Chirality flip of Weyl nodes and its manifestation in strained MoTe${}_2$

Abstract

Due to their topological charge, or chirality, the Weyl cones present in topological semimetals are considered robust against arbitrary perturbations. One well-understood exception to this robustness is the pairwise creation or annihilation of Weyl cones, which involves the overlap of two oppositely charged nodes in energy and momentum. Here we show that their topological charge can in fact change sign, in a process that involves the merging of not two, but three Weyl nodes. This is facilitated by the presence of rotation and time-reversal symmetries, which constrain the relative positions of Weyl cones in momentum space. We analyze the chirality flip process, showing that transport properties distinguish it from the conventional, double Weyl merging. Moreover, we predict that the chirality flip occurs in MoTe${}_2$, where experimentally accessible strain leads to the merging of three Weyl cones close to the Fermi level. Our work sets the stage to further investigate and observe such chirality flipping processes in different topological materials.

References in corpus (11)

• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Topological nodal line semimetals
• Weyl semimetals from noncentrosymmetric topological insulators
• Topological Euler class as a dynamical observable in optical lattices
• Observation of non-Abelian topological semimetals and their phase transitions
• Geometric approach to fragile topology beyond symmetry indicators
• Single fermion manipulation via superconducting phase differences in multiterminal Josephson junctions
• Topological correspondence between magnetic space group representations
• Elastic and electronic tuning of magnetoresistance in MoTe${}_2$
• Rare regions and avoided quantum criticality in disordered Weyl semimetals and superconductors
• Sixfold fermion near the Fermi level in cubic PtBi2

Cited by in corpus (14)

• Multi-gap topology and non-Abelian braiding of phonons from first principles
• Manipulation and braiding of Weyl nodes using symmetry-constrained phase transitions
• Topological continuum charges of acoustic phonons in 2D
• Phase transitions of non-Abelian charged nodal links in a spring-mass system
• Three-dimensional $\mathcal{P}\mathcal{T}$-symmetric topological phases with Pontryagin index
• Anomalous geometric transport signatures of topological Euler class
• Andreev reflection in Euler materials
• Second Euler number in four dimensional synthetic matter
• Stability of Weyl node merging processes under symmetry constraints
• Anomalous multi-gap topological phases in periodically driven quantum rotors
• Symmetry-adapted models for multifold fermions with spin-orbit coupling
• Gapped spinful phases obtained via Gutzwiller projections of Euler states
• Three-dimensional spinless Euler insulators with rotational symmetry
• Ferroelectrically Controlled Chirality Switching of Weyl Quasiparticles