Tilted anisotropic Dirac cones in partially hydrogenated graphene

Lu, Hong‐Yan; Cuamba, Armindo S.; Lin, Shih-Yang; Hao, Lei; Wang, Rui; Li, Hai; Zhao, Youjun; Ting, C. S.

doi:10.1103/physrevb.94.195423

Cited by 55 publications

(35 citation statements)

References 62 publications

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“…For other surface terminations the Dirac cone of the SS becomes anisotropic with elliptical curves of constant energy, as reported for the (221) surface in [3]. Anisotropic Dirac fermions have interesting transport properties due to the different group velocity in different directions [4], and have attracted attention in other Dirac materials [5,6].…”

Section: Introductionmentioning

confidence: 74%

Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators

et al. 2018

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Based on group theoretical arguments we derive the most general Hamiltonian for the Bi 2 Se 3 -class of materials including terms to third order in the wave vector, first order in electric and magnetic fields, first order in strain and first order in both strain and wave vector. We determine analytically the effects of strain on the electronic structure of Bi 2 Se 3 . For the most experimentally relevant surface termination we analytically derive the surface state (SS) spectrum, revealing an anisotropic Dirac cone with elliptical constant energy contours giving rise to a direction-dependent group velocity. The spinmomentum locking of strained Bi 2 Se 3 is shown to be modified. Hence, strain control can be used to manipulate the spin degree of freedom via the spin-orbit coupling. We show that for a thin film of Bi 2 Se 3 the SS band gap induced by coupling between the opposite surfaces changes opposite to the bulk band gap under strain. Tuning the SS band gap by strain, gives new possibilities for the experimental investigation of the thickness dependent gap and optimization of optical properties relevant for, e.g., photodetector and energy harvesting applications. We finally derive analytical expressions for the effective mass tensor of the Bi 2 Se 3 class of materials as a function of strain and electric field.

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Section: Introductionmentioning

confidence: 74%

Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators

et al. 2018

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“…TDFs are also expected in purely 2D, namely oneatom-thick compounds. First principle calculations suggest that partially hydrogenated graphene compound, C 6 H 2 has a tilted Dirac cone (TDC) in its spectrum [25]. The left neighbor of Carbon in the periodic table of elements, namely, boron in 8Pmmn lattice structure is also predicted to host TDFs [26,27].…”

Section: A Materials Hosting Tilted Dirac/weyl Conesmentioning

confidence: 99%

Synthetic non-Abelian gauge fields and gravitomagnetic effects in tilted Dirac cone systems

Farajollahpour

Jafari

2020

Phys. Rev. Research

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In planar tilted Dirac cone systems, the tilt parameter can be made space-dependent by either a perpendicular displacement field or by chemical substitution in certain systems. We show that the symmetric partial derivative of the tilt parameter generates non-Abelian synthetic gauge fields in these systems. The small velocity limit of these gauge forces corresponds to Rashba and Dresselhaus spin-orbit couplings. At the classical level, new forms of forces from conservative and Lorentz-type to (anti-)friction-like forces emerge from the effective spacetime structure in these materials. The velocity-dependent forces are odd with respect to tilt and therefore have opposite signs in the two valleys when the system is inversion symmetric. Furthermore, toggling the chemical potential between the valence and conduction bands by a gate voltage reverses the sign of the all these classical forces, which indicates these forces couple to the electric charge of the carriers. As such, these "gravitomagnetic" forces are natural extensions of the electric and magnetic forces that appear in the particular geometry of the tilted Dirac cone systems.

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“…1(b)). In two dimensional materials, this kind of tilted Dirac dispersion has been predicted to appear in quinoid-type 10 and hydrogenated graphene 11 , and it has been indirectly evidenced in the organic semiconductor 10,12,13 α-(BEDT-TTF)2I3. The interest of materials presenting this dispersion resides in its non-isotropic transport properties, which can be used for valley filtering in p−n junc8ons 14 or for the generation of photocurrent 15 .…”

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confidence: 96%

Type-III and Tilted Dirac Cones Emerging from Flat Bands in Photonic Orbital Graphene

et al. 2019

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The extraordinary electronic properties of Dirac materials, the two-dimensional partners of Weyl semimetals, arise from the linear crossings in their band structure. When the dispersion around the Dirac points is tilted, the emergence of intricate transport phenomena has been predicted, such as modified Klein tunnelling, intrinsic anomalous Hall effects and ferrimagnetism. However, Dirac materials are rare, particularly with tilted Dirac cones. Recently, artificial materials whose building blocks present orbital degrees of freedom have appeared as promising candidates for the engineering of exotic Dirac dispersions. Here we take advantage of the orbital structure of photonic resonators arranged in a honeycomb lattice to implement photonic lattices with semi-Dirac, tilted and, most interestingly, type-III Dirac cones that combine flat and linear dispersions. The tilted cones emerge from the touching of a flat and a parabolic band with a non-trivial topological charge. These results open the way to the synthesis of orbital Dirac matter with unconventional transport properties and, in combination with polariton nonlinearities, to the study of topological and Dirac superfluids in photonic lattices.

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Tilted anisotropic Dirac cones in partially hydrogenated graphene

Cited by 55 publications

References 62 publications

Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators

Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators

Synthetic non-Abelian gauge fields and gravitomagnetic effects in tilted Dirac cone systems

Type-III and Tilted Dirac Cones Emerging from Flat Bands in Photonic Orbital Graphene

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Tilted anisotropic Dirac cones in partially hydrogenated graphene

Cited by 55 publications

References 62 publications

Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

Symmetry analysis of strain, electric and magnetic fields in the Bi2Se3-class of topological insulators

Synthetic non-Abelian gauge fields and gravitomagnetic effects in tilted Dirac cone systems

Type-III and Tilted Dirac Cones Emerging from Flat Bands in Photonic Orbital Graphene

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Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators

Symmetry analysis of strain, electric and magnetic fields in the Bi₂Se₃-class of topological insulators