Phonon topology and winding of spectral weight in graphite

Abstract

The topology of electronic and phonon band structures of graphene is well studied and known to exhibit a Dirac cone at the K point of the Brillouin zone. Here, we applied inelastic x-ray scattering (IXS) along with $\text{ab initio}$ calculations to investigate phonon topology in graphite, the 3D analogue of graphene. We identified a pair of modes that form a very weakly gapped linear anticrossing at the K point that can be essentially viewed as a Dirac cone approximant. The IXS intensity in the vicinity of the quasi-Dirac point reveals a harmonic modulation of the phonon spectral weight above and below the Dirac energy, which was previously proposed as an experimental fingerprint of the nontrivial topology. We illustrate how the topological winding of IXS intensity can be understood in terms of atomic displacements, and highlight that the intensity winding is not in fact sensitive in telling quasi- and true Dirac points apart.

References in corpus (19)

• Berry Phase Effects on Electronic Properties
• Colloquium: Topological Band Theory
• Topological Acoustics
• Physics of three dimensional bosonic topological insulators: Surface Deconfined Criticality and Quantized Magnetoelectric Effect
• The phonon dispersion of graphite by inelastic x-ray scattering
• Topological acoustics
• Topological Sound
• Topological spin excitations in honeycomb ferromagnet CrI${}_3$
• Observation of Double Weyl Phonons in Parity-Breaking FeSi
• Computation and data driven discovery of topological phononic materials
• Dirac magnons in a honeycomb lattice quantum XY magnet CoTiO3
• Phonon surface mapping of graphite: disentangling quasi--degenerate phonon dispersions
• Order-by-Disorder from Bond-Dependent Exchange and Intensity Signature of Nodal Quasiparticles in a Honeycomb Cobaltate
• Topological Singularity Induced Chiral Kohn Anomaly in a Weyl Semimetal
• Topological gimbal phonons in T-carbon
• Thermal Evolution of Dirac Magnons in the Honeycomb Ferromagnet CrBr${}_3$
• Dirac magnons, nodal lines, and nodal plane in elemental gadolinium
• Magnonic Weyl states in Cu2OSeO3
• Chern numbers of topological phonon band crossing determined with inelastic neutron scattering