Observation of topological edge states in the quantum spin Hall insulator 
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Wang, Xuguang; Geng, Daiyu; Yan, Dayu; Hu, Wenqi; Zhang, Hexu; Yue, Shaosheng; Sun, Zhenyu; Kumar, Shiv; Schwier, Eike F.; Shimada, Kenya; Cheng, Peng; Chen, Lan; Nie, Simin; Wang, Zhijun; Shi, Youguo; Zhang, Yi‐Qi; Wu, Kehui; Feng, Baojie

doi:10.1103/physrevb.104.l241408

Cited by 14 publications

(10 citation statements)

References 33 publications

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“…Theoretical studies have proposed that the monolayer Ta 2 M 3 Te 5 (M = Pd, Ni) behaves as 2D quadrupole TIs characterized by double band-inversion interactions. , Angle-resolved photoemission spectroscopy and scanning tunneling microscopy experimentally confirm that the monolayer Ta 2 Pd 3 Te 5 behaves as quantum spin Hall insulator, with a 43 meV inverted band gap at the Fermi level . Furthermore, the recent work on bulk Ta 2 Pd 3 Te 5 demonstrates the coexistence of bulk insulating gap, in-gap edge conducting state, and edge gap as signatures of 2D second-order TI candidate, with observed tunable Luttinger liquid behavior in edge channels across different scales .…”

Section: Introductionmentioning

confidence: 91%

“…23,24 Angle-resolved photoemission spectroscopy and scanning tunneling microscopy experimentally confirm that the monolayer Ta 2 Pd 3 Te 5 behaves as quantum spin Hall insulator, with a 43 meV inverted band gap at the Fermi level. 25 Furthermore, the recent work on bulk Ta 2 Pd 3 Te 5 demonstrates the coexistence of bulk insulating gap, in-gap edge conducting state, and edge gap as signatures of 2D secondorder TI candidate, with observed tunable Luttinger liquid behavior in edge channels across different scales. 26 Pressure effect has triggered superconductivity in correlated TI materials, such as α-Bi 4 Br 4 , Bi 2 Te 3 , and ZrTe 5 , 27−30 offering an alternative avenue for topological superconductivity.…”

Section: Introductionmentioning

confidence: 99%

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Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

Yu,

Yan,

Guo

et al. 2024

J. Am. Chem. Soc.

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Topological insulators offer significant potential to revolutionize diverse fields driven by nontrivial manifestations of their topological electronic band structures. However, the realization of superior integration between exotic topological states and superconductivity for practical applications remains a challenge, necessitating a profound understanding of intricate mechanisms. Here, we report experimental observations for a novel superconducting phase in the pressurized second-order topological insulator candidate Ta 2 Pd 3 Te 5 , and the high-pressure phase maintains its original ambient pressure lattice symmetry up to 45 GPa. Our in situ high-pressure synchrotron X-ray diffraction, electrical transport, infrared reflectance, and Raman spectroscopy measurements, in combination with rigorous theoretical calculations, provide compelling evidence for the association between the superconducting behavior and the densified phase. The electronic state change around 20 GPa was found to modify the topology of the Fermi surface directly, which synergistically fosters the emergence of robust superconductivity. In-depth comprehension of the fascinating properties exhibited by the compressed Ta 2 Pd 3 Te 5 phase is achieved, highlighting the extraordinary potential of topological insulators for exploring and investigating high-performance electronic advanced devices under extreme conditions.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

Yu,

Yan,

Guo

et al. 2024

J. Am. Chem. Soc.

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“…SOC often plays important roles to engineering topological states, such as quantum spin Hall effect in graphene 32,33 and Ta 2 M 3 Te 5 (M=Pd,Ni) compounds 34,35 , 3D large-SOC-gap topological insulator in Bi 2 Se 3 and NaCaBi families 36,37 , and so on. In terms of the the patterned PtTe 2 monolayer, once including SOC, the Te-p z dominated band around Γ splits due to the Rashba SOC induced by the Te vacancy, as shown in Fig.…”

Section: A Electronic Band Structuresmentioning

confidence: 99%

Large spin Hall conductivity and excellent hydrogen evolution reaction activity in unconventional PtTe1.75 monolayer

Shao¹,

Deng²,

Sheng³

et al. 2022

Preprint

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Two-dimensional (2D) materials have gained lots of attention due to the potential applications. In this work, we propose that based on first-principles calculations, the (2×2) patterned PtTe2 monolayer with kagome lattice formed by the well-ordered Te vacancy (PtTe1.75) hosts large spin Hall conductivity (SHC) and excellent hydrogen evolution reaction (HER) activity. The unconventional nature relies on the A1@1b band representation (BR) of the highest valence band without SOC. The large SHC comes from the Rashba spin-orbit coupling (SOC) in the noncentrosymmetric structure induced by the Te vacancy. Even though it has a metallic SOC band structure, the Z2 invariant is well defined due to the existence of the direct band gap and is computed to be nontrivial. The calculated SHC is as large as 1.25×10 3 e (Ω cm) −1 at the Fermi level (EF ). By tuning the chemical potential from EF − 0.3 to EF + 0.3 eV, it varies rapidly and monotonically from −1.2 × 10 3 to 3.1×10 3 e (Ω cm) −1 . In addition, we also find the Te vacancy in the patterned monolayer can induce excellent HER activity. Our results not only offer a new idea to search 2D materials with large SHC, i.e., by introducing inversion-symmetry breaking vacancies in large SOC systems, but also provide a feasible system with tunable SHC (by applying gate voltage) and excellent HER activity.

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“…Ta 2 Ni 3 Te 5 is part of a class of layered 2DTIs, Ta 2 M 3 X 5 (M = Ni, Pd; X = Se, Te), that has recently gained interest as a platform to explore topological states. Some of the materials in this class have been shown to have exotic properties such as superconductivity, excitonic states, edge states, and Luttinger liquid behavior. − In particular, Ta 2 Ni 3 Te 5 is also predicted to possess a second-order topology with gapless corner states, making it a quadrupole topological insulator. The double band inversion in Ta 2 Ni 3 Te 5 is expected to manifest as a band gap of 65 meV, large enough to be observed at room temperature.…”

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confidence: 99%

In-Plane Anisotropy in the Layered Topological Insulator Ta₂Ni₃Te₅ Investigated via TEM and Polarized Raman Spectroscopy

Harrison,

Jeff,

DeStefano

et al. 2024

ACS Nano

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Ni) has emerged as a platform to study 2D topological insulators, which have exotic properties such as spin-momentum locking and the presence of Dirac fermions for use in conventional and quantum-based electronics. In particular, Ta 2 Ni 3 Te 5 has been shown to have superconductivity under pressure and is predicted to have second-order topology. Despite being an interesting material with fascinating physics, the detailed crystalline and phononic properties of this material are still unknown. In this study, we use transmission electron microscopy (TEM) and polarized Raman spectroscopy (PRS) to reveal the anisotropic properties of exfoliated few-layer Ta 2 Ni 3 Te 5 . An electron diffraction and TEM study reveals structural anisotropy in the material, with a preferential crystal orientation along the [010] direction. Through Raman spectroscopy, we discovered 15 vibrational modes, 3 of which are ultralow-frequency modes, which show anisotropic response with sample orientation varying with the polarization of the incident beam. Using angle-resolved PRS, we assigned the vibrational symmetries of 11 modes to A g and two modes to B 3g . We also found that linear dichroism plays a role in understanding the Raman signature of this material, which requires the use of complex elements in the Raman tensors. The anisotropy of the Raman scattering also depends on the excitation energies. Our observations reveal the anisotropic nature of Ta 2 Ni 3 Te 5 , establish a quick and nondestructive Raman fingerprint for determining sample orientation, and represent a significant advance in the fundamental understanding of the two-dimensional topological insulator (2DTI) Ta 2 Ni 3 Te 5 material.

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Observation of topological edge states in the quantum spin Hall insulator Ta2Pd3Te5

Cited by 14 publications

References 33 publications

Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

Large spin Hall conductivity and excellent hydrogen evolution reaction activity in unconventional PtTe1.75 monolayer

In-Plane Anisotropy in the Layered Topological Insulator Ta₂Ni₃Te₅ Investigated via TEM and Polarized Raman Spectroscopy

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Observation of topological edge states in the quantum spin Hall insulator Ta2Pd3Te5

Cited by 14 publications

References 33 publications

Observation of Emergent Superconductivity in the Topological Insulator Ta2Pd3Te5 via Pressure Manipulation

Observation of Emergent Superconductivity in the Topological Insulator Ta2Pd3Te5 via Pressure Manipulation

Large spin Hall conductivity and excellent hydrogen evolution reaction activity in unconventional PtTe1.75 monolayer

In-Plane Anisotropy in the Layered Topological Insulator Ta2Ni3Te5 Investigated via TEM and Polarized Raman Spectroscopy

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Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

Observation of Emergent Superconductivity in the Topological Insulator Ta₂Pd₃Te₅ via Pressure Manipulation

In-Plane Anisotropy in the Layered Topological Insulator Ta₂Ni₃Te₅ Investigated via TEM and Polarized Raman Spectroscopy