Coexistence of topological nodal lines, Weyl points, and triply degenerate points in TaS

Sun, Jianpeng; Zhang, Dong; Chang, Kai

doi:10.1103/physrevb.96.045121

Cited by 41 publications

(27 citation statements)

References 60 publications

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“…Different from rich topological states with one particular type of fermions, coexistence of distinct classes of topological fermions in a single material has rarely been proposed. Only two cases have been reported: i) coexisting triply degenerate nodal point and Weyl point in ZrTe [25]; ii) coexisting triply degenerate nodal point and nodal ring in TaS and XB2 (X = Sc, Ti, V, Zr, Hf, Nb, Ta) [26,27]. Due to distinct intriguing properties of type-I and type-II fermions, their coexistence has the potential to produce new topological phenomena, which remains to be explored in real materials.…”

Section: / 15mentioning

confidence: 99%

Engineering Dirac states in graphene: Coexisting type-I and type-II Floquet-Dirac fermions

2019

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The coupling of monochromatic light fields and solids introduces nonequilibrium Floquet states, offering opportunities to create and explore new topological phenomena. Using combined first-principles and Floquet analysis we show that one can freely engineer Floquet-Dirac fermions (FDFs) in graphene by tuning the frequency and intensity of linearly polarized light. Not only type-II FDFs are created, but they also coexist with type-I FDFs near the Fermi level. Intriguingly, novel topologically nontrivial edge states connecting type-I and type-II Floquet-Dirac points emerge in photodriven graphene, providing an ideal channel to realize electron transport between the two types of Dirac states. Simulating timeand angle-resolved photoelectron spectroscopy suggests that the new coexisting state of type-I and type-II fermions is experimentally accessible. This work implies that a rich FDF phenomenon can be engineered in atomically thin graphene, hinting for developments of novel optoelectronic and quantum computing devices.

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Section: / 15mentioning

confidence: 99%

Engineering Dirac states in graphene: Coexisting type-I and type-II Floquet-Dirac fermions

2019

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“…The type-II TNPs locate at three high-symmetry lines and are protected by the C 4v point group symmetry. TNPs have been predicted in many materials [18][19][20]22,44 . However, type-II TNP semimetal is rare 14 .…”

Section: Introductionmentioning

confidence: 99%

From Type-II Triply Degenerate Nodal Points and Three-Band Nodal Rings to Type-II Dirac Points in Centrosymmetric Zirconium Oxide

Zhang

Guo

et al. 2017

J. Phys. Chem. Lett.

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Using first-principles calculations, we report that ZrO is a topological material with the coexistence of three pairs of type-II triply degenerate nodal points (TNPs) and three nodal rings (NRs), when spin-orbit coupling (SOC) is ignored. Noticeably, the TNPs reside around the Fermi energy with a large linear energy range along the tilt direction (>1 eV), and the NRs are formed by three strongly entangled bands. Under symmetry-preserving strain, each NR would evolve into four droplet-shaped NRs before fading away, producing distinct evolution compared with that in usual two-band NR. When SOC is included, TNPs would transform into type-II Dirac points while all of the NRs are gapped. Remarkably, the type-II Dirac points inherit the advantages of TNPs: residing around the Fermi energy and exhibiting a large linear energy range. Both features facilitate the observation of interesting phenomena induced by type-II dispersion. The symmetry protections and low-energy Hamiltonian for the nontrivial band crossings are discussed.

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“…Some novel nodal point materials with three-fold, six-fold, and eight-fold degenerated band crossings have also been predicted. Significant efforts have been devoted to the prediction of nodal-point materials that can feature three-fold [ 21 , 22 , 23 , 24 , 25 ], six-fold [ 26 , 27 ], and eight-fold degenerated [ 28 ] band crossings.…”

Section: Introductionmentioning

confidence: 99%

Perfect Topological Metal CrB2: A One-Dimensional (1D) Nodal Line, a Zero-Dimensional (0D) Triply Degenerate Point, and a Large Linear Energy Range

Xia

Khenata

et al. 2020

Materials

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Topological materials with band-crossing points exhibit interesting electronic characteristics and have special applications in electronic devices. However, to further facilitate the experimental detection of the signatures of these band crossings, topological materials with a large linear energy range around the band-crossing points need to be found, which is challenging. Here, via first-principle approaches, we report that the previously prepared P6/mmm-type CrB2 material is a topological metal with one pair of 1D band-crossing points, that is, nodal lines, in the kz= 0 plane, and one pair of 0D band-crossing points, that is, triple points, along the A–Γ–A’ paths. Remarkably, around these band-crossing points, a large linear energy range (larger than 1 eV) was found and the value was much larger than that found in previously studied materials with a similar linear crossing. The pair of nodal lines showed obvious surface states, which show promise for experimental detection. The effect of the spin–orbit coupling on the band-crossing points was examined and the gaps induced by spin–orbit coupling were found to be up to 69 meV. This material was shown to be phase stable in theory and was synthesized in experiments, and is therefore a potential material for use in investigating nodal lines and triple points.

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Coexistence of topological nodal lines, Weyl points, and triply degenerate points in TaS

Cited by 41 publications

References 60 publications

Engineering Dirac states in graphene: Coexisting type-I and type-II Floquet-Dirac fermions

Engineering Dirac states in graphene: Coexisting type-I and type-II Floquet-Dirac fermions

From Type-II Triply Degenerate Nodal Points and Three-Band Nodal Rings to Type-II Dirac Points in Centrosymmetric Zirconium Oxide

Perfect Topological Metal CrB2: A One-Dimensional (1D) Nodal Line, a Zero-Dimensional (0D) Triply Degenerate Point, and a Large Linear Energy Range

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