A single nodal loop of accidental degeneracies in minimal symmetry: triclinic CaAs${}_3$

Abstract

The existence of closed loops of degeneracies in crystals has been intimately connected to associated crystal symmetries, raising the question: what is the minimum symmetry required for topological character, and can one find an example? Triclinic CaAs${}_3$, in space group $P\bar{1}$ with only a center of inversion, has been found to display, without need for tuning, a nodal loop of accidental degeneracies with topological character, centered on one face of the Brillouin zone that is otherwise fully gapped. The small loop is very flat in energy, yet is cut four times by the Fermi energy, a condition that results in an intricate repeated touching of inversion related pairs of Fermi surfaces at Weyl points. Spin-orbit coupling lifts the fourfold degeneracy along the loop, leaving trivial Kramers pairs. With its single nodal loop that emerges without protection from any point group symmetry, CaAs${}_3$ represents the primal "hydrogen atom" of nodal loop systems.

References in corpus (6)

• Weyl semimetal phase in non-centrosymmetric transition metal monophosphides
• Surface States of the Topological Insulator Bi_{1-x}Sb_x
• Line of Dirac Nodes in Hyper-Honeycomb Lattices
• Topological Nodal Line Semimetals in CaP3 family of materials
• Tunable Line Node Semimetals
• New class of 3D topological insulator in double perovskite

Cited by in corpus (24)

• Topological carbon materials: a new perspective
• Hopf-link multi-Weyl-loop topological semimetals
• Semilocal exchange-correlation potentials for solid-state calculations: Current status and future directions
• Photoemission Spectroscopic Evidence for the Dirac Nodal Line in Monoclinic Semimetal SrAs${}_3$
• Evidence for a Dirac nodal-line semimetal in SrAs${}_3$
• Coexistence of Tunable Weyl Points and Topological Nodal Lines in Ternary Transition-Metal Telluride TaIrTe4
• Observation of topological nodal-loop state in RAs3 (R = Ca, Sr)
• Topological and trivial magnetic oscillations in nodal loop semimetals
• Mirror Protected Multiple Nodal Line Semimetals and Material Realization
• Two-dimensional type-II Dirac fermions in a LaAlO3/LaNiO3/LaAlO3 quantum well
• Enhanced thermoelectric performance by van Hove singularities in the density of states of type-II nodal-line semimetals
• Magnetic Field Induced Weyl Semimetal from Wannier-Function-based Tight-Binding Model
• Effective Hamiltonian of Topological Nodal Line Semimetal in Single-Component Molecular Conductor [Pd(dddt)${}_2$] from First-Principles
• Nodal line semimetal states in positive electrode material of lead-acid battery: Lead dioxide family and its derivatives
• Field-induced Metal-Insulator Transition in $\beta$-EuP${}_3$
• Role of Velocity Field and Principal Axis of Tilted Dirac Cones in Effective Hamlitonan of Non-Coplanar Nodal Loop
• Impurity-induced resonant states in topological nodal-line semimetals
• Spin and charge transport in topological nodal-line semimetals
• Optical transitions of a single nodal ring in SrAs${}_3$: radially and axially resolved characterization
• Existence of nodal-arc and its evolution into Weyl-nodes in the presence of spin-orbit coupling in TaAs & TaP
• Observation of quantum oscillations near the Mott-Ioffe-Regel limit in CaAs3
• Increasing the number of topological nodal lines in semimetals via uniaxial pressure
• Finite size and volume effects in line node semimetals: a first-principles investigation
• Pressure-induced superconductivity and topological phase transitions in the topological nodal-line semimetal SrAs3