A charge-density-wave topological semimetal

Shi, Wujun; Wieder, Benjamin J.; Meyerheim, H. L.; Sun, Yan; Zhang, Yang; Li, Yiwei; Shen, Lei; Qi, Yue; Yang, Lexian; Jena, Jagannath; Werner, P.; Koepernik, Klaus; Parkin, Stuart S. P.; Chen, Yulin; Felser, Claudia; Bernevig, B. Andrei; Wang, Zhijun

doi:10.1038/s41567-020-01104-z

Cited by 107 publications

(106 citation statements)

References 58 publications

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“…In correlated systems, interactions might make it possible to open a global gap in the system with Weyl fermions. For instance, it has been reported that a Weyl semimetal can be gapped out into an axion insulator by the charge-density-wave (CDW) pairing interaction [22][23][24][25], although the general mechanism of this metal-insulator transition remains elusive.…”

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confidence: 99%

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Relativistic horizon of interacting Weyl fermions in condensed matter systems

Chiu¹,

Chang²,

Macam³

et al. 2022

Preprint

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The intersections of topology, geometry and strong correlations offer many opportunities for exotic quantum phases to emerge in condensed matter systems. Weyl fermions, in particular, provide an ideal platform for exploring the dynamical instabilities of single-particle physics under interactions. Despite its fundamental role in relativistic field theory, the concept of causality and the associated spacetime light cone and event horizon has not been considered in connection with interacting Weyl fermionic excitations in quantum matter. Here, by using charge-density wave (CDW) as an example, we unveil the behavior of interacting Weyl fermions and show that a Weyl fermion in a system can open a band gap by interacting only with other Weyl fermions that lie within its energy-momentum dispersion cone. In this sense, causal connections or interactions are only possible within overlapping dispersion cones and each dispersion cone thus constitutes a solid-state analogue of the more conventional 'event horizon' of high-energy physics. Our study provides a universal framework for considering interacting relativistic quasiparticles in condensed matter by separating them into energy-like and momentum-like relationships in analogy with the time-like and space-like events in high-energy physics. Finally, we consider two different candidate materials for hosting the Weyl CDW phase: (TaSe 4 ) 2 I and Mo 3 Al 2 C. Our study greatly enriches the phenomenology and unveils new connections between condensed matter and high-energy physics.

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confidence: 99%

“…In this work, we discuss the general case of a CDW in a three-dimensional Weyl semimetal (Fig. 1b), which is much more representative of real materials [22,23], where the energy difference between the Weyl nodes and the momentum mismatch between the CDW Q-vector, along with the separation between the correlated Weyl nodes are all taken into account.…”

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confidence: 99%

Relativistic horizon of interacting Weyl fermions in condensed matter systems

Chiu¹,

Chang²,

Macam³

et al. 2022

Preprint

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“…The family of linear-chain compounds (M Se 4 ) n I where M =Nb and Ta and n=2, 3, and 10/3, have attracted the attention of the community time and again because they display wide varieties of phase transitions and phase co-existences [1][2][3][4][21][22][23][24][25]. In this family of compounds, the MSe 4 chains, which are separated from each other by the iodine atoms, run along the c axis thereby giving rise to quasi-one-dimensional structure [1][2][3][4].…”

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confidence: 99%

“…Recently, a member of the (MSe 4 ) n I family with n = 2, (TaSe 4 ) 2 I, was shown to host an exotic axionic CDW phase [21,22]. However, for n =3, (NbSe 4 ) 3 I and (TaSe 4 ) 3 I are known to form a centrosymmetric structure with space group P 4/mnc [2].…”

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confidence: 99%

“…Furthermore, the linear nature of the R vs. T 2 plot (in the lower inset) in the temperature range of 5-25 K confirms that n-TSI is a clean Fermi liquid metal. R(T ) curve shows a slope change around 150 K which is known to arise for a charge density wave (CDW) transition due to Peierls-like instability of the linear chain structure [1,2,[21][22][23][24][25]. Below 2.5 K, the resistance shows a sharp fall which resembles a superconducting transition.…”

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Superconductivity coexisting with ferromagnetism in a quasi-one dimensional non-centrosymmetric (TaSe4)3I

Bera¹,

Gayen

Mondal

et al. 2021

Preprint

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Low-dimensional materials with broken inversion symmetry and strong spin-orbit coupling can give rise to fascinating quantum phases and phase transitions. Here we report coexistence of superconductivity and ferromagnetism below 2.5 K in the quasione dimensional crystals of non-centrosymmetric (TaSe4)3I (space group: P¯421c). The unique phase is a direct consequence of inversion symmetry breaking as the same material also stabilizes in a centro-symmetric structure (space group: P4/mnc) where it behaves like a non-magnetic insulator[1–4]. The coexistence here upfront contradicts the popular belief that superconductivity and ferromagnetism are two apparently antagonistic phenomena. Notably, here, for the first time, we have clearly detected Meissner effect in the superconducting state despite the coexisting ferromagnetic order. The coexistence of superconductivity and ferromagnetism projects non-centrosymmetric (TaSe4)3I as a host for complex ground states of quantum matter including possible unconventional superconductivity with elusive spin-triplet pairing[5–8].

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Realization of Coexisting Charge Density Wave and Quantum Spin/Anomalous Hall State in Monolayer NbTe₂

Zhang

Zou

Ren

et al. 2022

Adv Funct Materials

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The combination of nontrivial topology and charge density wave (CDW) has been proposed as a powerful resource for realizing novel quantum phenomena such as axion electrodynamics and the anomalous Hall effect. Hence, topological materials with CDW states attract great interest, yet they are still very rare, particularly in the 2D limit. Here, it is predicted that monolayer NbTe 2 in its high-symmetry 1T phase stabilized by anharmonicity at room temperature exhibits nontrivial topology sensitive to electronic interactions: it changes from a quantum spin Hall (QSH) state to a quantum anomalous Hall (QAH) state when the Hubbard potential U exceeds a critical value. At low temperature, a 4 × 4 CDW order emerges and coexists with the nontrivial topology. Meanwhile, the critical U increases because CDW reduces density of states at Fermi level. More interestingly, in contrast to the high-symmetry structure that actually is a topologically nontrivial metal, the CDW structure shows an insulating nontrivial gap either in the QSH or the QAH phase, indicating CDW is an effective means to modulate the topological state for developing new functions and devices. These discoveries establish NbTe 2 as a promising candidate to explore exotic quantum states at the confluence of nontrivial topology, electronic correlation, and CDW.

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A charge-density-wave topological semimetal

Cited by 107 publications

References 58 publications

Relativistic horizon of interacting Weyl fermions in condensed matter systems

Relativistic horizon of interacting Weyl fermions in condensed matter systems

Superconductivity coexisting with ferromagnetism in a quasi-one dimensional non-centrosymmetric (TaSe4)3I

Realization of Coexisting Charge Density Wave and Quantum Spin/Anomalous Hall State in Monolayer NbTe₂

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A charge-density-wave topological semimetal

Cited by 107 publications

References 58 publications

Relativistic horizon of interacting Weyl fermions in condensed matter systems

Relativistic horizon of interacting Weyl fermions in condensed matter systems

Superconductivity coexisting with ferromagnetism in a quasi-one dimensional non-centrosymmetric (TaSe4)3I

Realization of Coexisting Charge Density Wave and Quantum Spin/Anomalous Hall State in Monolayer NbTe2

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Realization of Coexisting Charge Density Wave and Quantum Spin/Anomalous Hall State in Monolayer NbTe₂