Observation of topological states residing at step edges of WTe2

Peng, Lang; Yuan, Yuan; Li, Gang; Yang, Xing; Ji, Wei; Yi, Changjiang; Shi, Youguo; Fu, Ying-Shuang

doi:10.1038/s41467-017-00745-8

Cited by 159 publications

(154 citation statements)

References 45 publications

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“…Recently, VIB‐group layered transition metal dichalcogenides (TMDs), MX 2 (M = Mo, W; X = S, Se, Te), attracted extensive attention due to rich physiochemical properties, ranging from catalysis, topological states, valley polarization, even to superconductivity . These multiple electronic properties essentially originate from varied crystal structures of TMD materials.…”

Section: The Parity Products Of Valence Bands Defined By the Curving mentioning

confidence: 99%

Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States

et al. 2019

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Recently, VIB-group layered transition metal dichalcogenides (TMDs), MX 2 (M = Mo, W; X = S, Se, Te), attracted extensive attention due to rich physiochemical properties, ranging from catalysis, [1][2][3] topological states, [4][5][6][7][8][9][10][11][12][13][14][15][16] valley polarization, [17][18][19][20][21][22] even to superconductivity. [23][24][25][26][27][28] These multiple electronic properties essentially originate from varied crystal structures of TMD materials. The typical crystal structure in TMD materials is the 2H-type structure with [X-M-X] atoms in ABA stacking in each monolayer (Figure S1a, Supporting Information). Usually, 2H MX 2 materials are semiconducting, such as, 2H MoS 2 , where the valley polarization was widely studied. [17][18][19] Also, Ising superconductivity was observed when the TMD materials are reduced down to a few or even oneRecently the metastable 1T′-type VIB-group transition metal dichalcogenides (TMDs) have attracted extensive attention due to their rich and intriguing physical properties, including superconductivity, valleytronics physics, and topological physics. Here, a new layered WS 2 dubbed "2M" WS 2 , is constructed from 1T′ WS 2 monolayers, is synthesized. Its phase is defined as 2M based on the number of layers in each unit cell and the subordinate crystallographic system. Intrinsic superconductivity is observed in 2M WS 2 with a transition temperature T c of 8.8 K, which is the highest among TMDs not subject to any fine-tuning process. Furthermore, the electronic structure of 2M WS 2 is found by Shubnikov-de Haas oscillations and first-principles calculations to have a strong anisotropy. In addition, topological surface states with a single Dirac cone, protected by topological invariant Z 2 , are predicted through first-principles calculations. These findings reveal that the new 2M WS 2 might be an interesting topological superconductor candidate from the VIB-group transition metal dichalcogenides.

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Section: The Parity Products Of Valence Bands Defined By the Curving mentioning

confidence: 99%

Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States

et al. 2019

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“…Recently, layered transition-metal dichalcogenides (TMDs), materials with chemical formula i M Q 2 , with M being a transitionmetal and Q a chalcogen (S, Se and Te), have attracted wide technological interest due to their capacity of being isolated into one layer, like graphene does 5,6 , and the wide spectrum of the electronic properties they present, being metals, semimetals, semiconductors and insulators 7 . Recently, there were reported TMDs presenting exotic electronic properties, such as having topological insulator states 8 , being a Weyl semimetal 9 and displaying charge density waves 7 . The wide spectrum of properties presented by TMDs is enabled by their large number of chemical compositions combining M and Q and the existence of several polymorphic phases 5,7,10 .…”

Section: Introductionmentioning

confidence: 99%

Ab initio investigation of structural stability and exfoliation energies in transition metal dichalcogenides based on Ti-, V-, and Mo-group elements

Bastos

Besse

Silva

et al. 2019

Phys. Rev. Materials

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In this work, we report an ab initio investigation based on density functional theory of the structural, energetic and electronic properties of 2D layered chalcogenides compounds based in the combination of the transition-metals (Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and chalcogenides (S, Se, Te) in three polymorphic phases: trigonal prismatic (2H), octahedral (1T) and distorted octahedral (1T d ). We determined the most stable phases for each compound, verifying the existence of the 1T d phase for a small number of the compounds and we have also identified the magnetic compounds. In addition, with the determination of the exfoliation energies, we indicated the potential candidates to form one layer material and we have also found a relation between the exfoliation energy and the effective Bader charge in the metal, suggesting that when the materials present small exfoliation energy, it is due to the Coulomb repulsion between the chalcogen planes. Finally, we analyzed the electronic properties, identifying the semiconductor, semimetal and metal materials and predicting the band gap of the semiconductors. In our results, the dependence of the band gap on the d-orbital is explicit. In conclusion, we have investigated the properties of stable and metastable phases for a large set of TMD materials, and our findings may be auxiliary in the synthesis of metastable phases and in the development of new TMDs applications. arXiv:1903.08112v1 [cond-mat.mtrl-sci]

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“…The band inversion happens between transition-metal d orbitals and chalcogenide p orbitals, and the SOC interaction further opens a fundamental band gap 11 . Recently, great experimental progress have been made in the single-layer 1 T ’-WTe 2 22–26 . For example, the transport measurement on the exfoliated monolayer WTe 2 sheet showed the existence of topological edge conductance 22 .…”

Section: Introductionmentioning

confidence: 99%

Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T’-WTe2

et al. 2018

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The two-dimensional topological insulators host a full gap in the bulk band, induced by spin–orbit coupling (SOC) effect, together with the topologically protected gapless edge states. However, it is usually challenging to suppress the bulk conductance and thus to realize the quantum spin Hall (QSH) effect. In this study, we find a mechanism to effectively suppress the bulk conductance. By using the quasiparticle interference technique with scanning tunneling spectroscopy, we demonstrate that the QSH candidate single-layer 1T’-WTe2 has a semimetal bulk band structure with no full SOC-induced gap. Surprisingly, in this two-dimensional system, we find the electron–electron interactions open a Coulomb gap which is always pinned at the Fermi energy (EF). The opening of the Coulomb gap can efficiently diminish the bulk state at the EF and supports the observation of the quantized conduction of topological edge states.

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Observation of topological states residing at step edges of WTe2

Cited by 159 publications

References 45 publications

Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States

Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States

Ab initio investigation of structural stability and exfoliation energies in transition metal dichalcogenides based on Ti-, V-, and Mo-group elements

Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T’-WTe2

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Observation of topological states residing at step edges of WTe2

Cited by 159 publications

References 45 publications

Discovery of Superconductivity in 2M WS2 with Possible Topological Surface States

Discovery of Superconductivity in 2M WS2 with Possible Topological Surface States

Ab initio investigation of structural stability and exfoliation energies in transition metal dichalcogenides based on Ti-, V-, and Mo-group elements

Observation of Coulomb gap in the quantum spin Hall candidate single-layer 1T’-WTe2

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Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States

Discovery of Superconductivity in 2M WS₂ with Possible Topological Surface States