Robust topological nodal lines in halide carbides

2019 ◽  
Vol 21 (36) ◽  
pp. 20262-20268 ◽  
Author(s):  
Anh Pham ◽  
Frank Klose ◽  
Sean Li
Keyword(s):  
Nodal Line ◽  
Nodal Lines ◽  
Symmetry Protected ◽  
2D And 3D

This study predicts the existence of a symmetry protected nodal line state in Y2C2I2 in both 2D and 3D.

scholarly journals Glide symmetry protected higher-order topological insulators from semimetals with butterfly-like nodal lines

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Xiaoting Zhou ◽  
Chuang-Han Hsu ◽  
Cheng-Yi Huang ◽  
Mikel Iraola ◽  
Juan L. Mañes ◽  
...  
Keyword(s):  
Topological Insulator ◽  
Topological Insulators ◽  
Surface States ◽  
Nodal Line ◽  
Higher Order ◽  
Dirac Fermion ◽  
Space Groups ◽  
Nodal Lines ◽  
Topological Semimetals ◽  
Symmetry Protected

AbstractMost topological insulators (TIs) discovered today in spinful systems can be transformed from topological semimetals (TSMs) with vanishing bulk gap via introducing the spin-orbit coupling (SOC), which manifests the intrinsic links between the gapped topological insulator phases and the gapless TSMs. Recently, we have discovered a family of TSMs in time-reversal invariant spinless systems, which host butterfly-like nodal-lines (NLs) consisting of a pair of identical concentric intersecting coplanar ellipses (CICE). In this Communication, we unveil the intrinsic link between this exotic class of nodal-line semimetals (NLSMs) and a $${{\mathbb{Z}}}_{4}$$ Z 4 = 2 topological crystalline insulator (TCI), by including substantial SOC. We demonstrate that in three space groups (i.e., Pbam (No.55), P4/mbm (No.127), and P42/mbc (No.135)), the TCI supports a fourfold Dirac fermion on the (001) surface protected by two glide symmetries, which originates from the intertwined drumhead surface states of the CICE NLs. The higher order topology is further demonstrated by the emergence of one-dimensional helical hinge states, indicating the discovery of a higher order topological insulator protected by a glide symmetry.

scholarly journals An improved holographic nodal line semimetal

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Yan Liu ◽  
Xin-Meng Wu
Keyword(s):  
Mass Term ◽  
Nodal Line ◽  
Duality Relation ◽  
Strongly Coupled ◽  
Nodal Lines ◽  
Form Field ◽  
Improved Model ◽  
Fermionic Spectrum ◽  
Chern Simons ◽  
Tensor Operators

Abstract We study an improved holographic model for the strongly coupled nodal line semimetal which satisfies the duality relation between the rank two tensor operators $$ \overline{\psi}{\gamma}^{\mu v}\psi $$ ψ ¯ γ μv ψ and $$ \overline{\psi}{\gamma}^{\mu v}{\gamma}^5\psi $$ ψ ¯ γ μv γ 5 ψ . We introduce a Chern-Simons term and a mass term in the bulk for a complex two form field which is dual to the above tensor operators and the duality relation is automatically satisfied from holography. We find that there exists a quantum phase transition from a topological nodal line semimetal phase to a trivial phase. In the topological phase, there exist multiple nodal lines in the fermionic spectrum which are topologically nontrivial. The bulk geometries are different from the previous model without the duality constraint, while the resulting properties are qualitatively similar to those in that model. This improved model provides a more natural ground to analyze transports or other properties of strongly coupled nodal line semimetals.

scholarly journals Symmetry-protected nodal points and nodal lines in magnetic materials

2021 ◽  
Vol 103 (24) ◽  
Author(s):  
Jian Yang ◽  
Chen Fang ◽  
Zheng-Xin Liu
Keyword(s):  
Magnetic Materials ◽  
Nodal Lines ◽  
Nodal Points ◽  
Symmetry Protected

Effect of Dynamic Shear Force on Fastener Loosening in Assemblies

1997 ◽  
Author(s):  
Yubo Dong ◽  
Daniel P. Hess
Keyword(s):  
Cantilever Beam ◽  
Static Load ◽  
Nodal Line ◽  
Shear Stresses ◽  
Dynamic Shear ◽  
Bernoulli Beam ◽  
Cyclic Shear ◽  
Nodal Lines ◽  
Inertial Loading ◽  
Euler Bernoulli Beam

Abstract Placement and orientation of fasteners in assemblies is generally based on convenience or static load and strength considerations. Vibration and other dynamic loads can result in loosening of threaded product, particularly when cyclic shear stresses are present. This paper investigates the placement of a bolt and nut on a compound cantilever beam subjected to dynamic inertial loading. Calculations for an inertial loaded, cantilever, Euler-Bernoulli beam show that the dynamic shear stress is maximum near the dynamic nodal lines, and essentially vanishes near the anti-nodes. Experiments with a compound cantilever beam assembly with one fastener reveal that loosening occurs more readily when the bolt and nut are placed near a nodal line. Data presented include time to loosen, break-away torque, and acceleration level. The data shows that fastener integrity is maintained for longer periods of time and with lower tightening torques, when the bolt and nut are positioned away from nodal lines where shear stresses are lower, even though acceleration levels are higher.

scholarly journals Dirac nodal surfaces and nodal lines in ZrSiS

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6459 ◽  
Author(s):  
B.-B. Fu ◽  
C.-J. Yi ◽  
T.-T. Zhang ◽  
M. Caputo ◽  
J.-Z. Ma ◽  
...  
Keyword(s):  
Photoemission Spectroscopy ◽  
Dirac Fermions ◽  
Fermi Surfaces ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Nodal Lines ◽  
Nodal Points ◽  
Different Dimensions ◽  
Topological Semimetals ◽  
Symmetry Protected ◽  
Nodal Surfaces

Topological semimetals are characterized by symmetry-protected band crossings, which can be preserved in different dimensions in momentum space, forming zero-dimensional nodal points, one-dimensional nodal lines, or even two-dimensional nodal surfaces. Materials harboring nodal points and nodal lines have been experimentally verified, whereas experimental evidence of nodal surfaces is still lacking. Here, using angle-resolved photoemission spectroscopy (ARPES), we reveal the coexistence of Dirac nodal surfaces and nodal lines in the bulk electronic structures of ZrSiS. As compared with previous ARPES studies on ZrSiS, we obtained pure bulk states, which enable us to extract unambiguously intrinsic information of the bulk nodal surfaces and nodal lines. Our results show that the nodal lines are the only feature near the Fermi level and constitute the whole Fermi surfaces. We not only prove that the low-energy quasiparticles in ZrSiS are contributed entirely by Dirac fermions but also experimentally realize the nodal surface in topological semimetals.

scholarly journals Engineering Topological Nodal Line Semimetals in Rashba Spin-Orbit Coupled Atomic Chains

2019 ◽  
Vol 4 (1) ◽  
pp. 25 ◽  
Author(s):  
Paola Gentile ◽  
Vittorio Benvenuto ◽  
Carmine Ortix ◽  
Canio Noce ◽  
Mario Cuoco
Keyword(s):  
Three Dimensional ◽  
Nodal Line ◽  
Spin Orbit Coupling ◽  
Spin Orbit ◽  
Atomic Chain ◽  
Nodal Lines ◽  
Rashba Spin ◽  
Charge Potential ◽  
Atomic Chains ◽  
Two Phases

In this paper, we study an atomic chain in the presence of modulated charge potential and modulated Rashba spin-orbit coupling (RSOC) of equal periods. We show that for commensurate periodicities, λ = 4 n with integer n, the three-dimensional synthetic space obtained by sliding the two phases of the charge potential and RSOC features a topological nodal-line semimetal protected by an anti-unitary particle-hole symmetry. The location and shape of the nodal lines strongly depend on the relative amplitude between the charge potential and RSOC.

scholarly journals Insight into the Topological Nodal Line Metal YB2 with Large Linear Energy Range: A First-Principles Study

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3841
Author(s):  
Yang Li ◽  
Jihong Xia ◽  
Rabah Khenata ◽  
Minquan Kuang
Keyword(s):  
Energy Range ◽  
First Principles ◽  
Phonon Dispersion ◽  
Nodal Line ◽  
Spin Orbit Coupling ◽  
Metallic Material ◽  
Nodal Lines ◽  
Band Crossing ◽  
Crossing Point ◽  
Insight Into

The presence of one-dimensional (1D) nodal lines, which are formed by band crossing points along a line in the momentum space of materials, is accompanied by several interesting features. However, in order to facilitate experimental detection of the band crossing point signatures, the materials must possess a large linear energy range around the band crossing points. In this work, we focused on a topological metal, YB2, with phase stability and a P6/mmm space group, and studied the phonon dispersion, electronic structure, and topological nodal line signatures via first principles. The computed results show that YB2 is a metallic material with one pair of closed nodal lines in the kz = 0 plane. Importantly, around the band crossing points, a large linear energy range in excess of 2 eV was observed, which was rarely reported in previous reports that focus on linear-crossing materials. Furthermore, YB2 has the following advantages: (1) An absence of a virtual frequency for phonon dispersion, (2) an obvious nontrivial surface state around the band crossing point, and (3) small spin–orbit coupling-induced gaps for the band crossing points.

scholarly journals Multiple Dirac nodes and symmetry protected Dirac nodal line in orthorhombic α -RhSi

2020 ◽  
Vol 102 (11) ◽  
Author(s):  
Shirin Mozaffari ◽  
Niraj Aryal ◽  
Rico Schönemann ◽  
Kuan-Wen Chen ◽  
Wenkai Zheng ◽  
...  
Keyword(s):  
Nodal Line ◽  
Symmetry Protected

Coexistence of open and closed type nodal line topological semimetals in two dimensional B2C

2018 ◽  
Vol 6 (5) ◽  
pp. 1206-1214 ◽  
Author(s):  
P. Zhou ◽  
Z. S. Ma ◽  
L. Z. Sun
Keyword(s):  
Nodal Line ◽  
Two Dimensional ◽  
Nodal Lines ◽  
Closed Type ◽  
Topological Semimetal ◽  
Topological Semimetals

The detection of open and closed type nodal lines in the bilayer topological semimetal B2C on the substrate of Cu(110).

A nonsymmorphic-symmetry-protected hourglass Weyl node, hybrid Weyl node, nodal surface, and Dirac nodal line in Pd4X (X = S, Se) compounds

2020 ◽  
Vol 22 (39) ◽  
pp. 22399-22407
Author(s):  
Weizhen Meng ◽  
Ying Liu ◽  
Xiaoming Zhang ◽  
Xuefang Dai ◽  
Guodong Liu
Keyword(s):  
Nodal Line ◽  
Nodal Surface ◽  
Topological Semimetals ◽  
Symmetry Protected

Nonsymmorphic symmetry has been proved to protect band crossings in topological semimetals/metals.

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