The determination of the commensurately modulated structure of tantalum tetratelluride

Bronsema, Klaas Derk; Smaalen, Sander van; Boer, J. L. de; Wiegers, G.A.; Jellinek, F.; Mahy, J.

doi:10.1107/s0108768187097805

Cited by 40 publications

(20 citation statements)

References 17 publications

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“…With CDW distortion, Ta atoms form Ta 3 clusters in the chain while Te atoms are slightly rotated around the Ta chains, which develop the equivalent 1D chains into three distinct types. The simulated CDW phase crystal structure is consistent with previous [38,39] and our experimental observations. The space group under the CDW phase is P4/ncc where C 4 rotation and inversion symmetry are preserved.…”

Section: Resultssupporting

confidence: 90%

Eightfold fermionic excitation in a charge density wave compound

Zhang

Sun

et al. 2020

Phys. Rev. B

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Unconventional quasiparticle excitations in condensed matter systems have become one of the most important research frontiers. Beyond twofold and fourfold degenerate Weyl and Dirac fermions, threefold, sixfold, and eightfold symmetry protected degeneracies have been predicted. However they remain challenging to realize in solid state materials. Here the charge density wave compound TaTe 4 is proposed to hold eightfold fermionic excitation and Dirac point in energy bands. High quality TaTe 4 single crystals are prepared, where the charge density wave is revealed by directly imaging the atomic structure and a pseudogap of about 45 meV on the surface. Shubnikov-de Haas oscillations of TaTe 4 are consistent with band structure calculation. Scanning tunneling microscopy/spectroscopy reveals atomic step edge states on the surface of TaTe 4 . This work uncovers that the charge density wave is able to induce new topological phases and sheds new light on the novel excitations in condensed matter materials.

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Section: Resultssupporting

confidence: 90%

Eightfold fermionic excitation in a charge density wave compound

Zhang

Sun

et al. 2020

Phys. Rev. B

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“…This is in agreement with the work of Eaglesham, Bird, Withers & Steeds (1985) who concluded from convergent-beam electron diffraction experiments that the RT TaTe4 space group was P4/mcc, but differs from the work of Bronsema, van Smaalen, de Boer, Wiegers, Jellinek & Mahy (1987) and from that of Sahu & Walker (1985) who, on the basis of X-ray experiments and Landau-theory calculations, respectively, suggested P4/ncc.…”

Section: Discussionsupporting

confidence: 78%

A dualistic interpretation of the incommensurate modulated structures of NbTe₄

Prodan¹,

Boswell²

1987

Acta Crystallogr Sect B

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The incommensurate/discommensurate modulated structures of NbTe4 are described using the dualistic approach, an alternative to the superspace group formalism of de Wolff [Acta Cryst. (1984), A40, 34-42]. On the basis of electron diffraction experiments, the room-temperature modulated structure is P 4/ mcc described dualistically as 14/mmm which is equivalent to the previously reported superspace group notation wP4/mcc -i-~ determined from X-ray diffraction. On cooling NbTe4, changes occur in the electron diffraction patterns over the temperature range I00 to 50 K, before the lock-in transition to the commensurate (2ax3c) superstructure. Although this low temperature modulation can formally be described with the same dualistic and superspace group symbols as the room-temperature one, but with the basic and modulation unit cells enlarged from a and x/2a to v~a and 2a respectively, it in fact represents a discommensuration phase, where the low-temperature (2ax3c) superstructure is nucleated within the incommensurate surrounding and accommodated to it with periodic discommensurations.

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“…In contrast, NbTe 4 and TaTe 4 are metallic, their high temperature crystal structure contains uniform chains, and exhibit structural modulations toward a 2a × 2a × 3c commensurate phase. TaTe 4 has a transition to this commensurate phase at around 450 K [12] while its isostructural counterpart, NbTe 4 , crosses several incommensurate phases before locking into the final commensurate one at 50 K [13,14]. Because of the presence of chains of transition metal atoms and the high-temperature metallic character, these CDWs have been attributed to a Peierls-type mechanism as in other quasi-1D metals [15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Competition between Ta-Ta and Te-Te bonding leading to the commensurate charge density wave in TaTe4

et al. 2022

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The origin of the charge density wave in TaTe 4 is discussed on the basis of a first-principles density functional theory analysis of the Fermi surface, electron-hole response function, phonon band structure of the average structure, and structural optimization of the modulated phase. Analysis of the band structure and Fermi surface of the average structure clearly proves that despite the presence of TaTe 4 chains in the crystal structure, TaTe 4 is in fact a 3D material as far as the electronic structure near the Fermi level is concerned. A Fermi surface nesting mechanism is dismissed as the origin of the 2a × 2a × 3c structural modulation. The optimized 2a × 2a × 3c structure, which is found to be the more stable modulation in agreement with the experimental observations, can be obtained directly from a soft-phonon mode computed for the undistorted structure. Our results suggest that the driving force for the distortion is the maximization of Ta-Ta metal-metal bonding subject to inducing the minimum bonding decrease in the Te sublattice.

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The determination of the commensurately modulated structure of tantalum tetratelluride

Cited by 40 publications

References 17 publications

Eightfold fermionic excitation in a charge density wave compound

Eightfold fermionic excitation in a charge density wave compound

A dualistic interpretation of the incommensurate modulated structures of NbTe₄

Competition between Ta-Ta and Te-Te bonding leading to the commensurate charge density wave in TaTe4

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The determination of the commensurately modulated structure of tantalum tetratelluride

Cited by 40 publications

References 17 publications

Eightfold fermionic excitation in a charge density wave compound

Eightfold fermionic excitation in a charge density wave compound

A dualistic interpretation of the incommensurate modulated structures of NbTe4

Competition between Ta-Ta and Te-Te bonding leading to the commensurate charge density wave in TaTe4

Contact Info

Product

Resources

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A dualistic interpretation of the incommensurate modulated structures of NbTe₄