Topological nodal-line semimetal in nonsymmorphic 
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-phase 
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Huang, Huaqing; Jin, Kyung-Hwan; Liu, Feng

doi:10.1103/physrevb.96.115106

Cited by 30 publications

(23 citation statements)

References 66 publications

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“…For example, β-Ag 2 Te was identified as a topological insulator with gapless Dirac-type surface states [18]. The orthorhombic Cmce − Ag 2 S was predicted to be a topological nodal-line semimetal with a single glide symmetry-protected nodal loop [19]. Unfortunately, this phase is yet to be synthesized and the stable α-Ag 2 S is just a conventional semiconductor at ambient pressure.…”

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confidence: 99%

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

et al. 2020

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We report two reversible pressure-induced isosymmetric phase transitions in α-Ag 2 S that are accompanied by two compressive anomalies at 7.5 and 16 GPa, respectively. The first transition arises from a sudden and drastic puckering of the wrinkled Ag-S layers, which leads to an anomalous structural softening at high pressure and gives rise to the ultrahigh compressive ductility in α-Ag 2 S. The second transition stems from a pressure-driven electronic state crossover from a conventional semiconductor to a topological metal. The band-crossing points near the Fermi energy form a nodal-line structure due to the preservation of the time-reversal and space-inversion symmetries under pressure. Our findings not only reveal the underlying mechanism responsible for the ultrahigh ductility in this class of inorganic semiconductors, but also provide a distinctive member to the growing family of topological metals and semimetals.

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confidence: 99%

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

et al. 2020

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“…With strong spin-orbit coupling (SOC), the nodal lines in these materials are either protected by reflection or mirror symmetry, or gapped out due to the lack of such symmetries [18][19][20][21][22]. Recent examples/promising candidates of NLSM include Pb(Tl)TaSe 2 [23,24], ZrSiX (X = S, Se, Te) [25,26], CaP 3 [27], Ca 3 P 2 [28], BaSn 2 [29], Ag 2 S [30], CaTe [31], Cu 3 PdN [32], GdSbTe [33], body-centered orthorhombic C 16 [34], compressed black phosphorus [35], etc. However, the band structures of these materials are often so complex that multiple irrelevant trivial or nontrivial pockets coexist with the drumlike surface states at the Fermi level, masking the quantum transport signals from the nodal lines.…”

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Topological surface electronic states in candidate nodal-line semimetal CaAgAs

Wang

Emmanouilidou

et al. 2017

Phys. Rev. B

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We investigate systematically the bulk and surface electronic structure of the candidate nodal-line semimetal CaAgAs by angle-resolved photoemission spectroscopy and density functional calculations. We observed a metallic, linear, non-k z -dispersive surface band that coincides with the high-binding-energy part of the theoretical topological surface state, proving the topological nontriviality of the system. An overall downshift of the experimental Fermi level points to a rigid-band-like p doping of the samples, due possibly to Ag vacancies in the as-grown crystals. DOI: 10.1103/PhysRevB.96.161112 The discovery of topologically nontrivial systems has dominated the field of condensed matter physics over the past decade. Unique nontrivial topological properties in these fermionic systems relate concepts from high-energy physics to various quasiparticle excitations in condensed matter, causing the systems to resist small perturbations due to the protection by particular topological invariants [1,2]. In the so-called topological semimetals, such nontrivialities appear as the touching of valence and conduction bands at isolated points, closed lines, or planes in momentum space. Such materials exhibit chiral anomaly [3,4], topological surface Fermi arcs [5][6][7][8][9][10][11][12][13], and/or superconducting zero modes [14][15][16], whose quasiparticle excitations correspond directly to the Dirac, Weyl, and Majorana fermions. These quasiparticles differ from the actual entities in high-energy physics, but obey the same underlying principles in quantum field theory, offering the opportunity to investigate the fundamental physical laws that govern a large subset of quantum condensed matter as well as creating a new approach for developing a broad range of low-power, high-efficiency spintronic and quantum computing devices [1,2,17].Topological nodal-line semimetals (NLSMs) exhibit novel topological properties that are manifested by surface states in the form of a drumlike membrane living in the continuous toroidal isosurface gap in three-dimensional (3D) momentum space. With strong spin-orbit coupling (SOC), the nodal lines in these materials are either protected by reflection or mirror symmetry, or gapped out due to the lack of such symmetries [18][19][20][21][22] realizing a clean, "hydrogen-atom-like" NLSM is therefore of urgent need. Single-crystalline CaAgAs is theoretically predicted to be among the best candidate NLSMs since its theoretical Fermi surface contains no more than a circular nodal contour linked by the topological surface state [36], which gives rise to the ultralow magnetoresistance found by transport measurements [37]. In this Rapid Communication, we systematically investigate the NLSM state of CaAgAs which is solely protected by mirror reflection symmetry through a comparison between angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations. Our DFT calculations show that without SOC, a topological nodal ring enclosing appears in the first Bri...

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“…Therefore, the spin-orbit coupling can give origin to topological band inversions due to the lack of non-symmorphic symmetries [57][58][59][60][61][62], opening the way for further theoretical and experimental investigations in YRe2SiC beyond conventional superconductivity.…”

Section: Electronic Structure Calculationmentioning

confidence: 99%

Possible multiband superconductivity in the quaternary carbide YRe₂SiC

Faria

Ferreira

Corrêa

et al. 2021

Supercond. Sci. Technol.

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We report for the first time the occurrence of superconductivity in the quaternary silicide carbide YRe2SiC with Tc ≈ 5.9 K. The emergence of superconductivity was confirmed by means of magnetic susceptibility, electrical resistivity, and heat capacity measurements. The presence of a well developed heat capacity feature at Tc confirms that superconductivity is a bulk phenomenon, while a second feature in the heat capacity near 0.5 Tc combined with the unusual temperature dependence of the upper critical field Hc2(T) indicate the presence of a multiband superconducting state. Additionally, the linear dependence of the lower critical field Hc1 with temperature resemble the behavior found in compounds with unconventional pairing symmetry. Band structure calculations reveal YRe2SiC could harbor a non-trivial topological state and that the low-energy states occupy multiple disconnected sheets at the Fermi surface, with different degrees of hybridization, nesting, and screening effects, therefore making unconventional multiband superconductivity plausible.

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Topological nodal-line semimetal in nonsymmorphic Cmce -phase Ag2S

Cited by 30 publications

References 66 publications

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

Topological surface electronic states in candidate nodal-line semimetal CaAgAs

Possible multiband superconductivity in the quaternary carbide YRe₂SiC

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Topological nodal-line semimetal in nonsymmorphic Cmce -phase Ag2S

Cited by 30 publications

References 66 publications

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

Isosymmetric phase transitions, ultrahigh ductility, and topological nodal lines in α−Ag2S

Topological surface electronic states in candidate nodal-line semimetal CaAgAs

Possible multiband superconductivity in the quaternary carbide YRe2SiC

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Possible multiband superconductivity in the quaternary carbide YRe₂SiC