Three-dimensional honeycomb carbon: Junction line distortion and novel emergent fermions

Hu, Junping; Wu, Weikang; Zhong, Chengyong; Liu, Ning; Ouyang, Chuying; Yang, Hui; Yang, Shengyuan A.

doi:10.1016/j.carbon.2018.09.027

Cited by 50 publications

(41 citation statements)

References 81 publications

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“…We confirmed the existence of the energy minimum as a function of the volume, which suggests that (2,2)-Hopfene is thermodynamically stable. The calculated energy and the curve are similar to those calculated for Graphite and diamonds [57]. We admit that simple energetic calculations are not sufficient enough to prove the existence of Hopfene as a stable material.…”

Section: Topological Crystal: Hopfene (3d )supporting

confidence: 63%

Topological carbon allotropes: knotted molecules, carbon-nano-chain, chainmails, and Hopfene

Saito

Tomita

2020

Mater. Res. Express

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Carbon allotropes such as diamond, nano-tube, Fullerene, and Graphene were discovered and revolutionised material sciences. These structures have unique translational and rotational symmetries, described by a crystallographic group theory, and the atoms are arranged at specific rigid positions in 3-dimensional (D) space. Regardless of these exotic molecular structures, the structures of materials are topologically trivial in a mathematical sense, that their bonds are connected without a link nor a knot. These days, the progress on the synthetic chemistry is significant to make various topologically non-trivial molecular structures. Topological molecules (0D) including Trefoil knots, a Hopf-link, a Möbius strip, and Borromean rings, were already realised. However, their potentially exotic electronic properties have not been sufficiently explored. Here, we propose a new 3D carbon allotrope, named Hopfene, which has periodic arrays of Hopf-links to knit horizontal Graphene sheets into vertical ones without connecting by σ bonds. We conducted an ab inito band structure calculation using a Density-Functional-Theory (DFT) for Hopfene, and found that it is well-described by a tightbinding model. We confirmed the original Dirac points of 2D Graphene were topologically protected upon the introduction of the Hopf links, and low-energy excitations are described by 1D, 2D, and 3D gapless Fermions.

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Section: Topological Crystal: Hopfene (3d )supporting

confidence: 63%

Topological carbon allotropes: knotted molecules, carbon-nano-chain, chainmails, and Hopfene

Saito

Tomita

2020

Mater. Res. Express

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“…This finding indicated that the phase of BNHC structure was changed at about 4500 K and it began to melt. The obtained melting point of BNHCs by MD simulations was around 4500 K. It is found that CHCs maintains structural stability at 2000 K [31], which confirmed the high thermal stability of BNHCs.…”

Section: Resultsmentioning

confidence: 78%

Molecular Dynamics Simulation on Mechanical and Piezoelectric Properties of Boron Nitride Honeycomb Structures

Xie

Wang

et al. 2019

Nanomaterials

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Boron nitride honeycomb structure is a new three-dimensional material similar to carbon honeycomb, which has attracted a great deal of attention due to its special structure and properties. In this paper, the tensile mechanical properties of boron nitride honeycomb structures in the zigzag, armchair and axial directions are studied at room temperature by using molecular dynamics simulations. Effects of temperature and strain rate on mechanical properties are also discussed. According to the observed tensile mechanical properties, the piezoelectric effect in the zigzag direction was analyzed for boron nitride honeycomb structures. The obtained results showed that the failure strains of boron nitride honeycomb structures under tensile loading were up to 0.83, 0.78 and 0.55 in the armchair, zigzag and axial directions, respectively, at room temperature. These findings indicated that boron nitride honeycomb structures have excellent ductility at room temperature. Moreover, temperature had a significant effect on the mechanical and tensile mechanical properties of boron nitride honeycomb structures, which can be improved by lowering the temperature within a certain range. In addition, strain rate affected the maximum tensile strength and failure strain of boron nitride honeycomb structures. Furthermore, due to the unique polarization of boron nitride honeycomb structures, they possessed an excellent piezoelectric effect. The piezoelectric coefficient e obtained from molecular dynamics was 0.702 C / m 2 , which was lower than that of the monolayer boron nitride honeycomb structures, e = 0.79 C / m 2 . Such excellent piezoelectric properties and failure strain detected in boron nitride honeycomb structures suggest a broad prospect for the application of these new materials in novel nanodevices with ultrahigh tensile mechanical properties and ultralight-weight materials.

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“…In this way, the Weyl and Dirac semimetals were discovered [5][6][7][8][9][10][11], which have twofold and fourfold degenerate band crossing points, and around these points, the low-energy electrons resemble the Weyl and Dirac fermions and can exhibit fascinating physical effects like their counterparts in high energy physics [12][13][14]. Moving forward, it was realized that crystalline solids may host more types of emergent fermions beyond the Weyl/Dirac paradigm [15][16][17][18][19]. For example, in a three-dimensional (3D) material, besides 0D nodal point, band crossings may also take the form of 1D nodal loops [20][21][22][23][24][25][26][27][28][29] or even 2D nodal surfaces [30][31][32][33][34].…”

Section: Introductionmentioning

confidence: 99%

Hourglass Weyl loops in two dimensions: Theory and material realization in monolayer GaTeI family

Jiao

et al. 2019

Phys. Rev. Materials

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Nodal loops in two-dimensional (2D) systems are typically vulnerable against spin-orbit coupling (SOC). Here, we explore 2D systems with a type of doubly degenerate nodal loops that are robust under SOC and feature an hourglass type dispersion. We present symmetry conditions for realizing such hourglass Weyl loops, which involve nonsymmorphic lattice symmetries. Depending on the symmetry, the loops may exhibit different patterns in the Brillouin zone. Based on first-principles calculations, we identify the monolayer GaTeI-family materials as a realistic material platform to realize such loops. These materials host a single hourglass Weyl loop circling around a high-symmetry point. Interestingly, there is also a spin-orbit Dirac point enabled by an additional screw axis. We show that the hourglass Weyl loop and the Dirac point are robust under a variety of applied strains. By breaking the screw axis, the Dirac point can be transformed into a second Weyl loop. Furthermore, by breaking the glide mirror, the hourglass Weyl loop and the spin-orbit Dirac point can both be transformed into a pair of spin-orbit Weyl points. Our work offers guidance and realistic material candidates for exploring fascinating physics of several novel 2D emergent fermions. arXiv:1902.09283v2 [cond-mat.mtrl-sci]

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Three-dimensional honeycomb carbon: Junction line distortion and novel emergent fermions

Cited by 50 publications

References 81 publications

Topological carbon allotropes: knotted molecules, carbon-nano-chain, chainmails, and Hopfene

Topological carbon allotropes: knotted molecules, carbon-nano-chain, chainmails, and Hopfene

Molecular Dynamics Simulation on Mechanical and Piezoelectric Properties of Boron Nitride Honeycomb Structures

Hourglass Weyl loops in two dimensions: Theory and material realization in monolayer GaTeI family

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