Abstract
Using the standard tight binding model of 2D graphite with short range electron repulsion, we predict a gapless spin-1, neutral collective mode branch below the particle-hole continuum with energy vanishing linearly with momenta at the and points in the Brillouin zone. This spin-1 mode has a wide energy dispersion, to , and is not Landau damped. The “Dirac cone spectrum” of electrons at the chemical potential of graphite generates our collective mode, so we call this “spin-1 zero sound” of the “Dirac sea.” Epithermal neutron scattering experiments and spin polarized electron energy loss spectroscopy can be used to confirm and study our collective mode.
- Received 1 October 2001
DOI:https://doi.org/10.1103/PhysRevLett.89.016402
©2002 American Physical Society