Wavefront-dislocation evolution via quadratic band touching annihilation
Phys. Rev. B 114, 185124 – Published 21 September, 2026
DOI: https://doi.org/10.1103/svjh-t2xc
Abstract
Wavefront dislocations (WDs)—phase singularities observed in quasiparticle interference experiments—have been studied as real-space signatures of Berry phases in graphene-family systems. However, it has remained ambiguous whether WDs reflect the topological charge of the underlying band touchings or the pseudospin phase winding of the wave function itself. Here, we disentangle the roles of topological charge and phase winding of pseudospin texture in WD experiments by investigating various ways of the annihilation of quadratic band touchings in bilayer graphene and magneto-spin-orbit graphene systems. We demonstrate that WD evolution reflects the changes in the underlying pseudospin winding while remaining insensitive to the topological charge of the band touching itself. Our results provide a refined interpretation of WD experiments and present a solid-state proposal for engineering and observing WD evolution.
