Probing of valley polarization in graphene via optical second-harmonic generation

Wehling, T. O.; Huber, A.; Lichtenstein, A. I.; Katsnelson, M. I.

doi:10.1103/physrevb.91.041404

Cited by 48 publications

(42 citation statements)

References 26 publications

(38 reference statements)

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“…These effects were established to be responsible for photoconductivity, high-harmonic generation, and electron photon drag. A similar scenario can be observed in graphene: Indeed, high-harmonic generation [24][25][26], frequency mixing [27], the coherent photogalvanic effect [28], photothermoelectric effects [29,30], electron photon drag [31], the photogalvanic effect [32,33], and valley polarization [34,35] are among them.…”

Section: Theoretical Modelsupporting

confidence: 56%

Dynamics of quasiparticles in graphene under intense circularly polarized light

2015

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A monolayer of graphene irradiated with circularly polarized light suggests a unique platform for surface electromagnetic wave (plasmon-polariton) manipulation. In fact, the time periodicity of the Hamiltonian leads to a geometric Aharonov-Anandan phase and results in a photovoltaic Hall effect in graphene, creating off-diagonal components of the conductivity tensor. The latter drastically changes the dispersion relation of surface plasmonpolaritons, leading to hybrid wave generation. In this paper we present a systematic and self-contained analysis of the hybrid surface waves obtained from Maxwell equations based on a microscopic formula for the conductivity. We consider a practical example of graphene sandwiched between two dielectric media and show that in the one-photon approximation there is formation of propagating hybrid surface waves. From this analysis emerges the possibility of a reliable experimental realization to study Zitterbewegung of charge carriers of graphene. DOI: 10.1103/PhysRevB.91.075419 PACS number(s): 03.65. Pm, 72.80.Vp, 73.20.Mf, 78.67.Wj I. MOTIVATION AND INTRODUCTIONOne of the most fundamental challenges on the way to improving the efficiency of modern electronic devices is increasing the speed of operations. A partial solution to this problem could be found in integration of photonic and electronic components and is known to be a part of nanophotonics and nanoplasmonics [1]. In a technological implementation that relies on magnetic materials, the basic hardware performance is determined by the duration of an electromagnetic pulse to remagnetize magnetic domains [2]. Therefore utilization of a laser instead of an electric current seems promising, as the characteristic time is down to a few femtoseconds. The only limitation encountered on the way to all-optical technologies is related to the transformation of optical energy into electrical energy. However, the problem can be relaxed by exploiting intrinsic modes of a system [3], e.g., surface plasmon-polaritons. Surface plasmon-polaritons are known to be surface electromagnetic waves residing on the interface between two media that exponentially decay away from the surface. These waves transfer electromagnetic energy which is well localized around the surface. The plasma frequency as well as damping can be tuned by geometrical aspects as well as the permittivity of the surrounding space. In materials with a high mobility of charge carriers (metals or semiconductors) the anomalous dispersion stems from the dominant contribution of the electron gas to the polarizability, and plasmons are characterized by rather fast damping. At the same time the use of new materials like graphene [4], which is free of this disadvantage, could be the optimal option.Studying graphene is of great interest because of its potential applications not only in different technological areas but also as a possible substitute for a semiconductor platform which is compatible with widely used planar technology. In fact, contrary to the parabolic dispersion of charge c...

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Section: Theoretical Modelsupporting

confidence: 56%

Dynamics of quasiparticles in graphene under intense circularly polarized light

2015

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“…, which explicitly connects the behavior of the SHG spectrum at double-and single frequencies of the applied light. It is also worth mentioning that the contribution of the Π (2) d αβγ (ω) diagram is missing in [7].…”

Section: Shg Response From Massive Graphenementioning

confidence: 99%

“…A non-zero result for the triangular diagram can be obtained introducing a valley polarization that generates an imbalance between the two valleys, as discussed in Ref. 7.…”

Section: Shg Response From Massive Graphenementioning

confidence: 99%

Resonant optical second harmonic generation in graphene-based heterostructures

2019

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An optical Second-Harmonic Generation (SHG) allows to probe various structural and symmetry-related properties of materials, since it is sensitive to the inversion symmetry breaking in the system. Here, we investigate the SHG response from a single layer of graphene disposed on an insulating hexagonal Boron Nitride (hBN) and Silicon Carbide (SiC) substrates. The considered systems are described by a non-interacting tightbinding model with a mass term, which describes a non-equivalence of two sublattices of graphene when the latter is placed on a substrate. The resulting SHG signal linearly depends on the degree of the inversion symmetry breaking (value of the mass term) and reveals several resonances associated with the band gap, van Hove singularity, and band width. The difficulty in distinguishing between SHG signals coming from the considered heterostrusture and environment (insulating substrate) can be avoided applying a homogeneous magnetic field. The latter creates Landau levels in the energy spectrum and leads to multiple resonances in the SHG spectrum. Position of these resonances explicitly depends on the value of the mass term. We show that at energies below the band-gap of the substrate the SHG signal from the massive graphene becomes resonant at physically relevant values of the applied magnetic field, while the SHG response from the environment stays off-resonant. arXiv:1903.06641v1 [cond-mat.mes-hall]

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“…It attracted a great deal of attention in the investigation of the use of graphene in the valleytronics. Different ways of generating a valley polarized current in graphene were proposed, such as with electromagnetic fields [15,16,17,18], trigonal warping [19,20], line defects [21,22,23], lattice strain [24,25,26,27,28,29,30,31] and also optical fields [32,33]. More recently in 2014, the first experimental observation of a valley current in graphene was performed [34].…”

Section: Introductionmentioning

confidence: 99%

Perfect valley filter controlled by Fermi velocity modulation in graphene

Lins

Lima

2020

Carbon

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In this work we investigate the effects of a Fermi velocity modulation in a valley filter in graphene created by a combination of a magnetic and electric barrier. With the effective Dirac equation of the system, we use the transfer matrix formalism to obtain the transmittance. We verify that the valley transport in graphene is very sensitive to a Fermi velocity modulation, which is able to choose which valley will be filtered with perfect filtering. Also, it is possible to use a Fermi velocity modulation to filter both valleys or to make the valley filter transparent. It reveals that the Fermi velocity is a powerful tool that can be used to tune a graphene valley filter, since it has a total control in its transport properties. *

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Probing of valley polarization in graphene via optical second-harmonic generation

Cited by 48 publications

References 26 publications

Dynamics of quasiparticles in graphene under intense circularly polarized light

Dynamics of quasiparticles in graphene under intense circularly polarized light

Resonant optical second harmonic generation in graphene-based heterostructures

Perfect valley filter controlled by Fermi velocity modulation in graphene

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