Signatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb<sub>2</sub>

Kumar, Nitesh; Yao, Mengyu; Nayak, J.; Vergniory, Maia G.; Bannies, J.; Wang, Zhijun; Schröter, Niels B. M.; Strocov, Vladimir N.; Müchler, Lukas; Shi, Wujun; Rienks, E. D. L.; Mañes, Juan L.; Shekhar, Chandra; Parkin, Stuart S. P.; Fink, J.; Fecher, Gerhard H.; Sun, Yan; Bernevig, B. Andrei; Felser, Claudia

doi:10.1002/adma.201906046

Cited by 44 publications

(19 citation statements)

References 42 publications

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“…[60] The sixfold degeneracies at the R points are stem from the three-fold rotation symmetry. [61,62] In consistent with the nodal lines and the multifold degeneracies, the Fermi surface consists of a large cubelike pocket in the center of the Brillouin zone, and a network of small electron and hole pockets connected along the edges of the Brillouin zone [Fig. 9(b)].…”

Section: The Metallization Of Orthorhombic Phase Under Compression An...mentioning

confidence: 88%

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

et al. 2020

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Based on first-principles simulations and calculations, we explore the evolutions of crystal structure, electronic structure and transport properties of quasi 2D layered PdS2 under compression by uniaxial stress and hydrostatic pressure. An interesting ferroelastic phase transition with lattice reorientation is revealed under uniaxial compressive stress, which originates from the bond reconstructions of the unusual PdS4 square-planar coordination. By contrast, the layered structure transforms to a 3D cubic pyrite-type structure under hydrostatic pressure. In contrary to the experimental proposed coexistence of layered PdS2-type structure with cubic pyrite-type structure at intermediate pressure range, we predict that the compression-induced intermediate phase showing the same structure symmetry with the ambient phase, except of sharply shrinking interlayer-distances. The coordination of the Pd ions not only plays crucial roles in the structural transition, but also lead to electronic structure and transport properties variations, which changes from square-planar to distorted octahedron in the intermediate phase, resulting in bandwidth broaden and orbital-selective metallization. In addition, the superconductivity in the cubic pyrite-type structure comes from the strong electron-phonon coupling in presence of topological nodal-line states. The strong interplay between structural transition, metallization and superconductivity in PdS2 provide a good platform to study the fundamental physics of the interactions between crystal structure and transport behavior, and the competition or cooperation between diverse phases.

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Section: The Metallization Of Orthorhombic Phase Under Compression An...mentioning

confidence: 88%

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

et al. 2020

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“…Kumar et al provided signatures of this degeneracy with the help of ARPES. [361][362][363] The sister compound PtBi2 also contains the sextuple point, but in the unoccupied conduction band. The extremely large MR in this compound has been attributed to the presence of independent Dirac points in the occupied valence band.…”

Section: New Fermionsmentioning

confidence: 99%

Topological Quantum Materials from the Viewpoint of Chemistry

et al. 2020

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Topology, a mathematical concept, has recently become a popular and truly transdisciplinary topic encompassing condensed matter physics, solid state chemistry, and materials science. Since there is a direct connection between real space, namely atoms, valence electrons, bonds and orbitals, and reciprocal space, namely bands and Fermi surfaces, via symmetry and topology, classifying topological materials within a single-particle picture is possible. Currently, most materials are classified as trivial insulators, semimetals and metals, or as topological insulators, Dirac and Weyl nodal-line semimetals, and topological metals. The key ingredients for topology are: certain symmetries, the inert pair effect of the outer electrons leading to inversion of the conduction and valence bands, and spin-orbit coupling. This review presents the topological concepts related to solids from the viewpoint of a solid-state chemist, summarizes techniques for growing single crystals, and describes basic physical property measurement techniques to characterize topological materials beyond their structure and provide examples of such materials. Finally, a brief outlook on the impact of topology in other areas of chemistry is provided at the end of the article.

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“…Indeed, despite the relatively large number of confirmed Weyl and Dirac systems , few show band crossings in close proximity to the Fermi level. For semimetals hosting unconventional fermions the list is smaller still, especially given that to date, few such materials have actually been synthesized and checked experimentally for the presence of nodal fermions [42][43][44][45][46][47][48][49][50].…”

Section: Introductionmentioning

confidence: 99%

Sixfold fermion near the Fermi level in cubic PtBi2

et al. 2021

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We show that the cubic compound PbBi2 is a topological semimetal hosting a sixfold band touching point in close proximity to the Fermi level. Using angle-resolved photoemission spectroscopy, we map the band structure of the system, which is in good agreement with results from density functional theory. Further, by employing a low energy effective Hamiltonian valid close to the crossing point, we study the effect of a magnetic field on the sixfold fermion. The latter splits into a total of twenty Weyl cones for a Zeeman field oriented in the diagonal, (111) direction. Our results mark cubic PbBi2 as an ideal candidate to study the transport properties of gapless topological systems beyond Dirac and Weyl semimetals.

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Signatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb₂

Cited by 44 publications

References 42 publications

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

Topological Quantum Materials from the Viewpoint of Chemistry

Sixfold fermion near the Fermi level in cubic PtBi2

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Signatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb2

Cited by 44 publications

References 42 publications

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

Structural transition, metallization, and superconductivity in quasi-two-dimensional layered PdS2 under compression

Topological Quantum Materials from the Viewpoint of Chemistry

Sixfold fermion near the Fermi level in cubic PtBi2

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Signatures of Sixfold Degenerate Exotic Fermions in a Superconducting Metal PdSb₂