Radiation effects on the electronic properties of bilayer graphene

Morell, E. Suárez; Torres, Luis E. F. Foa

doi:10.1103/physrevb.86.125449

Cited by 128 publications

(69 citation statements)

References 47 publications

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“…In a milestone paper, Haldane envisioned that breaking either or both of these symmetries would open a gap at the Dirac points in graphene, allowing one to tune between a trivial insulator and a Chern insulator 9 . While equilibrium band gap engineering has become a major theme since the first synthesis of monolayer graphene, it was only recently proposed that circularly polarized, high-frequency laser light could turn trivial equilibrium bands into topological nonequilibrium Floquet bands [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] , coined Floquet topological insulator (FTI).…”

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confidence: 99%

Theory of Floquet band formation and local pseudospin textures in pump-probe photoemission of graphene

et al. 2015

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Ultrafast materials science promises optical control of physical properties of solids. Continuous-wave circularly polarized laser driving was predicted to induce a light-matter coupled state with an energy gap and a quantum Hall effect, coined Floquet topological insulator. Whereas the envisioned Floquet topological insulator requires high-frequency pumping to obtain well-separated Floquet bands, a follow-up question regards the creation of Floquet-like states in graphene with realistic low-frequency laser pulses. Here we predict that short optical pulses attainable in experiments can lead to local spectral gaps and novel pseudospin textures in graphene. Pump-probe photoemission spectroscopy can track these states by measuring sizeable energy gaps and Floquet band formation on femtosecond time scales. Analysing band crossings and pseudospin textures near the Dirac points, we identify new states with optically induced nontrivial changes of sublattice mixing that leads to Berry curvature corrections of electrical transport and magnetization.

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confidence: 99%

Theory of Floquet band formation and local pseudospin textures in pump-probe photoemission of graphene

et al. 2015

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“…Searching for such states in solid state materials [8][9][10] has partly gained success; however, candidate materials for TIs are still very limited. Inspiringly, an intriguing method was put forward to realize topologically non-trivial phases in nonequilibrium by applying time-dependent perturbations to trivial phases [11][12][13][14][15][16]. Typical examples are the optically-activated anomalous Hall effect and spin Hall effect in n-doped paramagnetic semiconductors [14], and the so-called Floquet topological insulator (FTI) suggested by Lindner, Refael, and Galitski [16], whose quasienergy spectrum exhibits a single pair of helical edge states due to the on-resonant-light-induced band inversion.…”

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confidence: 99%

Floquet Weyl semimetal induced by off-resonant light

Wang¹,

Wang²,

Shen³

et al. 2014

EPL

138

100

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We propose that a Floquet Weyl semimetal state can be induced in three-dimensional topological insulators, either nonmagnetic or magnetic, by the application of off-resonant light. The virtual photon processes play a critical role in renormalizing the Dirac mass and so resulting in a topological semimetal with vanishing gap at Weyl points. The present mechanism via off-resonant light is quite different from that via on-resonant light, the latter being recently suggested to give rise to a Floquet topological state in ordinary band insulators. [8][9][10] has partly gained success; however, candidate materials for TIs are still very limited. Inspiringly, an intriguing method was put forward to realize topologically non-trivial phases in nonequilibrium by applying time-dependent perturbations to trivial phases [11][12][13][14][15][16]. Typical examples are the optically-activated anomalous Hall effect and spin Hall effect in n-doped paramagnetic semiconductors [14], and the so-called Floquet topological insulator (FTI) suggested by Lindner, Refael, and Galitski [16], whose quasienergy spectrum exhibits a single pair of helical edge states due to the on-resonant-light-induced band inversion. In the bulk FTI spectrum there is an avoided crossing separating the reshuffled valence band from the conduction band.

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“…15). There have also been proposals of Floquet driving of graphene by radiation [16][17][18][19] , Floquet topological insulators and the generation of topologically protected edge states ; some of these aspects have been experimentally studied [43][44][45][46][47][48] .…”

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confidence: 99%

Effects of interactions on periodically driven dynamically localized systems

Agarwala

Sen

2017

Phys. Rev. B

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It is known that there are lattice models in which non-interacting particles get dynamically localized when periodic δ-function kicks are applied with a particular strength. We use both numerical and analytical methods to study the effects of interactions in three different models in one dimension. The systems we have considered include spinless fermions with interactions between nearest-neighbor sites, the Hubbard model of spin-1/2 fermions, and the Bose Hubbard model with on-site interactions. We derive effective Floquet Hamiltonians up to second order in the time period of kicking. Using these we show that interactions can give rise to a variety of interesting results such as two-body bound states in all three models and dispersionless few-particle bound states with more than two particles for spinless fermions and bosons. We substantiate these results by exact diagonalization and stroboscopic time evolution of systems with a few particles.We derive a pseudo-spin-1/2 limit of the Bose Hubbard system in the thermodynamic limit and show that a special case of this has an exponentially large number of degenerate eigenstates of the effective Hamiltonian. Finally we study the effect of changing the strength of the δ-function kicks slightly away from perfect dynamical localization; we find that a single particle remains dynamically localized for a long time after which it moves ballistically.

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Radiation effects on the electronic properties of bilayer graphene

Cited by 128 publications

References 47 publications

Theory of Floquet band formation and local pseudospin textures in pump-probe photoemission of graphene

Theory of Floquet band formation and local pseudospin textures in pump-probe photoemission of graphene

Floquet Weyl semimetal induced by off-resonant light

Effects of interactions on periodically driven dynamically localized systems

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