobilities and Rashba spin-splitting energies were evaluated, giving quantitative insights into the influence of strain. The Rashba coefficient was found to lower for samples with higher biaxial compressive strain, while heavy-hole mobilities were enhanced to over1.5 10 6 cm 2 V −1 s −1 at 3 K. This high mobility enabled the observation of the optical quantum Hall effect at terahertz frequencies for spin-split two-dimensional heavy-holes, evidenced as plateaux in the transverse magnetoconductivity at even and odd filling factors.

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“…THz TDS combined with magnetic field at low temperature provides a well-established method to further investigate and understand the dynamical properties of carriers in 2D electronic systems. Recently, it has been found that the cyclotron resonance frequency exhibits a nonlinear dependence on the applied magnetic field using THz MO spectroscopy in a 2D hole gas [12]. Most recently, it was reported that the LLs of electrons and MO transport properties in a 2D material can be significantly modulated by placing it onto a substrate, and the electron-impurity scatterings should not be neglected [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Substrate dependent terahertz magneto-optical properties of monolayer WS₂

et al. 2021

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Terahertz (THz) magneto-optical (MO) properties of monolayer (ML) tungsten disulfide ( W S 2 ), placed on different substrates and subjected to external magnetic fields, are studied using THz time-domain spectroscopy (TDS). We find that the THz MO conductivity exhibits a nearly linear response in a weak magnetic field, while a distinctly nonlinear/oscillating behavior is found in strong magnetic fields owing to strong substrate-induced random impurity scattering and interactions. The THz MO response of ML W S 2 depends sensitively on the choice of the substrates, which we trace back to electronic localization and the impact of the substrates on the Landau level (LL) spectrum. Our results provide an in-depth understanding of the THz MO properties of ML W S 2 /substrate systems, especially the effect of substrates, which can be utilized to realize atomically thin THz MO nano-devices.

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Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

Cited by 8 publications

References 31 publications

Dicke superradiance in solids [Invited]

Dicke superradiance in solids [Invited]

Terahertz quantum Hall effect for spin-split heavy-hole gases in strained Ge quantum wells

Substrate dependent terahertz magneto-optical properties of monolayer WS₂

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Terahertz magneto-optical spectroscopy of a two-dimensional hole gas

Cited by 8 publications

References 31 publications

Dicke superradiance in solids [Invited]

Dicke superradiance in solids [Invited]

Terahertz quantum Hall effect for spin-split heavy-hole gases in strained Ge quantum wells

Substrate dependent terahertz magneto-optical properties of monolayer WS2

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Substrate dependent terahertz magneto-optical properties of monolayer WS₂