Surface charge induced Dirac band splitting in a charge density wave material 
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Yi, Hemian; Huang, Zengle; Shi, Wujun; Min, Lujin; Wu, Rui; Polley, Craig; Zhang, Ruoxi; Zhao, Yi; Zhou, Ling-Jie; Adell, Johan; Gui, Xin; Xie, Weiwei; Chan, Moses H. W.; Mao, Zhiqiang; Wang, Zhijun; Wu, Weida; Chang, Cui Zu

doi:10.1103/physrevresearch.3.013271

Cited by 18 publications

(17 citation statements)

References 44 publications

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“…The recent first principle calculations confirms the high temperature phase of (TaSe 4 ) 2 I is indeed a Weyl semimetal, one of the necessary conditions for the axionic CDW phase [7,8]. The bulk band structure was confirmed by recent angle-resolved photoemission spectroscopy (ARPES) measurements [19]. The observation that Dirac nodes along the high symmetry line is 0.4 eV below the Fermi energy [19] agrees with previous studies [18].…”

supporting

confidence: 84%

“…The bulk band structure was confirmed by recent angle-resolved photoemission spectroscopy (ARPES) measurements [19]. The observation that Dirac nodes along the high symmetry line is 0.4 eV below the Fermi energy [19] agrees with previous studies [18]. However, significant thermal broadening at room temperature prevents high resolution spectroscopy measurements of the Fermi arc surface states, the smoking-gun evidence of Weyl semimetals [20][21][22][23][24].…”

supporting

confidence: 77%

“…There is a lack of real-space characterization such as scanning tunneling microscopy (STM) imaging of the CDW modulations in (TaSe 4 ) 2 I despite that the compound had been studied for decades [7,[10][11][12]18]. Recently, we have demonstrated the first STM imaging of the CDW phase of (TaSe 4 ) 2 I [19], which opens up the possibility of tunneling spectroscopy studies of topological defects of the CDW phase.…”

mentioning

confidence: 99%

“…The density of iodine ions on the surface determines the surface electric potential and band bending near surface. Recent ARPES measurements found that the loss of surface iodine ions due to thermal annealing introduces a substantial surface electric field that induces a Rashba-like splitting of the Dirac bands [19].…”

mentioning

confidence: 99%

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Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

Huang,

Yi,

Min

et al. 2021

Preprint

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Axion electrodynamics in condensed matter could emerge from the formation of charge density wave (CDW) in Weyl semimetals. (TaSe 4 ) 2 I was proposed to be the first material platform for realizing axionic CDW that may host topological defects with 1-dimensional in-gap modes. The real-space modulation of CDW phase and the existence of in-gap modes remain elusive. Here we present the first comprehensive scanning tunneling microscopic and spectroscopic study on the CDW on (TaSe 4 ) 2 I (110) surface. The tunneling spectroscopic measurements reveal a CDW gap of ∼ 200 meV, in good agreement with prior studies, while spectroscopy of CDW edge dislocation shows no indication of in-gap states. The bias-dependent STM images indicate that the CDW in (TaSe 4 ) 2 I is dominated by large periodic lattice distortion instead of charge modulation, suggesting a non-Peierls mechanism of the CDW instability.

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supporting

confidence: 84%

supporting

confidence: 77%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

Huang,

Yi,

Min

et al. 2021

Preprint

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“…Second, Ta 2 ISe 8 [ICSD 35190, SG 97 (I422)] in Fig. 91 is a structurally chiral, quasi-1D Weyl semimetal that, as demonstrated in recent theoretical and experimental investigations, becomes gapped by a topological (axionic) charge-density wave when cooled just below room temperature [26,27,59,[211][212][213]. Most notably, Figs.…”

Section: B Es-classified Semimetalsmentioning

confidence: 88%

All Topological Bands of All Stoichiometric Materials

Vergniory,

Wieder,

Elcoro

et al. 2021

Preprint

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The recently introduced theories of Topological Quantum Chemistry and Symmetry-Based Indicators (SIs) have facilitated the discovery of novel stable topological phases of matter and largescale searches for materials with experimentally accessible topological properties at the Fermi energy (EF ). In this work, we have completed the first catalog of stable and fragile topology in all of the bands both at and away from EF in the Inorganic Crystal Structure Database (ICSD), which we have made accessible through a substantial upgrade of Topological Materials Database (https://www.topologicalquantumchemistry.com/). We have computed the electronic structure, topological class, and stable and fragile SIs of all bands in the 96,196 processable ICSD entries with stoichiometric chemical formulas in the presence and absence of spin-orbit coupling, which we have grouped into 38,298 unique materials by common chemical formulas, crystal structures [space groups (SGs)], and topology at EF . Our calculations represent the completion of the symmetry-indicated band topology of known nonmagnetic materials, and a doubling of the number of materials accessible in previous topological material catalogs. Through our calculations, we discover the existence of novel classes of topological materials, including enforced topological semimetals with energetically isolated fragile bands at EF , repeat-topological (RTopo) materials with stable topological insulating gaps at and just below EF , and supertopological (STopo) materials in which every energetically isolated set of bands above the core shell is stable topological. Our findings recontextualize several previous experimental investigations of topological materials. We find that the transition-metal chalcogenides Ta2NiSe5 in SG 15 (C/2c) and Ta2NiSe7 in SG 12 (C2/m) -respectively previously highlighted for hosting exciton-insulator and charge-density-wave phases -are 3D topological insulators (TIs) in their normal states. Additionally, we find that the higher-order TI rhombohedral bismuth in SG 166 (R 3m) and the indirect-gap TI Bi2Mg3 in SG 164 (P 3m1) are both RTopo and STopo materials. Previous ARPES investigations of Bi2Mg3 have demonstrated the presence of "surface resonance bands" below EF -in this work, we discover that the surface resonance bands are in fact RTopo Dirac-cone surface states. We present detailed statistics for our computations revealing that 52.65% of all materials are topological at EF , roughly 2/3 of bands across all materials exhibit symmetry-indicated stable topology, and that, shockingly, 87.99% of all materials contain at least one stable or fragile (crystalline) topological band in their spectrum (though potentially far from EF ). Our findings motivate the formulation of a new periodic table of chemical compounds based on the ubiquity of nontrivial electronic band topology in solid-state materials.

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Low‐Frequency Current Fluctuations in Quasi‐1D (TaSe₄)₂I Weyl Semimetal Nanoribbons

Ghosh

Kargar

et al. 2022

Adv Elect Materials

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quasi-1D material is defined as a Weyl semimetal with Weyl points located above and below the Fermi level, forming pairs with the opposite chiral charge. At temperatures below the Peierls transition temperature T P = 248-263 K, (TaSe 4 ) 2 I reveals the charge-density-wave (CDW) phase. [4,[8][9][10][11][12][13] The quantum CDW phase consists of a periodic modulation of the electronic charge density accompanied by a periodic distortion of the atomic lattice. [14][15][16][17][18][19] It has been suggested that (TaSe 4 ) 2 I reveals a correlated topological phase, which arises from the formation of CDW in a Weyl semimetal. [11,12] This quasi-1D quantum material represents an interesting avenue for exploring the interplay of correlations and topology, as well as being an exciting system for examining new functionalities and electronic applications. [17,20] There are interesting applied physics and electronic materials aspects in the research of topological semimetals. The resistance and current density bottlenecks in downscaled metal interconnect motivate the search for new materials for the back end of the line (BEOL) interconnect applications. [21,22] When the interconnect linewidth scales below the electron mean free path, its resistivity increases in a power-law function due to Low-frequency current fluctuations, i.e., electronic noise, in quasi-1D (TaSe 4 ) 2 I Weyl semimetal nanoribbons are discussed. It is found that the noise spectral density is of the 1/f type and scales with the square of the current, S I ~ I 2 (f is the frequency). The noise spectral density increases by almost an order of magnitude and develops Lorentzian features near the temperature T ≈ 225 K. These spectral changes are attributed to the charge-density-wave phase transition even though the temperature of the noise maximum deviates from the reported Peierls transition temperature in bulk (TaSe 4 ) 2 I crystals. The noise level, normalized by the channel area, in these Weyl semimetal nanoribbons is surprisingly low, ≈10 −9 µm 2 Hz −1 at f = 10 Hz, when measured below and above the Peierls transition temperature. The obtained results shed light on the specifics of electron transport in quasi-1D topological Weyl semimetals and can be important for their proposed applications as downscaled interconnects.

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Surface charge induced Dirac band splitting in a charge density wave material (TaSe4)2I

Cited by 18 publications

References 44 publications

Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

All Topological Bands of All Stoichiometric Materials

Low‐Frequency Current Fluctuations in Quasi‐1D (TaSe₄)₂I Weyl Semimetal Nanoribbons

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Surface charge induced Dirac band splitting in a charge density wave material (TaSe4)2I

Cited by 18 publications

References 44 publications

Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

Absence of in-gap modes in charge density wave edge dislocations of the Weyl semimetal (TaSe$_4$)$_2$I

All Topological Bands of All Stoichiometric Materials

Low‐Frequency Current Fluctuations in Quasi‐1D (TaSe4)2I Weyl Semimetal Nanoribbons

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Product

Resources

About

Low‐Frequency Current Fluctuations in Quasi‐1D (TaSe₄)₂I Weyl Semimetal Nanoribbons