Quasiparticle lifetime and edge localized states of graphite studied by high-resolution ARPES

We have performed an ultrahigh-resolution angle-resolved photoemission spectroscopy (ARPES) of high-quality graphite single crystal (kish graphite) to elucidate the band structure and many-body interaction. We clearly observed an extremely small hole-like Fermi surface centered at the K(H) point, a sharp quasiparticle peak in the vicinity of the Fermi level ($E_{F})$, and a kink in the dispersin at 0.18 eV.$^{1}$ We also found first evidence for the edge localized states near $E_{F}$, whose energy dispersion is markedly different from that of the bulk band. We will discuss the energy- and temperature-dependence of quasiparticle lifetime in relation to the strong electron-phonon coupling, the electron-plasmon interaction, and the electron-hole pair excitations. $^{1}$K. Sugawara\textit{ et. al., }Phys. Rev. Lett. \textbf{98} (2007) 036801. $^{2}$K. Sugawara \textit{et. al.,} Phys. Rev. B \textbf{73} (2006) 045124.