Topological Triply Degenerate Points Induced by Spin-Tensor-Momentum Couplings

Hu, Haiping; Hou, Jue; Zhang, Fan; Zhang, Chuanwei

doi:10.1103/physrevlett.120.240401

Cited by 64 publications

(47 citation statements)

References 67 publications

(131 reference statements)

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“…Note that C + = −C − for the higher and lower bands and C 0 = 0 for the middle one even if βN ij term exists, which has been numerical confirmed. Similar to the case for the linear triple-points [26], we find that there are three types of quadratic DTPs induced by the tensors N ij of different forms in Eq. (1).…”

Section: A Continuum Modelsupporting

confidence: 68%

“…A threefold degenerate point described by this effective Hamiltonian is a linear triple point [26]. Specially, the type-I DTP of C = ±4 for N ij = N zz are broken into two linear triple point with C = ±2, as shown in Fig.…”

Section: A Continuum Modelmentioning

confidence: 99%

“…Very recently, considerable attention have been paid to searching for unconventional massless fermionic excitations beyond Dirac and Weyl paradigm [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. In contrast to particles in high-energy physics constrained by Poincaré symmetry, quasiparticles in a lattice system are only constrained by certain subgroups (space groups) of the Poincaré symmetry, which allows the emergence of "new fermions" (fermionic quasiparticles beyond the Dirac-Weyl-Majorana classification) in some band structures with three-or morefold degeneracies [14].In particular, triple-point (three-component) fermions as spin-1 generalization of Weyl fermions in certain topological metal bands with threefold degeneracies were theoretically predicted and then experimental observed in some condensed matter materials [15,23].…”

Section: Introductionmentioning

confidence: 99%

“…In addition, several schemes have been suggested to realize topological semimetal bands with Weyl fermions [56][57][58][59][60][61][62][63][64][65][66] and double-Weyl fermions [67,68]. Moreover, it has been proposed that the spin-1 triplepoint fermions can emerge in some topological metal bands in cold atom systems [24][25][26], which can even be simulated in parameter space [69,70]. Due to the elusive nature of triple-point fermions in real materials and their exotic properties [14][15][16][17][18][19][20][21][22][23][24][25][26], proposals for realizing other types of triple-point fermions in artifical cold atom systems would be of great value.…”

Section: Introductionmentioning

confidence: 99%

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Topological metal bands with double-triple-point fermions in optical lattices

Mai

Zhu

et al. 2018

Phys. Rev. A

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Novel fermionic quasiparticles with integer pseudospins in some energy bands, such as pseudospin-1 triple-point fermions, recently attract increasing interest since they are beyond the conventional spin-1/2 Dirac and Weyl counterparts. In this paper, we propose a class of pseudospin-1 fermioic excitations emerging in topological metal bands, dubbed double-triple-point (DTP) fermions. We first present a general three-band continuum model with C4 symmetry in three dimensions, which has three types of threefold degenerate points in the bands classified by their topological charges C = ±4, ±2, 0, respectively. They are dubbed DTPs as spin-1 generalization of double-Weyl points. We then construct two-dimensional and three-dimensional tight-binding lattice models of topological metal bands with exotic DTP fermions near the DTPs. In two dimensions, the band gaps close at a trivial DTP with zero Berry phase, which occurs at the transition between the normal and topological insulator phases. In three dimensions, the topological properties of three different DTP fermions in lattice systems are further investigated, and the effects of breaking C4 symmetry are also studied, which generally leads to splitting each quadratic DTP into two linear triple points and gives topological phase diagrams. Using ultracold fermionic atoms in optical lattices, the proposed models can be realized and the topological properties of the DTP fermions can be detected. * Electronic address: danweizhang@m.scnu.edu.cn † Electronic address: slzhu@nju.edu.cn arXiv:1810.11560v1 [cond-mat.quant-gas]

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Section: A Continuum Modelsupporting

confidence: 68%

Section: A Continuum Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Topological metal bands with double-triple-point fermions in optical lattices

Mai

Zhu

et al. 2018

Phys. Rev. A

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“…In a topological semimetal MoP, another kind of triply degenerate fermion was observed [11]. Subsequent studies searching for the material realizations of triply degenerate fermions and their novel properties were done [12][13][14][15][16][17][18][19][20]. Among these triply degenerate fermion systems, the ferotons are of particular interest as we will see.…”

Section: Introductionmentioning

confidence: 97%

Anomalous magnetic transport and extra quantum oscillation in semi-metallic photon-like fermion gas

Luo¹,

Li²,

Yu³

2018

New J. Phys.

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In the absence of Lorentz symmetry, the pseudospin-1 counterpart of the Weyl fermion (feroton) with linear dispersions and an exact flat band can emerge in condensed matter systems. The flat band branch of the feroton is equivalent to the longitudinal photon in Maxwell theory, which is a redundant degree of freedom due to the emergent (fermionic) gauge symmetry. Upon coupling to an external magnetic field, the fermionic gauge symmetry is broken and the flat band ferotons become gapless excitations characterized by Landau level indices (n>1). In the long wavelength limit, these gapless modes are of the opposite chirality to the chiral anomaly related zero Landau level, which leads to much more plentiful magnetic transport properties. To further explore the novel properties of these gapless modes, we investigate the quantum oscillation through a generalized Lieb lattice model. We find an extra oscillating behavior which indicates the existence of these exotic gapless modes. We collect known ab initio calculation data from the literature and discuss the possibility of realizing the semi-metallic feroton gas in real materials.

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Topological Surface States in a Gyroid Acoustic Crystal

2022

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The acoustic properties of an acoustic crystal consisting of acoustic channels designed according to the gyroid minimal surface embedded in a 3D rigid material are investigated. The resulting gyroid acoustic crystal is characterized by a spin-1 Weyl and a charge-2 Dirac degenerate points that are enforced by its nonsymmorphic symmetry. The gyroid geometry and its symmetries produce multi-fold topological degeneracies that occur naturally without the need for ad hoc geometry designs. The non-trivial topology of the acoustic dispersion produces chiral surface states with open arcs, which manifest themselves as waves whose propagation is highly directional and remains confined to the surfaces of a 3D material. Experiments on an additively manufactured sample validate the predictions of surface arc states and produce negative refraction of waves at the interface between adjoining surfaces. The topological surface states in a gyroid acoustic crystal shed light on nontrivial bulk and edge physics in symmetry-based compact continuum materials, whose capabilities augment those observed in ad hoc designs. The continuous shape design of the considered acoustic channels and the ensuing anomalous acoustic performance suggest this class of phononic materials with semimetal-like topology as effective building blocks for acoustic liners and load-carrying structural components with sound proofing functionality.

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Topological Triply Degenerate Points Induced by Spin-Tensor-Momentum Couplings

Cited by 64 publications

References 67 publications

Topological metal bands with double-triple-point fermions in optical lattices

Topological metal bands with double-triple-point fermions in optical lattices

Anomalous magnetic transport and extra quantum oscillation in semi-metallic photon-like fermion gas

Topological Surface States in a Gyroid Acoustic Crystal

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