Various Nodal Lines in P63/mmc-type TiTe Topological Metal and its (001) Surface State

Searching for existing topological materials is a hot topic in quantum and computational chemistry. This study uncovers P63/mmc type TiTe compound—an existing material—is a newly discovered topological metal that hosts the various type of nodal line states. Different nodal line states normally exhibit different properties; they may have their individual applications. We report that TiTe hosts I, II, and hybrid type nodal line (NL) states at its ground state without chemical doping and strain engineering effects. Specifically, two type I NLs, two hybrid-type NLs, and one Γ—centered type II NL can be found in the kz = 0 plane. Moreover, the spin-orbit coupling induced gaps for these NLs are very small and within acceptable limits. The surface states of the TiTe (001) plane were determined to provide strong evidence for the appearance of the three types of NLs in TiTe. We also provide a reference for the data of the dynamic and mechanical properties of TiTe. We expect that the proposed NL states in TiTe can be obtained in future experiments.

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Computational Simulation of the Electronic State Transition in the Ternary Hexagonal Compound BaAgBi

Frontiers in Chemistry ◽

10.3389/fchem.2021.796323 ◽

2021 ◽

Vol 9 ◽

Author(s):

Yu Chang ◽

Xin Wang ◽

Sanggyun Na ◽

Weiwei Zhang

Keyword(s):

Theoretical Calculations ◽

Computational Simulation ◽

Tight Binding ◽

Surface States ◽

Nodal Line ◽

Spin Orbit Coupling ◽

State Behavior ◽

Nodal Lines ◽

Topological Features ◽

Wide Energy

Topological properties in metals or semimetals have sparked tremendous scientific interest in quantum chemistry because of their exotic surface state behavior. The current research focus is still on discovering ideal topological metal material candidates. We propose a ternary compound with a hexagonal crystal structure, BaAgBi, which was discovered to exhibit two Weyl nodal ring states around the Fermi energy level without the spin–orbit coupling (SOC) effect using theoretical calculations. When the SOC effect is considered, the topological phases transform into two Dirac nodal line states, and their locations also shift from the Weyl nodal rings. The surface states of both the Weyl nodal ring and Dirac nodal lines were calculated on the (001) surface projection using a tight-binding Hamiltonian, and clear drumhead states were observed, with large spatial distribution areas and wide energy variation ranges. These topological features in BaAgBi can be very beneficial for experimental detection, inspiring further experimental investigation.

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Strain tuning of closed topological nodal lines and opposite pockets in quasi-two-dimensional α-phase FeSi2

Physical Chemistry Chemical Physics ◽

10.1039/d0cp02334e ◽

2020 ◽

Vol 22 (24) ◽

pp. 13650-13658 ◽

Cited By ~ 1

Author(s):

Xiaotian Wang ◽

Zhenxiang Cheng ◽

Gang Zhang ◽

Minquan Kuang ◽

Xiao-Lin Wang ◽

...

Keyword(s):

Mechanical Strain ◽

Nodal Line ◽

Type I ◽

Type Ii ◽

Two Dimensional ◽

Nodal Lines ◽

Hybrid Type ◽

Α Phase ◽

Single Material

α-FeSi2 is a valuable candidate for spintronics application by utilization of type I, type II, and hybrid-type topological nodal line semimetals in a single material tuned by mechanical strain.

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

Condensed Matter ◽

10.3390/condmat4010025 ◽

2019 ◽

Vol 4 (1) ◽

pp. 25 ◽

Cited By ~ 1

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.

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

Materials ◽

10.3390/ma13173841 ◽

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.

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Spin–Orbit-Coupling-Induced Type-I/type-II Dirac Nodal-Line Metal in Nonsymmorphic CaSb2

Journal of the Physical Society of Japan ◽

10.7566/jpsj.88.044711 ◽

2019 ◽

Vol 88 (4) ◽

pp. 044711 ◽

Cited By ~ 1

Author(s):

Kohei Funada ◽

Ai Yamakage ◽

Naoya Yamashina ◽

Hiroshi Kageyama

Keyword(s):

Nodal Line ◽

Orbit Coupling ◽

Type I ◽

Spin Orbit Coupling ◽

Type Ii ◽

Spin Orbit

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Cubic ScPd topological metal: Closed nodal line, spin-orbit coupling-induced triply degenerate nodal point–Dirac nodal point transition

Results in Physics ◽

10.1016/j.rinp.2020.103553 ◽

2020 ◽

Vol 19 ◽

pp. 103553

Author(s):

Yang Li ◽

Dong Zhang ◽

Jihong Xia ◽

Rabah Khenata ◽

Minquan Kuang

Keyword(s):

Nodal Point ◽

Nodal Line ◽

Orbit Coupling ◽

Spin Orbit Coupling ◽

Spin Orbit ◽

Topological Metal

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Kramers nodal line metals

Nature Communications ◽

10.1038/s41467-021-22903-9 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Ying-Ming Xie ◽

Xue-Jian Gao ◽

Xiao Yan Xu ◽

Cheng-Ping Zhang ◽

Jin-Xin Hu ◽

...

Keyword(s):

Time Reversal ◽

Nodal Line ◽

Spin Orbit Coupling ◽

Fermi Surfaces ◽

Nodal Lines ◽

New Class ◽

Topological Materials ◽

Weyl Semimetals ◽

Chiral Crystals ◽

Torus Type

AbstractRecently, it was pointed out that all chiral crystals with spin-orbit coupling (SOC) can be Kramers Weyl semimetals (KWSs) which possess Weyl points pinned at time-reversal invariant momenta. In this work, we show that all achiral non-centrosymmetric materials with SOC can be a new class of topological materials, which we term Kramers nodal line metals (KNLMs). In KNLMs, there are doubly degenerate lines, which we call Kramers nodal lines (KNLs), connecting time-reversal invariant momenta. The KNLs create two types of Fermi surfaces, namely, the spindle torus type and the octdong type. Interestingly, all the electrons on octdong Fermi surfaces are described by two-dimensional massless Dirac Hamiltonians. These materials support quantized optical conductance in thin films. We further show that KNLMs can be regarded as parent states of KWSs. Therefore, we conclude that all non-centrosymmetric metals with SOC are topological, as they can be either KWSs or KNLMs.

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

npj Computational Materials ◽

10.1038/s41524-021-00672-9 ◽

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.

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Topological semimetal in honeycomb lattice LnSI

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1713261114 ◽

2017 ◽

Vol 114 (40) ◽

pp. 10596-10600 ◽

Cited By ~ 13

Author(s):

Simin Nie ◽

Gang Xu ◽

Fritz B. Prinz ◽

Shou-cheng Zhang

Keyword(s):

Condensed Matter ◽

Surface States ◽

Nodal Line ◽

Honeycomb Lattice ◽

Nodal Lines ◽

Weyl Semimetal ◽

The Standard Model ◽

Weyl Semimetals ◽

Topological Semimetals ◽

The Right

Recognized as elementary particles in the standard model, Weyl fermions in condensed matter have received growing attention. However, most of the previously reported Weyl semimetals exhibit rather complicated electronic structures that, in turn, may have raised questions regarding the underlying physics. Here, we report promising topological phases that can be realized in specific honeycomb lattices, including ideal Weyl semimetal structures, 3D strong topological insulators, and nodal-line semimetal configurations. In particular, we highlight a semimetal featuring both Weyl nodes and nodal lines. Guided by this model, we showed that GdSI, the long-perceived ideal Weyl semimetal, has two pairs of Weyl nodes residing at the Fermi level and that LuSI (YSI) is a 3D strong topological insulator with the right-handed helical surface states. Our work provides a mechanism to study topological semimetals and proposes a platform for exploring the physics of Weyl semimetals as well as related device designs.

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