Optically induced flat bands in twisted bilayer graphene

Katz, Or; Refael, Gil; Lindner, Netanel H.

doi:10.1103/physrevb.102.155123

Cited by 51 publications

(37 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…where the superscripts refer to the type of stacking we have which can be AA, AB, or BA stacking. We choose the following tunneling parameters w 1 = 110 meV and w 0 ≈ 0.8w 1 so that they are close to those in twisted bilayer graphene where distortions in a relaxed lattice can be modelled this way [69,70], which is expected to happen for twisted trilayer graphene if we neglect next nearest layer interactions.…”

Section: Setup Of Equilibrium Model and Equilibrium Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Floquet engineering and non-equilibrium topological maps in twisted trilayer graphene

Assi,

LeBlanc,

Rodriguez-Vega

et al. 2021

Preprint

View full text Add to dashboard Cite

Motivated by the recent experimental realization of twisted trilayer graphene and the observed superconductivity that is associated with its flat bands at specific angles, we study trilayer graphene under the influence of different forms of light in the non-interacting limit. Specifically, we study four different types of stacking configurations with a single twisted layer. In all four cases, we study the impact of circularly polarized light and longitudinal light coming from a waveguide. We derive effective time-independent Floquet Hamiltonians and review light-induced changes to the band structure. For circularly polarized light, we find band flattening effects as well as band gap openings. We emphasize that there is as rich band topology, which we summarize in Chern number maps that are different for all four studied lattice configurations. The case of a so-called ABC stacked top layer twist is especially rich and shows a different phase diagram depending on the handedness of the circularly polarized light. Consequently, we propose an experiment where this difference in typologies could be captured via optical conductivity measurements. In contrast for the case of longitudinal light that is coming from a waveguide, we find that the band structure is very closely related to the equilibrium one but the magic angles can be tuned in-situ by varying the intensity of the incident beam of light.

show abstract

Section: Setup Of Equilibrium Model and Equilibrium Resultsmentioning

confidence: 99%

“…More recently, both moiré and Floquet approaches have been combined, and a wealth of additional features such as modified band structures, light induced flat bands [69][70][71] and various topological phases have been theoretically predicted [72][73][74][75][76].…”

Section: Introductionmentioning

confidence: 99%

Floquet engineering and non-equilibrium topological maps in twisted trilayer graphene

Assi,

LeBlanc,

Rodriguez-Vega

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…Application of strong time-modulated fields, and Floquet engineering methods in particular, provides exquisite control over properties of materials. These methods have been widely applied in various disciplines in condensed matter and atomic physics, enabling control over the topology and band structure of materials (34,35), the formation of time crystals (36), and modification of the effective gyromagnetic ratio of atoms and their response to external fields (37,38). Utilization of Floquet fields have long enabled to enhance the sensitivity of NMR sensors at high frequencies (39), and recently, it was proposed as an eminent avenue to enhance the performance of DM field detectors (40).…”

Section: Introductionmentioning

confidence: 99%

New constraints on axion-like dark matter using a Floquet quantum detector

et al. 2022

Self Cite

View full text Add to dashboard Cite

Dark matter is one of the greatest mysteries in physics. It interacts via gravity and composes most of our universe, but its elementary composition is unknown. We search for nongravitational interactions of axion-like dark matter with atomic spins using a precision quantum detector. The detector is composed of spin-polarized xenon gas that can coherently interact with a background dark matter field as it traverses through the galactic dark matter halo. Conducting a 5-month-long search, we report on the first results of the Noble and Alkali Spin Detectors for Ultralight Coherent darK matter (NASDUCK) collaboration. We limit ALP-neutron interactions in the mass range of 4 × 10 −15 to 4 × 10 −12 eV/ c 2 and improve upon previous terrestrial bounds by up to 1000-fold for masses above 4 × 10 −13 eV/ c 2 . We also set bounds on pseudoscalar dark matter models with quadratic coupling.

show abstract

“…The quenching of the kinetic energy of flatband electrons might allow one to reach the regime of strong LMC more easily than in strongly dispersive materials [40]. Specifically for TBG and other moiré systems, there have been first theoretical explorations of Floquet engineering [129][130][131][132][133][134][135][136][137] and nonlinear optical responses [138]. Recently a measured strong mid-infrared photoresponse in bilayer graphene at small twist angles was reported [139].…”

Section: Introductionmentioning

confidence: 99%

Light-matter coupling and quantum geometry in moiré materials

et al. 2021

View full text Add to dashboard Cite

Quantum geometry has been identified as an important ingredient for the physics of quantum materials and especially of flat-band systems, such as moiré materials. On the other hand, the coupling between light and matter is of key importance across disciplines and especially for Floquet and cavity engineering of solids. Here we present fundamental relations between light-matter coupling and quantum geometry of Bloch wave functions, with a particular focus on flat-band and moiré materials, in which the quenching of the electronic kinetic energy could allow one to reach the limit of strong light-matter coupling more easily than in highly dispersive systems. We show that, despite the fact that flat bands have vanishing band velocities and curvatures, light couples to them via geometric contributions. Specifically, the intraband quantum metric allows diamagnetic coupling inside a flat band; the interband Berry connection governs dipole matrix elements between flat and dispersive bands. We illustrate these effects in two representative model systems: (i) a sawtooth quantum chain with a single flat band and (ii) a tight-binding model for twisted bilayer graphene. For (i) we highlight the importance of quantum geometry by demonstrating a nonvanishing diamagnetic light-matter coupling inside the flat band. For (ii) we explore the twist-angle dependence of various light-matter coupling matrix elements. Furthermore, at the magic angle corresponding to almost flat bands, we show a Floquet-topological gap opening under irradiation with circularly polarized light despite the nearly vanishing Fermi velocity. We discuss how these findings provide fundamental design principles and tools for light-matter-coupling-based control of emergent electronic properties in flat-band and moiré materials.

show abstract

Optically induced flat bands in twisted bilayer graphene

Cited by 51 publications

References 58 publications

Floquet engineering and non-equilibrium topological maps in twisted trilayer graphene

Floquet engineering and non-equilibrium topological maps in twisted trilayer graphene

New constraints on axion-like dark matter using a Floquet quantum detector

Light-matter coupling and quantum geometry in moiré materials

Contact Info

Product

Resources

About