Symmetry-enforced band crossings in trigonal materials: Accordion states and Weyl nodal lines

Chan, Yang-Hao; Kilic, Berkay; Hirschmann, Moritz M.; Chiu, Ching-Kai; Schoop, Leslie M.; Joshi, Darshan G.; Schnyder, Andreas P.

doi:10.1103/physrevmaterials.3.124204

Cited by 31 publications

(29 citation statements)

References 82 publications

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“…However, for many materials, the spatial symmetry of the crystal structure implies that band touching can happen in the form of extended nodal structures, such as nodal lines or nodal surfaces [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Furthermore, nodal lines and nodal surfaces can also arise in parameterdependent quantum systems [22][23][24] in the presence of fine-tuning or symmetries.…”

mentioning

confidence: 99%

Weyl-point teleportation

György¹,

Varjas²,

Pintér³

et al. 2021

Preprint

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In this work, we describe the phenomenon of Weyl-point teleportation. Weyl points usually move continuously in the configuration parameter space of a quantum system when the control parameters are varied continuously. However, there are special transition points in the control space where the continuous motion of the Weyl points is disrupted. In such transition points, an extended nodal structure (nodal line or nodal surface) emerges, serving as a wormhole for the Weyl points, allowing their teleportation in the configuration space. A characteristic side effect of the teleportation is that the motional susceptibility of the Weyl point diverges in the vicinity of the transition point, and this divergence is characterized by a universal scaling law. We exemplify these effects via a two-spin model and a Weyl Josephson circuit model. We expect that these effects generalize to many other settings including electronic band structures of topological semimetals.

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confidence: 99%

Weyl-point teleportation

György¹,

Varjas²,

Pintér³

et al. 2021

Preprint

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“…The presented characterization of TPs applies to spinless representations in all space groups (magnetic or not, nonsymmorphic or not), and as such provides that next essential piece of information towards the growing catalogue of symmetry-protected and symmetry-enforced band nodes [52,[86][87][88]. In this regard, we conclude with one speculation that may constitute an interesting research avenue for the near future.…”

Section: Discussionmentioning

confidence: 70%

Triple nodal points characterized by their nodal-line structure in all magnetic space groups

Lenggenhager¹,

Liu²,

Neupert³

et al. 2022

Preprint

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We analyze triply degenerate nodal points [or triple points (TPs) for short] in energy bands of crystalline solids. Specifically, we focus on spinless band structures, i.e., when spin-orbit coupling is negligible, and consider TPs formed along high-symmetry lines in the momentum space by a crossing of three bands transforming according to a 1D and a 2D irreducible corepresentation (ICR) of the little co-group. The result is a complete classification of such TPs in all magnetic space groups, including the non-symmorphic ones, according to several characteristics of the nodal-line structure at and near the TP. We show that the classification of the presently studied TPs is exhausted by 13 magnetic point groups (MPGs) that can arise as the little co-group of a high-symmetry line and which support both 1D and 2D spinless ICRs. For 10 of the identified MPGs, the TP characteristics are uniquely determined without further information; in contrast, for the 3 MPGs containing sixfold rotation symmetry, two types of TPs are possible, depending on the choice of the crossing ICRs. The classification result for each of the 13 MPGs is illustrated with first-principles calculations of a concrete material candidate.

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“…140) Zr 2 Ir using magnetic susceptibility, electrical resistivity, heat capacity, and muon-spin rotation/relaxation (μSR) techniques. Recent work has revealed that the nonsymmorphic symmetry can host novel topological phases [21] and topological superconductivity, thus making Zr 2 Ir an ideal candidate material. Initial band-structure calculations have revealed that Zr 2 Ir is a topological semimetal with a symmetry-enforced Fermi-level degeneracy at high-symmetry points [22,23].…”

Section: Introductionmentioning

confidence: 99%

Superconducting ground state of the nonsymmorphic superconducting compound Zr2Ir

et al. 2021

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The nonsymmorphic Zr 2 Ir alloy is a possible topological semimetal candidate material and as such may be part of an exotic class of superconductors. Zr 2 Ir is a superconductor with a transition temperature of 7.4 K with critical fields of 19.6(3) mT and 3.79(3) T, as determined by heat capacity and magnetization. Zero-field muon spin relaxation measurements show that time-reversal symmetry is preserved in these materials. The specific heat and transverse field muon spin rotation measurements rule out any possibility to have a nodal or anisotropic superconducting gap, revealing a conventional s-wave nature in the superconducting ground state. Therefore this system is found to be a conventional nonsymmorphic superconductor, with time-reversal symmetry being preserved and an isotropic superconducting gap.

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Symmetry-enforced band crossings in trigonal materials: Accordion states and Weyl nodal lines

Cited by 31 publications

References 82 publications

Weyl-point teleportation

Weyl-point teleportation

Triple nodal points characterized by their nodal-line structure in all magnetic space groups

Superconducting ground state of the nonsymmorphic superconducting compound Zr2Ir

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