Lightwave valleytronics in a monolayer of tungsten diselenide

Langer, Fabian; Schmid, Christoph; Schlauderer, S.; Gmitra, Martin; Fabian, Jaroslav; Nagler, Philipp; Schüller, Christian; Korn, Tobias; Hawkins, Peter G.; Steiner, J. T.; Huttner, Ulrich; Koch, S. W.; Kira, M.; Huber, Rupert

doi:10.1038/s41586-018-0013-6

Cited by 262 publications

(162 citation statements)

References 45 publications

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“…electron correlation. We predict that eh-PER should be ubiquitous in a large range of extreme nonlinear phenomena of current interest, such as HHG with elliptical drivers [1,3,4,8,27,35,56,57] and systems with large Berry curvatures [58], as well as high-order sideband generation [59][60][61][62]. The identification of eh-PER and its effect on the harmonic emission profiles, as well as the formulation of the ERM, provides new insights into the HHG process in solids and could potentially stimulate new experiments.…”

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confidence: 93%

Imperfect Recollisions in High-Harmonic Generation in Solids

2020

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We theoretically investigate high-harmonic generation in hexagonal boron nitride with linearly polarized laser pulses. We show that imperfect recollisions between electron-hole pairs in the crystal give rise to an electron-hole-pair polarization energy that leads to a double-peak structure in the subcycle emission profiles. An extended recollision model (ERM) is developed that allows for such imperfect recollisions, as well as effects related to Berry connections, Berry curvatures, and transition-dipole phases. The ERM illuminates the distinct spectrotemporal characteristics of harmonics emitted parallel and perpendicularly to the laser polarization direction. Imperfect recollisions are a general phenomenon and a manifestation of the spatially delocalized nature of the real-space wave packet, they arise naturally in systems with large Berry curvatures, or in any system driven by elliptically polarized light.

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confidence: 93%

Imperfect Recollisions in High-Harmonic Generation in Solids

2020

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“…Recent advances in mid-infra-red and terahertz laser sources have demonstrated the generation of non-perturbative high-order harmonics from solids, including semiconductors, dielectrics, and nano-structures below their damage threshold. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] With the pioneering work of Ghimire et al, 2 high-harmonic generation (HHG) in solids offers fascinating avenues to probe light-driven electron dynamics in solids on attosecond timescale, [15][16][17][18][19][20] and to image energy band-dispersion of solids. 6,10,21 Moreover, due to the high electron density in solids in comparison to gases, HHG from solids may be superior for higher harmonic yield.…”

Section: Introductionmentioning

confidence: 99%

High-harmonic generation from spin-polarised defects in solids

et al. 2020

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The generation of high-order harmonics in gases enabled to probe the attosecond electron dynamics in atoms and molecules with unprecedented resolution. Extending these techniques to solids, which were originally developed for atomic and molecular gases, requires a fundamental understanding of the physics that has been partially addressed theoretically. Here, we employ timedependent density-functional theory to investigate how the electron dynamics resulting in high-harmonic emission in monolayer hexagonal boron nitride is affected by the presence of vacancies. We show how these realistic spin-polarised defects modify the harmonic emission and demonstrate that important differences exist between harmonics from a pristine solid and a defected solid. In particular, we found that the different spin channels are affected differently by the presence of the spin-polarised point defect. Moreover, the localisation of the wavefunction, the geometry of the defect, and the electron-electron interaction are all crucial ingredients to describe high-harmonic generation in defected solids.npj Computational Materials (2020) 6:10 ; https://doi.

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“…This work opens the door to explore the possibility of performing tomography of complex energy bands [40], to detect coherent effects in light-field-driven currents [41,42], to study nonadiabatic dynamics in graphene during high-harmonic generation [43], and to investigate topological and valleytronics properties in two-dimensional materials [44].…”

Section: Resultsmentioning

confidence: 99%

Attosecond x-ray transient absorption in condensed-matter: a core-state-resolved Bloch model

2019

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Attosecond transient absorption is an ultrafast technique that has opened the possibility to study electron dynamics in condensed matter systems at its natural timescale. The extension to the x-ray regime permits one to use this powerful technique in combination with the characteristic element specificity of x-ray spectroscopy. At these timescales, the coherent effects of the electron transport are essential and have a relevant signature on the absorption spectrum. Typically, the complex lightdriven dynamics requires a theoretical modeling for shedding light on the time-dependent changes in the spectrum. Here we construct a semiconductor Bloch equation model for resolving the lightinduced and core-electron dynamics simultaneously, which enables to easily disentangle the interband and intraband contributions. By using the Bloch model, we demonstrate a universal feature on attosecond x-ray transient absorption spectra that emerges from the light-induced coherent intraband dynamics. This feature is linked to previous studies of light-induced Fano resonances in atomic systems.relied on time-dependent density functional theory approaches [13], which has provided good results in comparison with experiments [5,8]. However, the disentanglement of intraband and interband dynamics is not straightforward and adds an extra difficulty in the interpretation of the numerical results.On the other hand, semiconductor Bloch equations (SBE) [14-17] have been successfully applied to describe the nonlinear response of semiconductors and two-dimensional materials under the interaction of intense IR and mid-IR laser pulses [18][19][20][21][22][23], and also to model ultrafast studies [6]. This many-body theory offers clear advantages for understanding and interpreting the induced complex dynamics, such as separating the intraband and interband contribution as well as reducing the numerical effort. There is still an ongoing debate about the underlying mechanisms of high-harmonic generation in solids and their intrinsic interband and intraband nature [24][25][26][27]. In this context, theoretical approaches that allow to disentangle both contributions are desirable.In this work we present an extension of the standard SBE theory to the x-ray regime, named core-stateresolved Bloch equations (cBE), by including core-hole states. Using cBE, the induced dynamics driven by the IR pump and the x-ray probe pulse can be efficiently resolved. We demonstrate a universal feature of the pumpinduced intraband dynamics on the attosecond x-ray transient absorption spectra in condensed-matter systems. This intraband effect is originated from the coherent lightwave electron transport prior to decoherence by scattering interactions or core-hole decay, and it can be connected to previous works on light-induced Fano spectral lineshapes in atomic systems [28]. This effect is important when the time of the attosecond excitation or the core-hole decay overlaps with the IR laser pulse. We also discuss the importance of this effect on ultrafast studies with mid-I...

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Lightwave valleytronics in a monolayer of tungsten diselenide

Cited by 262 publications

References 45 publications

Imperfect Recollisions in High-Harmonic Generation in Solids

Imperfect Recollisions in High-Harmonic Generation in Solids

High-harmonic generation from spin-polarised defects in solids

Attosecond x-ray transient absorption in condensed-matter: a core-state-resolved Bloch model

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