Hybrid Weyl semimetal

Li, Fei Ye; Luo, Xi; Dai, Xi; Yu, Yue; Zhang, Fan; Chen, Gang

doi:10.1103/physrevb.94.121105

Cited by 65 publications

(57 citation statements)

References 23 publications

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“…25,27 It is identified as an intermediate state between Weyl and Dirac TSM, bringing in new interesting physics. However, there have been quite few reports on TEMs 4 discovered in oxide materials till now 12,[30][31][32][33][34] and their properties are to be extensively explored once they are available experimentally.…”

Section: Introductionmentioning

confidence: 99%

Topological phases in pyrochlore thallium niobate Tl2Nb2O6+x

et al. 2019

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The discovery of new topological electronic materials brings a chance to uncover novel physics and plays a key role in observing and controlling various intriguing phenomena. Up to now, many materials have been theoretically proposed and experimentally proved to host different kinds of topological states. Unfortunately, there is little convincing experimental evidence for the existence of topological oxides. The reason is that oxidation of oxygen leads to ionic crystal in general and makes band inversion unlikely. In addition, the realization of different topological states in a single material is quite difficult, but strongly needed for exploring topological phase transitions. In this work, using first-principles calculations and symmetry analysis, we propose that the experimentally tunable continuous solid solution of oxygen in pyrochlore Tl2Nb2O6+x (0 ≤ x ≤ 1.0) leads to various topological states. Topological insulator, Dirac semimetal and triply degenerate nodal point semimetal can be realized in it via changing the oxygen content and/or tuning the crystalline symmetries. When x = 1, it is a semimetal with quadratic band touching point at Fermi level. It transits into a Dirac semimetal or a topological insulator depending on the in-plane strain. When x = 0.5, the inversion symmetry is spontaneously broken in Tl2Nb2O6.5, leading to triply degenerate nodal points. When x = 0, Tl2Nb2O6 becomes a trivial insulator with a narrow band gap. These topological phase transitions driven by solid solution of oxygen are unique and physically plausible due to the variation of valence state of Tl 1+ and Tl 3+ . This topological oxide will be promising for studying correlation induced topological states and potential applications.

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Section: Introductionmentioning

confidence: 99%

Topological phases in pyrochlore thallium niobate Tl2Nb2O6+x

et al. 2019

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“…In figure 6, we also give numerical results with different tilting strengths C. There are two flat bands near the nodal line when C 1 < | | , which corresponds to the zeroth Landau level. When C 1 > | | , the flat bands disappear, and the system becomes metal which is similar to WSMs [19][20][21].…”

Section: Effect Of Magnetic Field On Type-ii Nlsmsmentioning

confidence: 85%

“…In addition, new types of WSMs are proposed which are called type-II WSM [19] and Hybrid (type-1.5) WSM [20,21]. In these types of WSMs, Lorentz invariance of low-energy excitations is broken.…”

Section: Introductionmentioning

confidence: 99%

Type-II nodal line semimetal

Kong

Wang

et al. 2018

New J. Phys.

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Recently, topological semimetals have become a hot topic in condensed matter physics, including Dirac semimetals, Weyl semimetals, and nodal line semimetals (NLSMs). In this paper, a new type of NLSM-type-II NLSM-is proposed based on a two-band cubic lattice model. For type-II NLSM, the zero energy bulk states have a closed loop in momentum space but the (local) Weyl cones on the nodal line become tilted. The effect of the magnetic field and that of the correlation on type-II NLSM are studied. In particular, after considering the repulsive interaction and additional spin degrees of freedom, different types of long range magnetic orders appear in bulk states. In addition, the interaction-induced ferromagnetic (FM) order of surface states may exist. At a critical point between type-I NLSM and type-II NLSM, arbitrary tiny interactions induce FM order due to a flat band at the Fermi surface.

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“…In this subsection, we obtain the boundary of the magnetic transition using HF mean field theory. A spin density wave (SDW) phase can emerge in various Hubbard models on the honeycomb lattice, regardless of whether there is a topological band structure or not [20,42,43,45,46]. In our KMH model, the topologically non-trivial band structure of the spin degree of freedom should be destroyed due to the breaking of time-reversal symmetries with the development of magnetic order.…”

Section: The Magnetic Transitionmentioning

confidence: 99%

Phase transitions of the Kane–Mele–Hubbard model with a long-range hopping

Li²,

Lu³

et al. 2018

J. Phys.: Condens. Matter

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The interacting Kane-Mele model with a long-range hopping is studied using analytical method. The original Kane-Mele model is defined on a honeycomb lattice. In the work, we introduce a four-lattice-constant range hopping and the on-site Hubbard interaction into the model and keep its lattice structure unchanged. From the single-particle energy spectrum, we obtain the critical strength of the long-range hopping t L at which the topological transition occurs in the non-interacting limit of the model and our results show that it is independent of the spin-orbit coupling. After introducing the Hubbard interaction, we investigate the Mott transition and the magnetic transition of the generalized strongly correlated Kane-Mele model using the slave-rotor mean field theory and Hartree-Fock mean field theory respectively. In the small long-range hopping region, it is a correlated quantum spin Hall state below the Mott transition, while a topological Mott insulator above the Mott transition. By comparing the energy band of spin degree of freedom with the one of electrons in non-interacting limit, we find a condition for the t L -driven topological transition. Under the condition, critical values of t L at which the topological transition occurs are obtain numerically from seven self-consistency equations in both regions below and above the Mott transition. Influences of the interaction and the spin-orbit coupling on the topological transition are discussed in this work. Finally, we show complete phase diagrams of the generalized interacting topological model at some strength of spin-orbital coupling.Phase transitions of the Kane-Mele-Hubbard model with a long-range hopping

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Hybrid Weyl semimetal

Cited by 65 publications

References 23 publications

Topological phases in pyrochlore thallium niobate Tl2Nb2O6+x

Topological phases in pyrochlore thallium niobate Tl2Nb2O6+x

Type-II nodal line semimetal

Phase transitions of the Kane–Mele–Hubbard model with a long-range hopping

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