title: Gapless spin-1 neutral collective mode branch for graphite.
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 Gamma and K points in the Brillouin zone. This spin-1 mode has a wide energy dispersion, 0 to approximately 2 eV, 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.
authors.affiliation: Institute of Mathematical Sciences, Madras 600 113, India.
authors.forename: G
authors.initials: G
authors.lastname: Baskaran
authors.forename: S A
authors.initials: SA
authors.lastname: Jafari