Type-II Topological Dirac Semimetals: Theory and Materials Prediction (VAl3 family)

Chang, Tay-Rong; Xu, Su-Yang; Sanchez, Daniel S.; Huang, Shin-Ming; Chang, Guoqing; Hsu, Chuang‐Han; Bian, Guang; Belopolski, Ilya; Yu, Zhi‐Ming; Xu, Xicheng; Cheng, Xin; Yang, Shengyuan A.; Neupert, Titus; Jeng, Horng‐Tay; Lin, Hsin; Hasan, M. Zahid

doi:10.48550/arxiv.1606.07555

Cited by 10 publications

(13 citation statements)

References 39 publications

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“…31 Researchers are also trying to find the type-II Dirac fermions in the condensed matters. Recently, Huang et al 32 predicted that the type-II Dirac fermions protected by C 3 rotational symmetry can exist in the PtSe 2 family materials, and similar proposals were also put forward by Le et al 33 and Chang et al 34 in the KMgBi and VAl 3 family materials, respectively. Following Huang's predictions, the evidences of type-II Dirac cones in PtTe 2 , 35,36 PdTe 2 [36][37][38] and PtSe 2 36,39 were soon characterized in angle-resolved photoemission spectroscopy (ARPES) experiments by different groups.…”

Section: Introductionmentioning

confidence: 71%

“…Novel physical properties different from those in the standard type-I Dirac semimetals are expected in the type-II Dirac semimetals. 32,34 Interestingly, PdTe 2 is also a superconductor with transition temperature (T C ) about 1.7-2.0 K. 37,40,41 The coexistence of superconductivity and type-II Dirac points in PdTe 2 makes it significantly different from other members of PtSe 2 family materials, which could provide a possible platform to explore the interplay between superconducting quasi-particles and Dirac fermions. [36][37][38] Pressure can drive the topological phase transitions in the topological materials and can also assist to comprehend the nature of topological states at ambient pres- sure.…”

Section: Introductionmentioning

confidence: 99%

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Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Xiao

Gong

et al. 2017

Phys. Rev. B

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A pair of type-II Dirac cones in PdTe2 was recently predicted by theories and confirmed in experiments, making PdTe2 the first material that processes both superconductivity and type-II Dirac fermions. In this work, we study the evolution of Dirac cones in PdTe2 under hydrostatic pressure by the first-principles calculations. Our results show that the pair of type-II Dirac points disappears at 6.1 GPa. Interestingly, a new pair of type-I Dirac points from the same two bands emerges at 4.7 GPa. Due to the distinctive band structures compared with those of PtSe2 and PtTe2, the two types of Dirac points can coexist in PdTe2 under proper pressure (4.7-6.1 GPa). The emergence of type-I Dirac cones and the disappearance of type-II Dirac ones are attributed to the increase/decrease of the energy of the states at Γ and A point, which have the anti-bonding/bonding characters of interlayer Te-Te atoms. On the other hand, we find that the superconductivity of PdTe2 slightly decreases with pressure. The pressure-induced different types of Dirac cones combined with superconductivity may open a promising way to investigate the complex interactions between Dirac fermions and superconducting quasi-particles.

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Section: Introductionmentioning

confidence: 71%

Section: Introductionmentioning

confidence: 99%

Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Xiao

Gong

et al. 2017

Phys. Rev. B

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“…Nonetheless, we note that topological surface states pinned to the Dirac point have recently been reported in calculations for other type-II bulk Dirac systems. 39 The origin of the states observed here therefore requires further investigation. Irrespective, the experimental observation of an additional spin-polarised surface state here stands as a further example of the rich surface electronic structure that this compound possesses, driven by an intricate array of band inversions within the p-orbital manifold of its bulk electronic structure.…”

Section: 6mentioning

confidence: 90%

Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides

et al. 2017

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Transition-metal dichalcogenides (TMDs) are renowned for their rich and varied bulk properties, while their single-layer variants have become one of the most prominent examples of two-dimensional materials beyond graphene. Their disparate ground states largely depend on transition metal d-electron-derived electronic states, on which the vast majority of attention has been concentrated to date. Here, we focus on the chalcogen-derived states. From density-functional theory calculations together with spin-and angle-resolved photoemission, we find that these generically host a coexistence of type-I and type-II three-dimensional bulk Dirac fermions as well as ladders of topological surface states and surface resonances. We demonstrate how these naturally arise within a single p-orbital manifold as a general consequence of a trigonal crystal field, and as such can be expected across a large number of compounds. Already, we demonstrate their existence in six separate TMDs, opening routes to tune, and ultimately exploit, their topological physics.The classification of electronic structures based on their topological properties has opened powerful routes for understanding solid state materials. 1 The nowfamiliar Z 2 topological insulators are most renowned for their spin-polarised Dirac surface states residing in inverted bulk band gaps. 1 In systems with rotational invariance, a band inversion on the rotation axis can generate protected Dirac cones with a point-like Fermi surface of the bulk electronic structure. 2-8 If either inversion or time-reversal symmetry is broken, a bulk Dirac point can split into a pair of spin-polarised Weyl points. 9-15 Unlike for elementary particles, Lorentz-violating Weyl fermions can also exist in the solid state, manifested as a tilting of the Weyl cone. If this tilt is sufficiently large, so-called type-II Weyl points can occur, now formed at the touching of open electron and hole pockets. [15][16][17][18][19][20][21][22] Realising such phases in solid-state materials not only offers unique environments and opportunities for studying the fundamental properties of fermions, but also holds potential for applications exploiting their exotic surface excitations and bulk electric and thermal transport properties. [23][24][25][26][27] Consequently, there is an intense current effort focused on identifying compounds which host the requisite band inversions. In many cases, however, this arXiv:1702.08177v2 [cond-mat.mtrl-sci]

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“…The surface states of a TDS are also characterized by Fermi arcs, but the condition is more complicated than the case of a TWS 43 . Depending on the band dispersion, TDSs can be classified into type-I and type-II similarly 44,45 . Furthermore, TWS phases can usually be realized, if the TRS or IS is broken in a TDS 21,22 .…”

Section: Basic Concept Of Topological Invariantsmentioning

confidence: 99%

Topological critical materials of ternary compounds

Qin

et al. 2019

Journal of Physics and Chemistry of Solids

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We review topological properties of two series of ternary compounds AMgBi (A=K, RB, Cs) and ABC with a hexagonal ZrBeSi type structure. The first series of materials AMgBi are predicted to be topological critical Dirac semimetals. The second series of ternary compounds, such as KZnP, BaAgAs, NaAuTe and KHgSb, can be used to realize various topological insulating states and semimetal states. The states are highly tunable as the realization of these topological states depends on the competition between several energy scales, including the energy of atomic orbitals, the energy of crystal splitting, the energy difference between bonding and antibonding states, and the strength of spin-orbit coupling. The exotic surface states in these series of compounds are predicted and are closely related to their unique crystal structures.

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Type-II Topological Dirac Semimetals: Theory and Materials Prediction (VAl3 family)

Cited by 10 publications

References 39 publications

Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

Ubiquitous formation of bulk Dirac cones and topological surface states from a single orbital manifold in transition-metal dichalcogenides

Topological critical materials of ternary compounds

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